october 22, 2018

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L O S A N G E L E S • S A N F R A N C I S C O • I R V I N E

October 22, 2018 Mrs. Cheryl Burwell Engineering and Technical Codes Manager City of Seattle Department of Construction and Inspections P.O. Box 34019 Seattle, WA 98124 Re: Lateral Peer Review of 9th & John Tower 820 John Street, Seattle WA Review Completion (17184.00) Dear Cheryl:

Nabih Youssef Associates (NYA) and Marshall Lew (AMEC Foster Wheeler) have been engaged to provide an independent structural design review of the structural design of the lateral force-resisting system for the new residential tower located at 820 John Street in Seattle, WA. This letter is to provide our opinion on the complete lateral system structural design, including both the foundation and the superstructure.

Project Summary

The overall 9th & John project consists of an approximately 295’ tall residential tower over 5 stories of basement parking. The typical floorplates of the tower are roughly square in shape with angled slab edges, with an expanded podium floorplate at Level 4 and below. The tower, due to its height and lateral system type, utilizes a non-prescriptive performance-based design (PBD) approach and is therefore the subject of this peer review.

Typical tower construction consists of 8.5” thick post-tensioned concrete slabs supported by concrete columns and an interior reinforced concrete shear wall core, which also comprises the lateral force resisting system. Below grade, slabs are 10” reinforced concrete, and a complete perimeter concrete basement wall is provided.

The project-specific design criteria provides lateral performance equivalent to that required by the use of the Seattle Building Code (SBC). The EOR establishes this through the use of a two-tier design including an elastic service-level analysis along with a nonlinear dynamic analysis at the MCE-R shaking level. A design-basis-earthquake (DBE) analysis, consistent with current prescriptive SBC requirements with approved exemptions, was also performed. A primary reference used for the MCE-R level analyses was the PEER Tall Buildings Initiative (TBI 2017) document. Project-specific design-level exemptions to the code include:

• The building height (295’) exceeds the maximum permitted by Seattle Building Code and ASCE 7-10 for reinforced concrete bearing wall systems

• The redundancy factor ρ will be set equal to unity for the design-level analysis

• Specifically related to the use of a condition mean spectrum (CMS) approach to the development of ground motions, the most current methodology for selection and modification of ground motions per ASCE 7-16 are referenced

• The response modification coefficient has been assigned R=6 for a bearing wall system



• Overstrength factor per ASCE 7 Table 12.2-1 was not used, and instead demands at the MCE level seismic event determined from the nonlinear response history analysis were used to evaluate the strength of critical elements to which the overstrength factor would traditionally be applied.

Collected Information We have received and reviewed the following information:

Geotechnical: 1. Site Specfic MCEr and SLE Response Spectra (08/23/17) 2. CMS Proposed Conditioning Periods Memo (08/31/17) 3. Site Specific CMS Memo (10/11/17) 4. Dynamic Springs Memo (11/13/17, revised 11/20/17) 5. Ground Motions Memo (11/21/17) 6. Final Geotech Report (11/29/17) 7. Final Seismic Report (01/04/18, revised 01/22/18)

Structural Calculations:

1. Basis of Design (08/04/17; 08/28/17; 10/11/17; 02/22/18)

• Supplemental Exhibit 3 (08/28/17) 2. Calculations - DE/SLE Submittal (09/05/17)

• Supplemental Exhibits 6, 26, 29, 30, 31, 34, 35, 37, 38, 41, 44 (11/06/17)

• Supplemental Models and Exhibits 11, 19, 27, 41.1, 45 (11/22/17) 3. Calculations – MCE Nonlinear Response History Analysis (11/23/17; 12/11/17)

• Steel Link Beam Redesign Summary (01/25/18)

• Supplemental Exhibits 45.1, 46, 48, 53, 55, 57, 58, 63, 65, 67, 72, 79, 82, 84, 86, 90, 96, 100, 103, 109, 113, 114 (01/25/18)

• Addendum I Steel Coupling Beam Redesign (02/26/18)

• Supplemental Exhibits 19, 27.1, 31.1, 45.1, 46, 48, 52, 53, 55, 56, 57, 58, 61, 63, 65, 67, 71, 72, 79, 80, 82, 84, 86, 90, 91, 96, 100, 103, 109, 113, 114 (02/26/18)

• Supplemental Exhibits 45.2, 45.3, 46.1, 50, 53.1, 61.1, 65.1, 74, 80.1, 81, 84.1, 86.1, 88, 91.1, 96.1, 97, 103.1, 103.2, 109, 109.1, 111, 113.1, 116, 121, 122 (04/26/18)

• Supplemental Exhibits 45.4, 72.1, 84.2, 86.2, 91.2, 109.2, 113.2, 116.1 (06/09/18)

• Supplemental Models and Exhibits 45.5, 61.2, 74.1, 91.3, 109.3, 111.1, 113.3 (06/18/18)

• Supplemental Exhibits 61.3, 111.2, 113.4 (07/30/18)

• Supplemental Exhibits 61.4, 113.5 (08/31/18) Structural Drawings:

1. Kickoff Reference Drawings (05/23/17) 2. DE,SLE, and Wind Design Drawings (09/05/17) 3. Phase II Permit Set (12/21/17) 4. Steel Link Beam Update (02/26/18) 5. Updated Set (05/10/18) 6. Updated Select Sheets (06/09/18)



Recommendations Throughout this review, we prepared a log of comments which we recorded on a standard form. We submitted these to the EOR, who responded back with discussion and supplemental materials. The process also included multiple conference calls.

A copy of the most recent version of this comment log is attached for your reference. As indicated in the log, all 123 comments discussed during the review are resolved to the peer reviewer’s satisfaction.

On the basis of the above, the design will provide seismic performance results equivalent to those obtained by the use of conventional structural systems that as designed per prescriptive requirements of the SBC. In addition, lateral wind performance was also reviewed as part of confirmation of the lateral system.

The review is now complete, and this letter serves as the final summarizing document.

Please call us at 213.362.0707 if you have any questions.

Sincerely,

NABIH YOUSSEF & ASSOCIATES

Nabih Youssef, S.E. Principall

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9th & John - Structural Design Peer Review Comment Log9/19/2018

Reviewers: Engineer of Record:Nabih Youssef MKA

Documents Received:1) Basis of Design 08/07/17 supplemental to initial kickoff documents and drawings2) DBE/SLE Initial Submittal 09/05/17; Responses 11/6 & 11/223) Initial MCE Package 11/23/174) 1st MCE Submittal 12/11/175) 2nd MCE Submittal 01/25/186) MCE Resubmittal (considering steel coupling beams) 02/26/187) 3rd MCE Submittal 04/26/188) 4th MCE Submittal 06/09/189) 5th MCE Submittal 06/18/18

10) 6th MCE Submittal 07/30/1811) 7th MCE Submittal 08/31/18

# Topic& Reference

Date ofComment

Reviewer Comment Date ofResponse

Design Team Response RelatedExhibit

Date ofResolution

Resolution/Notes

Submittal: Basis of Design (08/07/17; 08/28/17)

1 Basis of Design(08/07/17)

GeotechnicalConsiderations -Bearing Pressure

08/18/17 It is noted that bearing values will be increased by up to 1/3 for wind or seismic loads. Whenevaluated at MCE, what bearing pressure will be used? Is there an "ultimate" bearing pressure thatwill be provided by the geotech?

08/23/17 The allowable bearing pressure with a 1/3 increase will be used for the MCE load combinations (initialestimates suggest this will be adequate). Once the MCE loads have been generated and the matproportioned, GeoEngineers will review the estimated mat deformation and bearing pressures andconfirm/adjust the modulus of subgrade reaction if necessary.

09/08/17 Comment Resolved


Code References 08/18/17 ACI 318-11 is referenced, please update to ACI 318-14 08/23/17 The reference has been updated; please see updated Basis of Design.



Concrete ExpectedStrength (Pg. 10)

08/18/17 Per PEER TBI Table 4-2, it is noted that the multiplier on f'c may be smaller than 1.3 for high-strengthconcrete when determining f'ce. The 1.3 assumption will either need to be justified, or it will need tobe shown that critical capacity checks do not push the concrete strength to this full limit.

08/23/17 We propose keeping the 1.3 factor on all concrete mixes based on previous experience in Seattle.Please see Exhibit 3 for a representative 10 ksi mix design and test summary for a recent Seattleproject. 56-day strengths average 14.16 ksi, which suggests 1.3 is appropriate.

Exhibit 3



Table 3.3(Reinforcement)

08/18/17 80ksi rebar is shown for mat flexural, diaphragm chord and drag bars. Per ACI 318-14, resistance offlexure, axial, and shear within a special seismic system shall be limited to fy=60ksi.

08/23/17 We interpret the 60 ksi provision in section 20.2.2.5 as applying only to "...special moment frames,special structural walls, and all components of special structural walls…" and not to mat longitudinalreinforcement or diaphragm chord and drag bars. Additionally, the mat and diaphragm chord and dragbars are force-controlled actions and not expected to experience non-linearity.



Cladding Loads 08/18/17 Stone is noted as one of the cladding materials? Is this very prevalent throughout the cladding? If so,please provide a breakdown of the locations, how the weight is determined, and how it is applied inthe analysis models.

08/23/17 Stone occurs only at the podium, Levels 1 - 4. The load maps (which will be submitted with the DEpackage) show where these loads occur. Cladding loads are applied as line loads to beam elements inthe analysis models. 09/08/17 Comment Resolved


Ground Motions (Pg.15)

08/18/17 Confirm that per PEER TBI Section 3.3, a sufficient number of CMS will be created in order to provide90% participating mass in each horizontal direction of the structure.

08/23/17 This is confirmed per the memo from GeoEngineers dated July 12, 2017 and title "9th and JohnApartments - Site-Specific Ground Motion Procedures" . See p. 7 under "Ground Motion Selection andModification" for details.

09/08/17 Our understanding is that Pg. 7 of the noted report refers to 90% mass participation as a guideline interms of the range of scaling, not in terms of a target period for CMS creation. A GeoEngineers emailfrom 08/31 stated "We plan to condition the short-period CMS to the average of the 2nd mode periods(0.6sec) and the long period CMS to longest first mode (3.1sec). The long-period CMS will be adjustedto be equal to the MCEr spectrum across the first two modes, as recommended in Section 3.3 in PEERTBI 2017, and up to T=3.5seconds to account for some expected nonlinearity". Some relatedcomments:

1) The spreadsheet that was attached to this email showed that the 2nd mode periods only accountfor about 60% of the cumulative mass participation, instead of 90%. Please clarify, or modify /addmatching periods to provide 90% participating mass in each direction of the structure (see attachedComment #6 Figure tab )

2) The target periods that are utilized appear to be coming from the SLE analysis (based upon the titlein the attached spreadsheet). Please note that a few of the currently open comments as of this dateinclude potential modifications to stiffness of the SLE model which could affect the model period. Allperiods and period ranges will need to be confirmed given the actual nonlinear model through whichthe motions that are scaled to the CMS spectra will be run (assuming that this nonlinear model is notalready created). Similarly, the expected period elongation noted as 1.2T for the CMS long-periodtarget, and 1.5T in relation to ground motion range of scaling will both need to be revisited andconfirmed as well.

3) For the long-period CMS, it appears as though the spectrum will match the MCEr spanning betweenthe X and Y 1st mode directions per PEER TBI Section 3.3. It is unclear why this approach is not alsoundertaken for the short-period target. Please clarify.

(Also refer to geotech comment #17)

10/16/17 1. Per email discussion, it was agreed that periods and mass participation would be derivedconsidering no mass at basement levels. Exhibit 6 provides new modes and mass participationswithout consideration of basement mass. The first three modes in the X-direction provide 92.5% massparticipation and the first three modes in the Y-direction provide 94.2%.

2. Please see responses to comments 11, 15, 18, and 35 for proposed modifications to the model. Thenew SLE periods are as shown in Exhibit 6. The values are little changed from the previous iteration.For comparison, the previous first and second overall modes were 3.11 and 2.38 versus the newperiods of 3.21 and 2.35.

3. A range will also be utilized for the short-period. See GeoEngineers Report titled "Site-SpecificConditional Mean Spectra" dated 10/11/2017. Note that the values in this report will be fine-tunedbased on the finalized SLE model and the pending MCE results.

Exhibit 6

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11/17/17 Previous comments are resolved, but on a related note regarding target periods for CMS:On 11/13/2017, a "Vertical Dynamic Mat Foundation Springs" Memo was received from GeoEngineers.This memo appears to indicate that soil flexibility (per soil springs) will be included in the nonlinearresponse history analysis. This appears to be a change to the BOD which stated that all models willinclude analytical nodes fixed at the top of the mat. Please confirm this change, and provide furtherstructurall narrative if so.In terms of CMS, inclusion of the soil springs will impact the periods of the nonlinear analysis model.Currently, target periods for the CMS are taken from the SLE model which to our understanding willnot include any soil springs. Please clarify how the flexibility introduced with the soil springs in thenonlinear response history analysis will be represented in the target periods chosen for the CMS.As noted in the comments above, the target periods are to be confirmed per the MCE analysis modelregardless of inclusion of soil springs.

11/20/17 The intent is not to introduce springs in the nonlinear model. The nonlinear model will follow the Basisof Design. The soil springs have been (and will be) used in the standalone SAFE models. GeoEngineershave updated their memo to reflect this. 11/30/17

CommentResolved


Ground Motions (Pg.15)

08/18/17 It is noted that the PEER TBI recommendation to provide a minimum of 5 records for sourcescontributing more than 20% to the hazard will not be fulfilled. Please clarify and justify.

08/23/17 Per email correspondence with GeoEngineers dated 4 August 2017: "At this time we do not plan tofulfill the recommendation that a minimum of 5 records be selected for sources that contribute >20%to the hazard. We plan to develop of suite of 11 records per ASCE 7-16 and select the records based onseismic hazard disaggregation. The 5 record minimum recommendation would result in a groundmotion suite that does not preserve the relative contribution of the various sources to the total hazardbased on the disaggregation, and as a result will yield results that may over- or understate theresponse from certain sources." Additionally, Geotechnical Comment #8 of this log accepts theproposed Ground Motion procedures approach.



Table 5.2 (Pg. 19) 08/18/17 1) It is noted that shear in basement walls is deemed a "critical" force controlled element. It isacceptable to maintain this criteria, or also to relax it to an "ordinary" force controlled action.2) Please provide discussion as to how it will be intended to evaluate the column axial, flexure, andshear (as noted in this table) as a critical force-controlled element. Will all columns be explicitlyincluded in the analysis models?3) Please include in-plane normal forces other than collectors (for typical diaphragms) within this list

08/23/17 1) Basement walls will be relaxed to ordinary force-controlled per Appendix E.2) Only column shear will be modeled as a force-controlled element. Combined axial and bending willbe treated as a deformation-controlled action and detailed appropriately per note 3 of TBI Table E-1.Detailing of slab-column joints is described in Section 5.3 of the Basis of Design.3) This item has been added to Table. 5.2



Table 5.2 (Pg. 19) 08/18/17 1) It is noted that shear in basement walls is deemed a "critical" force controlled element. It isacceptable to maintain this criteria, or also to relax it to an "ordinary" force controlled action.2) Please provide discussion as to how it will be intended to evaluate the column axial, flexure, andshear (as noted in this table) as a critical force-controlled element. Will all columns be explicitlyincluded in the analysis models?3) Please include in-plane normal forces other than collectors (for typical diaphragms) within this list

08/23/17 This is a repeat of Comment 8.



P-Delta Effects (Pg. 21) 08/18/17 Please justify P-delta loads based upon only the self-weight of the structure (in lieu of some overallgravity load combination). How will this be represented in the linear and nonlinear models?

08/23/17 P-delta load combinations should be as follows:- SLE and wind service: 1.0D + 0.5L, where L is as defined in Table 5.5.- DE and wind strength: 1.2D + f1L (ASCE-7)- Nonlinear model: 1.0D + 0.5L, where L is as defined in Table 5.7.Section 5.2 of the Basis of Design has been updated accordingly. 09/08/17 Comment Resolved


Table 5.3 Elastic ModelStiffness

08/18/17 Justify the use of 0.9EI for structural wall in-plane flexural stiffness at SLE in light of the PEER TBIrecommended value of 0.75.

Similarly, justify the use of 0.8EI at DE, given that this is stiffer than the PEER recommended value atSLE.

08/23/17 0.75EI will be used for both SLE and DE. Also note that the axial value has been changed to match theflexural; in ETABS, the modifier on wall axial and wall flexural is the same. The Basis of Design has beenupdated accordingly.

09/08/17 Please justify the use of the same stiffness modifier both at SLE and DBE. As noted in various sectionsof PEER TBI, the structure is expected to remain "essentially" elastic at SLE. It is not expected toremain "essentially" elastic at DBE - therefore justify the use of the same effective stiffness modifiers(instead of a lower value for DBE) for flexural stiffness of the walls in the linear models.

10/04/17 We propose using 0.70 for DE and maintaining 0.75 for SLE.

11/17/17 The proposed value of 0.7 for DE represents a 7% decrease in stiffness from SLE to DE. To justify use ofthis proposed value, please provide (only) interstory drift results for a parametric study model where a0.5 modifier is used at DE. Given acceptable drift results at DE given this parametric study, use of 0.7can be used for the actual design model.

11/20/17 Please see Exhibit 11 for a comparison of story drifts between DE models with 0.7 and 0.5 stiffnessmodifiers, respectively. As expected, drifts increase slightly, but are still well below the limit of 2%. Thebackup material from the original calculations w/ 0.7 is included in the exhibit.

Exhibit 11

11/30/17CommentResolved



08/18/17 Confirm/update that, in general, the shear modifiers this table are intended to utilize shear modulus"G" in lieu of elastic modulus "E", such that the majority of these entries read "1.0GA" instead of thecurrent "1.0EA"

08/23/17 The table has been updated to replace E with G for shear. In actuality, there is only a semanticdifference since Poisson's ratio is assumed to be constant with Gc = Ec/(2(1+v)).




08/18/17 Justify the flexural stiffness modifiers provided for the basement walls, as they currently match thestiffness modifiers provided for the core wall, at both DE and SLE.

08/23/17 The basement wall modifiers have been updated to match the TBI recommendation of 1.0 at SLE. ForDE, a value of 1.0 will also be used.




08/18/17 Justify the use of 0.2EI flexural modifier for coupling beams at DE. Given that the same equation isutilized at both SLE and MCE for coupling beam stiffness in Table 4-3 of PEER TBI, it would berecommended to use this same equation at DE as well. Specifically, although it would only seem tooccur at a few isolated beams within the tower, any beam with l/h>2.8 would see a greater stiffnessreduction at SLE than DE.

08/23/17 The equation for SLE will be applied to DE. Table 5.3 has been updated.




08/18/17 Non-transfer diaphragm stiffness is currently assigned a 0.01EI factor for flexural stiffness at SLE. Isthis intended to represent out-of-plane stiffness? If so, how will the outrigger action be evaluated atSLE?

08/23/17 This factor is intended to model outrigger behavior and should have been entered as 0.35EI. Table 5.3in the Basis of Design has been updated.

09/08/17 0.35EI would imply a reduction in stiffness of almost 70% of the slab in outrigger action at SLE. Thisstiffness reduction is typically the value seen at the MCE-level models. Please justify it's use at servicelevel events, or utilize a lesser reduction, given a response that is supposed to remain "essentially"elastic.

10/06/17 We propose using 0.5*EI for SLE, which aligns with TBI's recommended value for beam flexure for theSLE earthquake.




08/18/17 Mat in-plane shear stiffness at SLE is recommended as 0.8EA per PEER TBI Table 4-3, in lieu of the1.0EA shown in the current table.

08/23/17 This has been updated to match TBI.



MCE StiffnessAssumptions (Pg. 23)

08/18/17 The stiff and soft properties (25% and 10% respectively) proposed as significantly "softer" than thevalues proposed by ATC-72 App. A for backstay bounding analysis (50% and ~5-20%). Please justify.

08/23/17 The 25% UB stiffness assumption of the diaphragm at MCE loading has been accepted on multipleother PBD tower projects on the West Coast. Since concrete diaphragm stiffness testing data does notexist to our knowledge, engineering judgment is necessary in the bounding of this assumption. Testingof other concrete systems with low axial stresses (link beams and short shear walls), have shown arapid reduction of system stiffness after cracking to levels of 25% and less. It is MKA's opinion that the25% UB stiffness assumption, at the MCE load cases, allows for a reasonable design of the diaphragms,while ensuring the core wall system maintains its integrity to the foundations.

09/08/17

CommentResolved.Depending onresults oftransferdiaphragmanalysis, localparametricstudies may benecessary atlater stages ofdesign.


MCE StiffnessAssumptions (Table 5.4)

08/18/17 Please include stiffness criteria for coupling beams, basement walls, in-plane shear stiffness of the corewalls, and the mat (for use in SAFE model when evaluating the foundation).

08/25/17 These values have been added to the updated Basis of Design.

# Topic& Reference

Date ofComment



Date ofResolution

Resolution/Notes

3 of 19

09/08/17 1) Please confirm/update that the intent of basement wall shear was to be 0.5GcAg, not 0.2GcAg.

2) Similarly, please confirm/update that intent of shear stiffness for transfer diaphragms (in-plane)was 0.1EcAg and 0.2EcAg instead of 0.1GcAg and 0.2GcAg.

3) For transfer diaphragms out-of-plane flexural stiffness: The "**" footnote notes that out-of-planeflexural stiffness will be represented with beam elements. While this is understood for the typicalfloors that will not have the slab "shells" modeled, will this still be the case at the transfer diaphragmswhere the slabs will be modeled explicitly?

4) Similar to 3) above as well as Comment #15, please confirm the out-of-plane flexural stiffness of thenon-transfer diaphragms - 0.1EcIg seems very low, and it is understood that this will be representedwith effective beam elements.

5) Justify the use of 0.8GcAg for mat in-plane shear stiffness in lieu other typical 0.4EcAg (1.0GcAg)value

6) Given openings along a majority of the edge of the western core, please provide a description ofhow the outrigger slab will be represented along this face of the core

10/11/17 Please see the updated Basis of Design for the following:

1) Confirmed. The values have been changed to 0.5GcAg.

2) Gc is correct. It should be 0.1GcAg for the soft diaphragm and 0.25GcAg for the stiff diaphragm.

3) This was inadvertently reversed. The intent is to provide outrigger beams at elevated (non-transfer)levels and to provide negligible out-of-plane bending stiffness for transfer diaphragms (0.01EcIg).

4) Per comment 3) above, at non-transfer diaphragms, outrigger beams will be provided to model out-of-plane bending.

5) We will use 1.0GcAg (0.4EcAg).

6) The outrigger slabs will be modeled as beam elements off the corners of the core with parameterscommensurate with the width of slab engaged (this will be described in more detail in the forthcomingMCE package).



MCEr Evaluation (Pg.31)

08/18/17 As part of the global acceptance criteria, please include discussion within this section as to what will beconsidered the "valid range of modeling" as referenced by the second bullet point.

08/25/17 The valid range of modeling will be defined by hysteretic models based on test data (per TBI Section6.8.2). If the ultimate deformation capacity is exceeded for any given component, the strengthassociated with the mode of deformation for this component will be negligible for the remainder ofthe analysis.

CommentResolved,

pending furthersubmittals

09/08/17 As part of either the BOD, or a later submission with a narrative of nonlinear modeling, please providereference test information justifying the ultimate deformation capacities as noted in Table 5.9 forcoupling beam rotation, core wall reinforcement strain, and core wall concrete compression strain.

10/10/17 To be included in nonlinear package.

11/17/1711/22/172/22/18

Please see Exhibit 19 for references, including new diagrams for structural steel coupling beams andupdates based on Comments 52 and 54.

Exhibit 1911/17/17

CommentResolved


MCEr Evaluation (Table5.9)

08/18/17 Table 5.9 notes taking the average of 11 analyses and comparing this average value to acceptancecriteria (δu). PEER TBI Section 6.8.2, governing the acceptance criteria of deformation controlledactions, instead states that if δu is surpassed for any component during any record, either the analysisis deemed to have an unacceptable response, or the component strength associated with that mode ofdeformation should be negligible for the remainder of the analysis. Please provide additionaldiscussion in this section to coincide with PEER TBI 6.8.2 language. Also see comment #19 above.

08/25/17 The language in Table 5.9 has been changed to state "maximum of the eleven analyses" instead of"average." As stated in Comment #19, the acceptance criteria will be built into the hysteresis models.Language has been added to the Basis of Design. 11/17/17 Comment Resolved


MCEr Evaluation (Table5.9)

08/18/17 Please include proposed δu values for concrete compressive strain at lesser confinement amounts than"fully confined".

08/25/17 The axial compressive strain limits have been updated to the following:Full confinement: 0.005 ≤ εc ≤ 0.015Intermediate confinement: 0.003 ≤ εc < 0.005

09/08/17 Will a minimum of intermediate confinement be provided wherever concrete compressive strains arebeing monitored? Otherwise, please also provide ultimate deformation capacity for concrete strainwith less-then-intermediate confinement

09/18/17 No confinement will be provided where concrete compressive strains are less than 0.003.



MCEr Evaluation (LoadCombinations)

08/18/17 Table 5.7 provides a different MCEr load combination compared to those shown in Table 5.10 and 5.11-please clarify.

08/25/17 Table 5.7 is the basic load combination used in the PERFORM analysis (see TBI Section 6.5commentary). Tables 5.10 and 5.11 are load combinations for post-processing checks of force-controlled elements.



MCEr Evaluation (Force-Controlled Actions Pg.

32)

08/18/17 Please clarify what actions will be considered a force-controlled action that are limited by a well-defined yield mechanism. It is suggested that this criteria could be included in Table 5.2.

08/25/17 Two actions will be limited by a well-defined yield mechanism: conventional coupling beam shear andcolumn shear, which will be designed based on the force that can be delivered considering themaximum probable flexural strength, Mpr. This information has been added to Table 5.2.



MCEr Evaluation (Force-Controlled Actions Pg.

33)

08/18/17 Please provide additional discussion/criteria regarding the value "B" in use for force-controlled actionsthat are not limited by a well-defined yield mechanism. As noted in PEER TBI 6.8.3 Commentary, whileB=1.0 is recommended for structural steel elements, the material variability and conservatism in thepredictive strength formulation for reinforced concrete may be larger. If a larger value is intended tobe used, please provide the justification for these values.

08/25/17 For concrete components, larger values of B will be used based on expected material properties. f'cewill be substituted for f'c and fye for fy. At this time, it is not anticipated that B will be further adjustedfor any inherent conservatism in the predicite equations specified by the materials standards (asdiscussed in the TBI commentary to equations 6-3 and 6-4).


Submittal: DBE/SLE/Wind Package (09/05/17; 11/06/17; 02/26/18-SRC Updates)

25 DBE/SLE Submittal(09/05/17)

SLE Analysis Model 09/08/17 PEER TBI Section 5.4 notes to incorporate in the model all components and elements of the gravity-force resisting system that contribute significantly to lateral strength and stiffness. Has inclusion of thebeams at Level 1 and 4 been investigated to understand if, given fixity of the columns, their inclusionresults in any noticeable difference in behavior or force distribution at these floors?

10/30/17 The inclusion of the beam has a negligble effect on global building performance. They will be studiedat the diaphragm level and will be included in a forthcoming Exhibit (see the response to Comment 45)

11/17/17 Pending future exhibit as noted in response 02/22/18 Analysis of the diaphragms is shown in other Exhibits (45.1, 91, and 96). Two versions of the SLE modelwere run to investigate the effect of the Level 1 and Level 4 beams (note that beams at 26, 27, and 28have been modeled from the start). Periods were as follows:SLE (no beams): T1 = 3.16s, T2 = 2.34s, T3 = 2.01sSLE (beams): T1 = 3.14s, T2 = 2.33s, T3 = 2.00sMaximum story drifts were the same (0.11% and 0.09%).

Exhibits 45.1,91, 96



Progress Drawing Set 09/08/17 Please provide a quick calculation confirming that 50psf will cover all built-up slab conditions thatoccur, accounting for both concrete slab and stem walls.

10/11/17 Exhibit 26 contains a spreadsheet with calculations for all of the built-up slab areas. The loading variesdepending on curb height and area. The lateral models will be updated for the higher mass where itoccurs. The load will be applied as a smeared area load. For gravity loading, the loads are applied asarea loads for the slab and line loads for the supporting walls.

Exhibit 26



Progress Drawing Set 09/08/17 Per sheet S2.04, Lvl 4 has a set of beams along Gridline C that appear to fly by the columns at ~C/3 andC/4. Is this intentional?

09/18/17 Yes, this is intentional. The beams are acting as slab steps at the transition from the interior to exteriorjust north of the beam where the built-up slab does not occur. As such, the beam/steps need to belocated where shown. Additional reinforcement will be provided here to act as a corbel to add supportto the beam. This will be included in the superstructure permit drawings and calculations to besubmitted in mid-December.

11/17/17 Pending future drawings and calculations as noted in response 11/20/17 Please see Exhibit 27 for the corbel calculations. Exhibit 2711/30/17 While gravity-design corbel calc is acceptable, please ensure that representation of these steps are

included in the diaphragm design (which we understand to be forthcoming) to ensure adequatediaphragm load path.

02/22/18 The geometry of the slab has been revised to minimize the dipahragm forces through these corbels.Beams at Grids 3 and 4 have been added so that the collector reinforcement does not induce torsionon the Grid C step. There will be a small component of vertical force in the corbel due to warpingeffects as shear transfers parallel to and across the step. Please see Exhibit 27.1 for details. Thecalculation shows that the seismic load in combination with dead load is less than the factored gravityload, therefore the corbel design is adequate.

Exhibit 27


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Progress Drawing Set 09/08/17 Note #12 on S3.01 states that f'c=8ksi up through Lvl 9, and 6ksi above this. The provided analysismodel utilizes 8ksi for the entire core height. Please clarify.

10/04/17 The model has been updated to match the drawings - 6 ksi above Level 9. Results have been updated;present and future Exhibits and calc packages contain this update.

11/17/17 As part of forthcoming package, please include update ETABS model (and associated updated drawingsas well)

11/20/17 Please see the ETABS model and foundation permit drawings attached to this response. ETABS,Ph. I dwgs 11/30/17 Comment Resolved


Progress Drawing Set 09/08/17 Please provide a section directly above Lvl 1 on 17/S3.04 to show how the door opening will beincorporated.

Please also provide a description of the intended load path in this region where the boundary zoneabove will be discontinued due to this opening

11/03/17 Please see Exhibit 29 for the requested section and a calculation showing the load path and thereinforcement around the opening. Boundary zone elements at each side of the opening will extendone level above and below the opening. The concrete wall panels above and below the opening aredesigned a strut-and-tie elements for axial load. Wall shear above and below the opening is dragged tothe solid section of the wall as shown in the calcs. Note that these will calculations will be repeated forthe MCE case.

Exhibit 29

11/17/17 Response notes that boundary zone elements at each side of the opening will extend one level aboveand below the opening. On the sections provided in Exhibit 29, it is not clear that the boundary zoneextending 6' south of the opening continues to the story above and below, as it is titled "Level 1 toLevel 2". Is this intended to be titled "P1 to Level 3"?

Comment also to be revisited at MCE as noted in response

11/20/17 The section was subsequently updated for the foundation permit set (attached with this response) tostate that the noted boundary zone continues from P1 to L3 .

Ph. I dwgs



Progress Drawing Set &Calcs

09/08/17 Please provide the calculations related to the size and spacing of the provided boundary zoneconfinement reinforcement. Please confirm that, as shown on S3.11, the intent is to increase thevertical spacing of confinement bars below Level 4.

10/27/17 Please see Exhibit 30 for calculations. A change in spacing was not intended and has been fixed. Level 4should be 6" on center.

Exhibit 30



Progress Drawing Set &Calcs

09/08/17 For column step transitions, such as that shown in 20/S5.04, the extended-length column used as thetransition point will attract some degree of flexure in the model. Please provide calcs to show that theslab alone, as shown in this section, has adequate capacity to resist the potential overturning demandfrom this extended column.

(This action should be accounted for at SLE/DBE, and the future MCE analysis)

10/11/17 See Exhibit 31 for loading and calculation of resisting slab reinforcment. At column transitions, columnaxial loads (combined gravity and lateral) will be resisted by a slab couple (drag reinforcement) at thetop and bottom of the column transitions. For the DE model, columns are pinned so moments will notbe transferred to the slab. Please see Exhibit 31. A final design check will be performed with the MCEloads.

Exhibit 31

11/17/17 How is flexure of the column itself resisted at the slab/column interface? Are the columns pinned inthe SLE model?

11/20/17 Columns are modeled as fixed in the SLE model and internal moments are part of the column design.These will be addressed as part of the superstructure permit calcs.

11/17/17 As part of forthcoming superstructure calcs, ensure that the ability for the slab at extreme ends of thecolumn to resist the demands (including flexural demands) developed there are evaluated.

02/22/18 Please see Exhibit 31.1 for a calculation of slab joint capacity for the induced Mpr assumed in the slabmicro-outrigger approach.

Exhibit 31.1

03/20/18 It is not clear that the provided exhibit addresses the particular concern regarding how thetension/compression couple of flexure is resolved, particularly at the bottom of the column (please see"Comment #31" tab for clarification. Please confirm if this is addressed as part of Exhibit 31.1, orprovide supplemental information.

04/05/18 See p.2 of Exhibit 109 (previously submitted) for the load path through the knuckle columns. Theassumption is that loading is resolved through an inclined axial force in the column and a balancingcouple in the slab with the assumption that no moment is imposed at the base of the knuckle.

The gravity moments and shears generated at the slab interface are conservatively resisted by thecolumn cross-section below the slab (i.e., only the column below is modeled in Ram Concept, not theabove column).

Exhibit 109.Exhibit 111

05/18/18

Comment Resolved- See Comment#111


Calcs - Pg. 6 09/08/17 Boundary conditions are note as rotationally released - however the DBE/SLE models show rotationalfixity. Please clarify which is correct.

10/04/17 There is not intended to be rotational fixity at the base of the structure. Core wall and basement wallnodes were modeled with translation restraint (UX, UY, and UZ) only. Column nodes were modeledwith 6 degrees of freedom (UX, UY, UZ, RX, RY and RZ) with translations fixed and rotations released.This was done just for similarity with modeling of column end releases within the DE model forcolumns in stories above. So, effectively the columns were pinned. For clarity, we have revised themodel such that columns now have translation only restraint (UX, UY and UZ) with no moment releaseat the bottom of the columns at the base of the building. This is also effectively a pinned endcondition. This approach produces identical results and is numerically stable.



Calcs - Pg. 8 - Table 2.2 09/08/17 It may not affect a large amount of loading, but please confirm that while a 10psf partition "mass" isrepresented, the gravity load representation of partitions is considered a live load, not dead load.

09/18/17 Confirmed. The 10 psf is the minimum office partition mass per ASCE-7 Section 12.7.2.2 (EffectiveSeismic Weight). For bookkeeping purposes, the office partition load is 20 psf of the 30 psfsuperimposed dead load listed in Table 2.2. Per ASCE-7 4.3.2, office partitions shall be a minimum of15 psf. Multiplying by the ratio of load factors to convert from LL to DL: 15psf x 1.6/1.2 = 20psf.



Calcs - Pg. 19 09/08/17 Similar to the one shown for the typical floorplate, please provide figures locating where drift pointswere monitored for torsion at the other unique-shaped floorplates.

10/10/17 Please see Exhibit 34. Exhibit 34



DBE and SLE Model,and Calcs Pg. 22 and 31

09/08/17 (Also see comment #11)

Given the effective stiffness modifiers shown in Table 2.1, identical stiffness multiplier should beassigned to the shear walls and coupling beams in both the DBE and SLE model. While this itself is stillunder review, this would imply that the two models would have relatively similar periods. This doesnot appear to be the case when comparing the periods on Pg. 22 vs. Pg. 31.

It appears that this is likely due to the fact that instead of applying the effective coupling beamstiffness per equation in Table 2.1 (consistent for DBE and SLE), a flat 0.2EI is applied to the couplingbeams in the DBE model, while 0.3EI is applied to the coupling beams in the SLE model. Please updateper Table 2.1, and ensure to inform potential updates to the CMS target periods which appear to beobtained from the SLE model.

10/05/17 Both models should have coupling beams modeled as 0.07(l/h)*EI per comment #14. The couplingbeams have been updated per Table 2-1 (the result is only a select few with 0.21 instaed of 0.2). SeeExhibit 35 for coupling beam stiffness modifiers.

The difference in periods between DE and SLE is due to a number of items: - nominal properties (DE) vs. expected properties (SLE) - pinned columns (DE) vs. fixed columns (SLE) - pinned beams (DE) vs. fixed beams (SLE) - P-delta LC: 1.2D + f1L (DE) vs. 1.0D +0.5Lexp (SLE) - SLE - micro-outrigger effect adds small amount of overall stiffness

Exhibit 35


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Calcs Pg. 24 09/08/17 Please confirm Figure 3.5, which appears to indicate a very similar story shear distribution between theSLE and DBE analysis. Is there a similar issue with Figure 3.8?

10/16/17 These plots were re-checked and are correct.



Calcs Pg. 45 09/08/17 1) For diagonally reinforced beams, confirm that φVn was limited to φ10root(f'c)Acw [φ is not shown]

2) For the conventionally reinforced coupling beams:-For DBE, confirm that the design shear force is determined from ACI 318-14 18.6.5 (Ve from Mpr).Also, confirm what φ factors are used in flexure and shear.-For SLE, confirm that φ is considered when checking shear in these coupling beams, given theirdesignation as a force-controlled action

3) Please provide charts similar to those provided, with Vu for the coupling beams listed

11/03/17 1) Confirmed. Please see Exhibit 37, p. 3 for an updated p.45.

2a) Confirmed - see Exhibit 37, p. 4.2b) Phi = 0.9 for flexure and 0.75 for shear2c) Phi was considered.

3) See Exhibit 37 for tables of Vu values.

Exhibit 37



Calc Section 7 (WallFlexure)

09/08/17 While Table 7.2 and 7.3 show upwards of 80 combinations, the spColumn results indicate 16combinations. Please clarify. Please also clarify where the SLE combinations were evaluated.

10/30/17 The original design did include all combinations, but the report sample only showed SLE -- the 16 loadcombinations are the 8 SLE combinations x 2 for the top and bottom of wall. The DE and Windcombinations (164 total) are shown for a sample wall pier in Exhibit 38.

Exhibit 38



Calc Section 7 (WallFlexure)

09/08/17 Referencing Figure 7.2: Along the height of the building, were effective flange widths per ACI 318-14Sect. 18.10.5.2 utilized for the PMM sections? If not, please confirm the the approach of utilizingentire halves of the core is equal or conservative.

Also, please confirm that axial loads on the sections from seismic demands were included as part ofthe axial load applied to the analysis section. For example, it would be expected that the axial loadwould differ significantly between EQX being applied in the positive or negative direction (such asbetween LC 6 and 7 on Table 7.2), however there appears to be minimal difference in the axial demandother than for the different gravity load combinations.

10/30/17 The entire length of flange has been used in the core wall design. It is reasonable to utilize only part ofthe core flange as the effective flange width for relatively short buildings. However, for a 28 storybuilding, it is reasonable to consider that the entire length of the wall flange has been mobilized andcan be used for the design of the core.

The sample spreadsheet in the report has been corrected. The corrected results do show a significantdifference in axial load for the + and - load combinations. An updated spreadsheet is included inExhibit 38. There was no significant change in the vertical wall reinforcement.

Exhibit 38

11/17/17 Please provide the associated updated drawings that will correspond to the revised reinforcing shownin Table E38.1

11/20/17 Please see the Phase I (Foundation) Permit drawings attached to this response. Ph. I dwgs

11/30/17 On the updated drawings sheet S3.02, it shows vertical bar callout V2 (#8 @ 12") initiating above Lvl1.In the calcs and on the other walls, it appears that (#7 @ 6" ) continues up through Lvl 5. Pleaseupdate or clarify.

12/16/17 This was caught and has been updated. Please see the Phase II Permit drawings included with thisresponse.

Ph. II dwgs



Calc Section 8 (WallShear)

09/08/17 Please clarify if all representations of Vu in this section already include the 2.5 factor amplification 10/30/17 This section has been updated to include the 2.5 factor on the DE earthquake shear demands. Pleasesee Exhibit 41 and the response to Comment 41.

Exhibit 41

11/17/17Comment Resolved- See Comment #41



09/08/17 Phi is shown as = 0.4 on Table 8.5. Please clarify how this value was obtained. Was it applied to bothDBE and SLE? If this is where the 2.5 factor was applied, it appears to be based upon a phi=1.0 (where1/2.5=0.4).

Please also provide a sample hand calc for one of the typical rows in this sheet. For reference, whenLev 07 is spot checked given the prescribed thickness, length, and rho: Even if a φ=0.75 is used insteadof φ=0.6, φVn=2415k <2.5*Vu=3212k

10/30/17 The previous results were incorrect. Please see Exhibit 41 for updated demands and reinforcement.For this set of results, the 2.5 amplification of DE has been performed in ETABS and the reinforcementwas designed using these amplified Vu forces. The 2.5 value isn't a strict application of over-strength,but is selected based on previous experience with similar buildings as a best estimate of forthcomingMCE results. It will either be validated or modified in the MCE analysis.

Using the above loads, the phi factor has been set to 0.6. A sample calculation is shown in Exhibit 41

Exhibit 41

11/17/17 Please provide the updated version of table 8.5 along with the plots provided as part of Exhibit 41. 11/20/17 Please see Exhibit 41.1. Chapter 8 of the DE/SLE package has been reproduced in its entirely includingthe updated amplifited DE results.

Exhibit 41.1

11/30/17 Regarding the updated Table 8.2: Use of a phi=0.6 would imply that Vu should be limited to8rootf('c)*phi=4.8root(f'c). It appears that some of the values in this table (near the base of the Southwall and near L6 of the west wall) meet or exceed this limit. While it is understood that these arebased upon empirically amplified shear demands, it is worthwhile to take a closer look at these walls asit may indicate potential issues at MCE. Also, given that the Seattle Building code would requirespecial shear walls over 160' tall to apply Ω to shear demands, it would seem applicable to maintainthe amplification while meeting the stress limit.

01/29/18 The wall shears meet the Seattle Building code limits using omega = 2.5 and phi = 0.75 (Vu =6root(f'c)). Further, the MCE demand/capacity ratios are all acceptable (see MCE package, Figure 110s)




09/08/17 Please clarify if f'c was used for Table 8.2 (DBE), and f'ce used for Table 8.3 (SLE). 10/30/17 F'c was used for both (per ACI for DE and per TBI Section 5.7.2 for SLE).



Foundation andTransfer Diaphragm

09/08/17 It is understood that the provided calculations for these components are intended as preliminary sizingto be confirmed at MCE. Once the MCE analysis and associated design has been completed, will thesecomponents also be confirmed at the SLE/DBE levels of analysis?

10/11/17 Yes, the design will be confirmed for the DE, SLE and wind strength analyses. These results will be partof the MCE package.

11/17/17

Comment Resolved- to be confirmedat MCE package


Transfer Diaphragm 09/08/17 Provide calculations (to be confirmed at MCE) that show the transfer of drag forces into the verticalcore wall components that they connect to.

11/03/17 Please see Exhibit 44 for the preliminary diaphragm calculations using 2.5DE. Exhibit 44

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11/17/17 Was the compression component of drag forces evaluated as well? Is confinement triggered?These are understood to be preliminary checks, with a more thorough evaluation expected to beperformed in future packages

11/20/17 Further diaphragm checks will be performed for Level 1 and at MCE. For the foundation permit, LevelP1 has the highest diaphragm loads for below grade levels (see Exhibit 45, Chapter 7 from thefoundation permit calcs):1) For loading in N-S direction, the maximum compression is at the east wall, with amplifiedcompression = 1839 kips. Using the increased limit of 0.5f’c per ACI 318-14 18.12.7.5 due to theconsideration of amplified design force and effective slab width: 0.5f’c*t_slab*(t_wall+8*t_slab) =0.5*6ksi*10”*(30”+8*10”) = 3300 kips >= 1839 kips. Therefore, no confinement required.2) For loading in the E-W direction, the maximum compression is at the north wall, with amplifiedcompression = 1490 kips. Similar to above: 0.5f’c*t_slab*(t_wall+8*t_slab) = 3480 kips >= 1490 kips.Therefore, no confinement required.

12/01/17 Per response above, further diaphragm designs (for all diaphragms) will be expected with the MCEpackage (along with a more in-depth review). However, based upon the infromation provided,specifically related to the P1 slab as an example:

1) On Sheet S2.P1R, an opening is indicated along the south core wall. This opening is not shown onfloorplans on Pgs. 706 and 708 of Chapter 7. Was this opening accounted for in shear friction rebarinto this southern wall (as shown on Pg. 708) or the chord reinforcement shown going through thisopening on Pg. 706?2) Multiple callouts in the drawings do not appear to the match the calculated rebar shown on Pg. 706and 708 including a) Chord Bars D136 along eastern wall b) N-S drag rebars into core wall. PLeaseconfirm all callouts3) Please confirm that the lengths of collectors into the shear walls is justified as adequate enough tocollect/distribute the loads into the full length of the wall.4) Please clarify how the distribution of demand between shear friction and drag bars wasdetermined.5) Please clarify how the "Max Vu/ft in Shear Friction" was determined (for example, the 132k/ft valuefor the P1 slab shown on Pg. 703)

02/22/18 Note: it is understood that this question pertains to the Phase I Permit Calcs dated November 16, 2017(not the DE/SLE submittal)

1) This opening no longer exists - please see the updated drawings (Superstructure Permit set)submitted with this response.

2) The Superstructure Permit drawings have updated these marks. A few other minor changes havebeen made to callouts for the next set of drawings.

3) Please see response to Comment #86.

4) An even distribution of force was assumed along the length of the diaphragm, i.e., the same rate ofshear per foot is resisted by both sets of collector bars and the shear friction bars at the wall face.

5) The max value is the upper limit on allowable shear, per ACI 318 Section 22.9.4.4



Additional Items 09/08/17 For DBE/SLE checks, please also provide:-Column Evaluation @ SLE only-Typical diaphragm design-Basement Wall Design

11/03/17 These checks are currently being prepared for the foundation permit set to be issued on November 16.We will forward Exhibit 45 when complete.

x

11/17/17 Pending Exhibit 45 11/20/17 Please see Exhibit 45 and the attached Phase I Permit calculations. Applicable Phase I Calcs are asfollows: Chapter 4 - Basement Walls, Chapter 5 - Columns, Chapter 7 - Below Grade Diaphragms.Exhibit 45 contains a sample SLE column check and an elevated diaphragm design calculations.

45,Ph. I Calcs

12/01/17 1) Exhibit 45 and the Phase I calculations only provide finalized SLE column calculations below grade.Are the above-grade column final calculations still forthcoming (they are only noted as for reference inthe Phase I calculations).

2) For the typical diaphragm design, please include the calculations used to develop the diaphragm Fpforce at each floor. Is any amplification included as part of this diaphragm demand? As noted in othercomments, it is expected that additional diaprhagm evaluation/design will be presented in futuresubmittals.

3) For the typical diaphragm check, the length of west wall not adjacent to openings is used to delivershear friction. The openings will prohibit the diagonal shear strut from forming along this wall,prohibiting this load path unless it is shown that the typical diaphragm grid of steel can provideadequate load path to deliver the shear between the openings (or supplemental steel is provided).

4) For the typical diaphragm check, it appears that Φ=0.75 is used. Per ACI 318-14 21.2.4.2, Φ fordiaprhagms for shear shall not exceed the least value of Φ for shear used for the vertical componentsof the primary seismic force resisting system (Φ=0.6).

01/08/17 1) Yes, above-grade SLE calculations are included in the superstructure permit set (submitted with thisresponse).

2) Diaphragm Fp force was determined per ASCE 7-10 12.10-1. The code-level inertial diaphragmforces were not amplified. See Exhibit 45.1 for further explanation.

3) Shear friction at west wall was not used to deliver diaphragm forces into the core wall due to themultiple openings. See Exhibit 45.1.

4) The diaphragm calcs have been updated to use 0.6 for shear. See Exhibit 45.1.

Phase II Calcs,Exhibit 45.1

03/20/18 1) SLE above-grade column calculations missing - awaiting submission

2) Were collectors designed to the load combinations of ASCE 7 12.10.2.1? The calcs appear to bebased upon the Fpx demands alone.

3) Closed

4) Closed

04/20/18 1. Please see Exhibit 45.2 for sample column calculation for SLE.

2. Please see Exhibit 45.3 for a tabulation including the collector check from ASCE 7 Section 12.10.2.Both MCE and code loads are shown - diaphragms have been designed for the higher of the loads.MCE level loads control all cases except Level 27 in the Y direction.

Exhibit 45.2

Exhibit 45.3

05/18/18 1) Closed

2)a) The exhibit only compares 1.3*MCE vs. Ω*Fp (from DBE analysis), but does not address the potentialload combinations from ASCE 7-10 Section 12.10.2.1, including forces determined directly from theanalysis (in lieu of Fp). Does the Fp force conrol over forces from the analysis? Please confirm orclarify.

b) The sample calculations shown in Exhibit 45.3.1 show B=1.17 for slab shear and bearing instead ofB=1.0 per Exhibit 80.1. Similarly, please justify slab bearing utilizing a φ=0.75 in lieu of φ=0.65 similarto diaphragm collectors per Exhibit 80.1.

05/29/18 2a) Please see Exhibit 45.4 for updated calcs including the results from the DE analysis.

2b) The phi factor has been revised to 0.65. The bias factor for bearing was not included in 80.1 and isequal to 1.17 - this number has been subsequently used instead of 1.0. Correcting the phi factor andusing the higher bias factor results in a net capacity slightly higher than the previous calc, therefore thedesign was not impacted.

Exhibit 45.4

06/12/18 2)a) It is suggested to utilize mass*diaphragm acceleration (from the linear dynamic analysis) in lieu ofstory shear differential. It appears as though these demands would still likely not govern over Fp, butplease confirm.

b) Both the φ=0.65 and the B=1.0 referenced in the 05/18 comment were referenced from the Exhibit80.1 table, from the "Diaphragm Collectors (Compression)" row. Please clarify why for these calcs thebearing is treated with a B=1.17 compared to the majortiy of other actions, including collectorcompression, that utilize B=1.0 per Exhibit 80.1

06/15/18 2a) Please see Exhibit 45.5 for story forces comparison using results from different methods. Aspredicted, acceleration*mass with linear analysis results will not control over the MCE results.

2b) This table had been updated, but didn't make it into Exhibit 45.4. Please see 45.5, where bearing iscalculated as 1.17.

Exhibit 45.5


Submittal: MCE Package (11/23/17; 12/11/17; 02/26/18)

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46 MCE Submittal(12/11/17)

Model - Plastic HingeStrain Monitoring

12/14/17 It appears as though the first story in the NL model is meshed at midheight, and the story includes twostrain gages over the height. Please confirm that results from this story are coming from the lower ofthe two strain gages.

01/08/18 We confirm that there are 2 strain gages within the first story, i.e. from Lev 01 to Lev 02 [gages from Z= 864 (upper Lev 01: top of Lev 01 "stubwall") to Z = 956 and from Z = 956 (approx mid-height) to Z =1026 (Lev 02). Results are coming from both of these gages. For clarification, another gage is presentfrom Z = 796 (lower Lev 01: bottom of Lev 01 "stubwall") to Z = 864. [See EXHIBIT 46a for overview.]

It is noted that MKA has revised our model to address a modeling "compatability" issue associatedwith the Lev 01 "stubwalls". Because they were modeled with elastic properties, their presence acts asa "hard point" at the NW and SE corners of the core (thru the height of the "stubwall". Accordingly,we revised our model to include nonlinear vertical fiber properties in these "stubwalls" similar to thecore walls to which the "stubwalls" are connected.

As the above-described modeling revision has an anticipated impact on the strain distribution withinthe plastic hinge region, we have attached revised tension strains in EXHIBIT 46b and revisedcompression strains in EXHIBIT 46c.

Exhibit 46

03/20/18 Regarding the stub wall modeling: Given that these components have now been provided nonlinearproperties, please clarify how they are evaluated for acceptance. Also, given that it appears that thecomponents will reach post-yield demands, please clarify how this yielding behavior is expected toimpact these components' performance as a collection component.

04/04/18 The stub walls adjacent the shear wall (Beams B70A and B80A) are acting compositely with the corewalls by virtue of their interconnection and therefore the core wall strain limits are applicable over alocalized portion of the stub wall. Given the nonlinear behavior with vertical tensile yielding and thestub wall/deep beam acting as both a constraint (vertical) on the core wall and a drag element,reinforcement and confinement equivalent to the Level 1 core wall was employed. Beam stirrups at 4"on center, side bars at 5 1/2" on center, and full confinement ties over a region equal to the depth ofthe beam have been provided in order to assure robust and ductile performance at and near the jointwith the wall (see Exhibit 46.1).

Exhibit 46.1



Model - GravityLoading

12/14/17 It appears that all gravity loading is applied as point loads. How is gravity loading represented on theslab-beam elements, as this will impact their initial flexural demand?

01/08/18 As you have indicated, gravity load is applied as nodal point loads at column and core nodes. Line loadhas not been applied to the slab/beam frame elements as this load has been encapsulated in theapplied point loads. Accordingly, there are no resulting gravity induced shears or moments in theoutrigger slab/beam elements, e.g. parabolic moment profile along length.

More importantly, there is also no gravity induced shear or moments in these beams resulting fromdifferential vertical movement of the core and columns, e.g. uniform shear profile. This wasaccomplished by utilizing the Perform capability for "deleting these elements for gravity load". Thus,initial gravity conditions have been set to zero for the beams, i.e. initial gravity end moments at beamstart and end nodes.

These were intentional modeling decisions in recognition of the following:

1) Capturing the "true" gravity induced shear from differential movement in the column and core isdifficult and highly approximate, i.e. effected by end fixity, time-dependent creep, shrinkage, etc.

2) While neglecting the initial end moment conditions represents a shift such that initial "yielding"may be delayed or accelerated, the overall hysteretic energy dissipation and effective stiffnesscontribution are similar with or without refinements to outrigger beam initial gravity conditions.

03/20/18 Given that multiple outrigger hinges are relatively close to the 0.05 rotation limit, it appears prudent toensure that yielding activation is more accurately captured by including representation of initial gravitydemands. It is acceptable to not include the outrigger beams in the gravity analysis, however thebeam hinges themselves should be modified, as discussed in ASCE 41-13 10.4.4.3 in order to accountfor the initial demands.

04/20/18 This would be a very detailed undertaking that we feel is unnecessary. The slab/column connection isdesigned to remain elastic under gravity loads and therefore no plastic rotation will occur prior toearthquake loading. The cited rotational limit of 0.05 from ASCE 41-13 Table 10-15 is a plastic rotation,whereas the reported rotations are total rotations. Even if a joint went immediately plastic under asmall drift, it would remain within limits. Further, the slab testing in Klemencic et al, 2006 (see Basis ofDesign references), which had similar spans to the Ninth and John building, did not indicateslab/column joint failures for drifts up to 5%, which are far larger than the mean transient drifts of <1.5% in this building. Slab/column joints are reinforced with stud rails regardless of gravity demands toensure this ductile behavior at the joints.

03/20/18 The main concern was in areas where reported rotations are already relatively high (i.e. > 0.04) -although drifts are closer 1.5%, this does not consider the rotation due to differential verticalmovement of the core vs. columns, so the rotation is the best reprentation of behavior.

It is agreed that given how quickly the slabs yield, modification to their strength would likely not resultin substantial differences. However, it may be recommended to provide some supplementary bars (ora slightly tighter spacing) at the dowel bar connection from the slab to the wall at the locations wherethe rotations are high (e.g. > 0.045) , particularly in light of Comment #48.

05/28/18 Per Exhibit 48, the "Start" values for the outriggers beams (conditions at slab/core joint) are all <=0.045. (see Figures 48b, 48c (long period) and 48f, 48g (short period)). Only one slab/core rotation isgreater than 0.035 (NE corner of core at Level 28), and bottom dowel bars at this location at Level 28are at half the spacing of the typical level. Finally, since we are using detailing commensurate with thetest, we argue that additional reinforcement is not required.

06/12/18 Comment Resovled


Slab-Beam Outriggers 12/14/17 Please provide the results (rotations) from the slab-beam outriggers, as well as the comparison totested results (to determine ultimate deformation capacity)

01/08/18 1) Detailed floor by floor summaries of slab beam outrigger rotations as well as a comparison withthe ultimate deformation capacity (0.05 radian rotation) is provided in EXHIBITS 48b thru 48j.

2) A key plan with beam names is provided in EXHIBIT 48a.

3) A summary of rotations at a sample floor is provided in EXHIBIT 48k.

Exhibit 48

03/20/18 1) through 3) are closed

4) Please provide updated summary plots after consideration of Comment #47

5) Please clarify how the flexure capacity of the slab is developed at the column end of the outriggerslab. The situation at the column is different than the wall where all rebar across the slab strip areanchored into the wall to provide the flexural capacity.

6) Rotations of the slab appear to be non-negligible, in the 3-5% range particularly in the upperportions of the buidling. When these rotations occur, only a portion fo the slab thickness remains incontact with the shear wall as cracks open. Given this, please discuss/justify the concurrent use ofthese same zones to transfer in-plane diaphragm shear through shear friction (in the perpendiculardirection). Perhaps it is appropriate to limit the shear friction capacity to account for a certain % of thecross remaining in compression under these types of rotations - please discuss or propose anapproach.

04/20/18 4) Based on the response to Comment 47, the current summary plots are still applicable.

5) The two-way slabs act as equivalent frames whereby moment is transferred to the column via anequivalent column with torsional members (as defined in ACI 318-14 Section 8.11). All reinforcementand PT in this column strip is effective. Additionally, all columns above the seismic base are reinforcedwith stud rails per 18.14.5, which will provide the ductility to maintain integrity at the slab/columnjoint during a seismic event.

6) There is reserve capacity in the shear friction calculations that can be used to address thispossibility. A mu value of 1.0 has been assumed in the design (ACI Table 22.9.4.2). In actuality thecontractor with pour the walls floor-by-floor, so this joint will be poured monolithic and could havebeen designed with mu = 1.4. This gives 40% reserve capacity.



Slab-Beam Outriggers 12/14/17 Please provide the results (rotations) from the slab-beam outriggers, as well as the comparison totested results (to determine ultimate deformation capacity)

12/16/17 Repeat of comment 48.


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8 of 19


Concrete Modulus(Section 2.2.1)

12/14/17 Justify the use of the concrete modulus of elasticity equation referenced in this section in lieu of theequation often referenced for high strength concrete (per ACI 363R-92, also referenced in LATBSDC2017 Table 3).

01/08/18 Our understanding is that the LATB equation for high strength concrete was implemented as a result ofpoor quality aggregate in the LA region leading to lower Ec test values. In Seattle, where pooraggregate is not an issue, ACI 318-14 Equation 19.2.2.1 has been used successfully to estimate Ec. Wecan gather and supply modulus test data for Seattle mixes upon request.

03/20/18 Please supply the modulus test reports relevant for this project for review 04/23/18 Please see Exhibit 50 for sample Ec data for the Seattle area. The sample test data tracks the ACIequation quite well - an average difference of less than 0.5%.

Exhibit 5005/18/18 Comment Resolved


Coupling BeamCalibration

(Section 2.2.2)

12/14/17 Figures 25 and 26 compare the coupling beam backbone calibrated to test results. The calibrationincludes a 0.25FU residual strength.

PEER TBI Section 6.8.2 defines δu as the mean value at which substantial loss of capacity occurs (whichwould essentially match the DL point in the Perform backbone curve). This same section also notesthat if δu is exceeded in any of the time histories, either the analysis is consider to have anunacceptable response, or the strength associated with this deformation should be negligible for theremainder of the analysis.

Although based upon these initial results, it does not appear as though any coupling beams reachbeyond the δu value, in order to be consistent with this TBI section, please update the residualstrength in the backbone to represent negiglible strength beyond δu.

02/22/18 The du limits of 0.04 and 0.06 for conventional and diagonally reinforced beams respectively were notreflective of PEER TBI version 2. We have revised these du values to 0.06 and 0.10. Also note that thedu value for steel coupling beams is 0.085 (see MCE Addendum 1). In this way, these values arereflective of the limits for "valid range of modeling", e.g. du per figures 4-3 and 4-5 in PEER TBI. Seeupdated Basis of Design.

Basis of DesignV04




(Section 2.2.2)

12/14/17 Figure 26 compares the calibration of the Perform backbone to test data for the conventional couplingbeam. It appears as though the Perform backbone maintains a slightly larger strength than the testspecimen at about 2% rotation and beyond - perhaps use of 1.10Vy would be a better fit than 1.15Vy?

01/25/18 We agree that a 1.10Vy value may be a better fit and will update the model. Exhibit 52 also shows thisupdate.

Exhibit 52

03/20/18 Exhibit 52 appears to still reference Vu=1.15Vy - please confirm or clarify. 04/04/18 At first glance there appears to be no change. However, there are (2) issues at play: the commentabove regarding 1.1 vs 1.15 for Vu and the comment regarding fye = 70 ksi (Comment #54). In regardto fye = 70 ksi, the value for Vy was revised from 1.25 x 2 x Mn / L to 1.167 x 2 x Mn / L. This changecarries thru to the Vu such that and aded reduction from 1.15 Vy to 1.10 Vy would be double counting.




(Section 2.2.2)

12/14/17 Please provide a sample hand calc that determines the capacites of the sample coupling beam shownin Figure 27 and 28. Please also include the sample calc which determined the effective deformationsthat correlate with the rotations (DU and DX).

01/08/18 See attached sample calculations showing capacity calculations for a sample diagonally reinforced linkbeam and a sample conventional reinforced link beam (EXHIBIT 53a and 53b).

Note that figures 27 and 28 from the MCE calc package had been illustrative examples not from thisproject. These figures have been replaced with representative beams from this project (EXHIBITS 53cand 53d).

Exhibit 53

03/20/18 Please also include the sample hand-calc which determined the effective shear deformations thatcorrelate with the rotations (DU and DX)

04/04/18 See revised figures 53a and 53b (Exhibit 53.1), which show sample calculations (added with clouds). Exhibit 53.105/18/18 Comment Resolved



(Section 2.2.2)

12/14/17 In Figure 27, please justify the use of fye=1.25*fy=75ksi, in lieu of fye=70ksi per PEER Table 4-2. 01/25/18 The Perform model will be updated to match the Basis of Design: fye = 70 ksi per PEER Table 4-2 inconjunction with the revision suggested in comment #52 (see Exhibit 52).

Exhibit 52



Slab-Beam Outriggers(Section 2.2.3)

12/14/17 Similar to the coupling beams, please provide the calibration data used for the slab-beam backbones.Also, see Comment #51 regarding strength beyond δu, similar for the slab-beams.

01/08/18 We have compared beam rotations against a 0.05 radian rotation limit (see response to comment#48). Exhibit 55 presents the test and calibration data used as rationale for the limit.

Exhibit 55



Slab-Beam Outriggers(Section 2.2.3)

12/14/17 Please justify the use of multiple outriggers, including those coming off the core at an angle, as shownin Figure 39. Given that the beams are not completely orthogonal, please clarify howyielding/degration in these elements can be accurately represented when their areas potentiallyoverlap. do portions of the slab end up double-counted? Please provide the related calculations usedto determine the properties of these slabs, including accounting for the openings along the westernedge of the core.

In addition, please justify their use at locations that are not specifically related to slab between a corewall and a column (such as "N", "J","G", "H1", "H2", and "J"). Do these beams utilize a similar propertyas those provided between the core wall and columns?

01/25/18 Multiple outrigger modeling approach:The modeling approach with mulitiple outriggers coming off the core was taken primarily for thebenefit of being able to extract explicit seismic axial demands on individual outrigger columns.Slab/beam calculations considered the potential overlap issue you are describing so as to avoid anypotential double counting. See Exhibit 56 for relevant calculations.

Column to column outriggers:Properties for the column to column slab/beam elements are calculated similarly to core/columnslab/beam elements. These were also modeled to capture potential "frame action" that could alsoengage these "outer" columns as outriggers. Again, explicit seismic axial demands can be extractedwith this approach.

Exhibit 56



Story Shears(Section 4.1.1)

12/14/17 Figures #51 and #52 show core shears greater than the overall building shear. Please confirm thebehavior here - is this a figment of averaging? Or is a certain amount of shear going into the columnsat this floor?

01/08/18 The issue(s) here is not due to averaging. There is shear present in the columns at the ground floor(ETABS Lev 02) as you have indicated. Columns that "sit atop stubwalls" see particularly pronouncedseismic shear. In a sense, these columns are cantilevered up off the stubwall. Some other columnssee moderately high shears just due to their orientation, e.g. shear along relatively deep 48" columns(this may be in the X or Y direction). Other isolated columns see high shear loads associated withcolumn knuckles.

The following has been provided to better illustrate the behavior:

1) A summary of individual column shear loads (max of 11 for Long Period CMS and Short PeriodCMS) is provided in EXHIBIT 57a and 57b respectively.

2) A time history plot is provided in EXHIBIT 57c. The intent here is to illustrate the shear reversalbehavior that occurs. Examining a "snapshot" at T = 35.0 sec, core shear and column shear have thesame sign at ETABS Lev 02. Shear is being taken by the columns. At ETABS Lev 03, the column shearshave opposite sign as the columns at ETABS Lev 02, associated with a backstay type effect of thecolumns. Noting that building shear = core shear plus column shear at this level, the core shear isactually larger than the building shear.

3) A free body diagram associated with the time history plot is provide in EXHIBIT 57d.

4) A summary of column loads associated with the time history plot is provided in EXHIBIT 57e.

Exhibit 57

03/20/18 Behavior is understood and agreed upon, however comment will remain open until confirmation thatcolumns have adequate capacity for these demands (see Comment #113)

04/04/18 See response to comment #113.

05/18/18

Comment resolved- see comment#113 for columnevaluation

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Story Shears(Section 4.1.1)

12/14/17 The average building seismic shear in Figure #56 shows a slight decrease in average story shear directlybelow grade - however this same reduction is not seen in Figure #52, which also shows average overallbuilding shear - please clarify.

01/08/18 This was erroneously presented; there should not be a reduction in building shear. This apparentreduction was the byproduct of elements accidentally not included within the building section cut atthis level (ETABS Lev 01, beneath Lev 01 floor). Specifically, some of the "stubwalls" were not includedin the builidng section cut at this level.

It is noted that there is a reduction in core shear at the ground floor (ETABS Lev 02). This is describedin the the item 57 response.

Finally, in light of the modeling revision described in comment #46 ("stubwall related"), revised shearand overturning plots are being provided (see EXHIBIT 58a and EXHIBIT 58b). This includes the revisedfigure #56 with the section cut correction.

Exhibit 58



Peak Displacements(Section 4.2.1)

12/14/17 Figure #73 shows one short period CMS motion that results in a larger X-direction roof displacement(~70") that it's associated long-period CMS motions in Figure #72 (~58"), which is not intuitive. Figure#75 similarly shows a similar short period record in the Y direction resulting in a larger displacementthan the long-period CMS motions. PLease carefully review these two particular cases.

01/08/18 We reviewed the cases and can find no abnormalities. Note that in some cases the long period CMSdisplacements are higher than the short period CMS displacements and in other cases they aresmaller. The cases that you have cited are not necessarily "outliers".



Coupling Beams(Section 4.2.3)

12/14/17 Coupling beam rotations appear relatively low (less than 1/2 of the acceptable rotations) - is this just afigment of the minimum strengths set at SLE/DBE?

01/08/18 Yes, correct.



Concrete Strains(Section 4.2.5)

12/14/17 Strains appear very low - to the point that even the maximum results would all essentially meetacceptance with unconfined concrete, which is not intuitive. Please justify that the strains presentedare accurate in their current representation.

02/20/18 The low strains observed are not unusual for a core wall structure. In this case, wall rebar is fairly light.Given that the compressive load that actually gets “delivered” to the walls is “capped” by the amountof opposing tension in the vertical reinforcement, resulting strains are low. The attached exhibitprovides sanity calculations that illustrate the situation and behavior at play.

Exhibit 61

03/20/18 To ensure that strain localizations are not being missed, please provide a parametric study that dividesthe vertical height of all core wall elements in half from P2 through Level 7, perhaps just running oneof the more critical ground motions for strain such as "1-11 Maule-SPA" for a before/after comparisonof the wall strains.

04/24/18 MKA has previously done an in-depth study of the effect of core wall element meshing anddetermined it has a negligible effect on strains. Please see Exhibit 61.1 for the study.

Exhibit 61.1

05/18/18 The parametric study provided in Exhibit 61.1. generally focuses on overall averaged differences overthe global behavior of the building, which are shown to be relatively negligable as expected. It is alsoagreed that tension strains are low enough to the point that tension strain acceptance limits would notbe a concern, even given an increase in strain.

The main related concern regarding tension strain would be for the few locations new the base of thecore (See Tensile Strain points 8 and 20 from Exhibit 46b from the 01/25/18 submittal) where averagetensile strains are close to 0.01, the limit which can potentially impact allowable shear strength (1.5xmultiplier per PEER TBI 4.6.5.6).

For reference, the model we have received was re-run with a revised mesh at the lower 3 floors (~40"tall = 4 elements at 1st story, 3 elements at 2nd and 3rd story). One of the worst-case strains from theprovided results (Strain Point 8 for "1-4 Kern") was tracked to compare and was found to increase from0.02 to 0.04 at the bottom of the first story. If similar increases are found from other records, thiscould indicate that a more refined measurement of strain could potentially reveal locations withaverage shear strain beyond 0.01, impacting the allowable shear capacity in these areas.

Please either:1) Compute the average strains (Long Period Suite only) based upon a refined-mesh model (in therange of 40" tall elements, only necessary at potential hinging zones such as the base).2) Justify the use of the 1.5x shear amplication given other references/test data that show similarshear capacity at the deformations currently determined for 9th & John.

05/29/18 We have not used the 1.5 amplifier in regions where high strains might be expected (Level 1 throughLevel 5) - see p. 115 and p. 128 of the original MCE package.

Orignal MCEpackage

06/12/18 Although the table on Pg. 128 of the original MCE package did utilize a 1.0 amplification on Lev 1through Lev 5, the same table that was later re-produced as part of Exhibit 65.1 has utilized a 1.5amplification - please clarify.

06/15/18 We stand corrected - we did use 1.5 in the updated design. However, we also provided enhancedreinforcement in the hinge region from Level 1 to 4. In the attached Exhibit 61.2, the factor on Rn,exphas been reduced to 1.0 from Level 1 to Level 2 where tensile strains are highest. The Exhibit showsthat the shear capacity of the wall is acceptable. The current shear wall elevations have been includedin the exhibit for reference.

Exhibit 61.2

06/26/18 Focusing on the West Wall at L1-L2, given that this is where the highest DCR's occur, please confirmthat the rebar as shown on the attached elevations at this location (3 #7 @ 4" O.C.) stays within thetypical Vn<10rootf(c') limit, or that if Vn is limited to 10root(f'c), shear DCR is still < 1.0.

06/26/18 Please see Exhibit 61.3. Exhibit 61.2 has been updated to include the table of checks on 10sqrt(f'c). Theprovided reinforcement is in all cases below the cap on Vn.

Exhibit 61.3

07/08/18 It appears that 10root(f’c) per individual pier has been checked and verified per ACI 318 18.10.4.4 asshown in Exhibit 61.3. Was 8root(f’c) for all walls sharing a common lateral force per this same ACIsection also confirmed?

Pg. 11 of Exhibit 61.3 would indicate an average of the western and eastern walls > 8root(f’c),however perhaps when evaluated at a time-step basis, these average stresses remain under 8root(f’c).Can you please verify within a revised Exhibit 61?

08/28/18 As stated in the above answer on 6/15/2018, we have shown that the shear capacity is adequate atLevels 1 and 2 taking a voluntary 50% reduction by using 1.0 instead of 1.5 factor on Rn,exp, eventhough the walls have low compression strains. We still contend that using a 1.5 factor is appropriate,especially in response to your latest comment. Exhibit 61.4 shows the wall strains and the rationale forusing 1.5 for all walls. The wall shears shown on p. 4 of the Exhibit are all less than the 8root(f'c)threshold.

Exhibit 61.4

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10 of 19

09/11/18 Commentary: Original response to the concern about strain measurements (05/29/18, with followupon 06/26/18) was that a 1.5 amplifier would not be used at the few lower levels. Recent responsefrom 08/28/18 indicates that the 1.5 amplifier will indeed be utilized, in order to meet the average8root(f'c) threshold.

The peak strains (which would prohibit the 1.5 amplifier) appeared predominantly confined to thenorthwest corner of L1 given the opening located there. Therefore, it would appear that even if thiswestern wall did not receive the 1.5 x amplifier, but the eastern wall with lower peak strains did, thenthe average 8root(f'c) threshold would be met.

Therefore, this commentary is only provided for reference - comment can be considered closed.09/11/18 Comment Resolved


Concrete Strains(Section 4.2.5)

12/14/17 The only spike (although still relatively low) in concrete strain occurs in Figure #95, at the northwestcorner of the core. Is this at the location of the adjacent opening in the west wall?

01/08/18 Confirmed. This spike occurs at the location adjacent the opening in the west wall.



Gravity Columns(Section 4.2.6)

12/14/17 From the layout graphic of the outriggers, columns "B" and "C" on the north side of the core appear tobe relatively symmetrically placed. However in the axial demand table, column "B" is seeing about 3xgreater axial load than column "C" - please clarify. Note that the same action is seen between column"L" and "K" on the south side of the core.

01/08/18 The seismic axial demands are actually similar for columns "B" and "C" (i.e. within 20%approximately)...with one exception. The same is true for columns "L" and "K" (reference Figure #102and #103 in MCE calculation package).

The exception occurs beneath Lev 01, where there is a difference in column axial loads. This isbecause columns "B" and "K" are engaged as outriggers via "stubwalls" (30"x70" and 30"x80" deepbeams respectively) at Lev 01, resolving forces thru the Lev 01 diaphragm. Thus, relatively substantialadditional axial demands are imposed on these individual columns beneath Lev 01. For clarity, a figureillustrating the outrigger condition is shown in EXHIBIT 63a.

Also, it is noted that there were a few beams at the roof level that were oriented incorrectly,ultimately effecting the axial loads induced into the gravity columns. This was revised and a new set ofcolumn axial loads has been extracted. This loads are included within EXHIBIT 63b.

Exhibit 63



Gravity Columns(Section 4.2.6)

12/14/17 (Also see comment #56)

Although the intent of the outrigger beams is to adequately capture the outriggering action of the slaband gravity columns, there are a few locations in the layout which include an additional bay ofoutrigger slab out to an exterior column ("N", "G", and "J"). The table indicates that these exteriorcolumns end up seeing greater axial demands than their associated interior columns - is this stilloutriggering action, or is this representing more of a framing effect of the slab and columns?

01/08/18 It is both. Both the inner and outer columns act as outriggers via framing action. Also, see relatedresponse to comment #56.



Core Wall Shear(Section 5.1)

12/14/17 It is noted that Qns (gravity component of wall shear is assumed to be = 0). While it is agreed that thegravity initial shears may not be substantial, please provide this load for confirmation that it will haveno impact on the shear design.

01/08/18 See EXHIBIT 65 for gravity wall shears.

Most wall shears are in the 0-0.1 rtf'c range. There are a few wall locations where wall shears areslightly higher, up to 0.5rtf'c. These include:

1) Lev 03/04 which is associated with a knuckle column condition. All wall shears are less than0.5rtf'c. 2) Lev 01 which is associated with deep beams (modeled as "stubwalls") at slab steps. 3) Lev 28/Roof which is associated with fixity conditions at relatively deep gravity transfer beams.

Exhibit 65

03/20/18 Please include these gravity demands as part of the full load combination per PEER TBI Sect 6.8.3. inthe reporting of results as well as the final wall design and confirm acceptability.

04/04/18 Gravity demands are included in a revised package that demonstrates acceptability (see Exhibit 65.1). Exhibit 65.105/18/18 Comment Resolved



12/14/17 Given a relatively symmetric core that appears to be relatively centrally located within the floorplate,Figure 110a indicates that the west wall sees about 20% more shear than the east core wall - is therean explanation for this unbalance?

01/08/18 At some floors it approaches 20%, but on average the wall shear is about 5% higher in the west wallthan the east wall. Comment #103 provides some insight on why there is somewhat higher shear inthe west wall. As shown in EXHIBIT 103a ("Mass Breakdown at Each Floor"), the mass centroid of thefloor diaphragm (excluding core self weight) is offset about 43" from the center of the core. This isabout 13% of the core width in the X direction. This offset translates into larger demands in the westwall than the east wall.

Exhibit 103




12/14/17 Have the capacities of Table #110n already included the Vn max (15root(f'ce)) where applicable? 01/08/18 The tables have been revised to include the 15 rtf'c limit (see figure #110n in Exhibit 67) and the15rtf'ce limit (see figure #110o in Exhibit 67). Changes from the MCE report have been clouded in redin the Exhibit.

Exhibit 67




12/14/17 In addition to the plots provided, please also provide plots of the "effective" shear stress of1.3QT/(φs*B), which is essentially the required minimum Rn. In this way, maximum shear capacity ofRn can be easily evaluated.

A quick check of one of the higher stressed walls (West Wall at L03), appears to require a shearcapacity greater than 10root(f'c) [Rn=14824k/(30"x458")=1.07ksi vs. 10root(f'c)=0.89ksi.]

01/08/18 1) Per your request, "effective" shear stress plots are being provided in EXHIBIT 67 (figure #110t).Note that all walls have "effective" shear stress [1.3 x Qt / (f x B)] less than 10.0rtf'c.

2) Regarding your "quick check", the 14824 kip value you cited had not been subject to Vne,max.Calculations have been revised to incorporate: a) Vne,max limits of 15.0 rtf'ce throughout.

b) Miscelleneous reinforcing callout revisions.

c) Bubbling where revisions occur.

Exhibit 67


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11 of 19


Basement Wall ShearDesign

(Section 5.2)

12/14/17 This section describes the basement walls (shear) as critical force controlled elements. However, theBOD originally noted this action as an ordinary force-controlled action (which also agrees with PEERTBI). The current approach of critical force control is acceptable, but just pointed out for consistency.

01/10/18 Noted. We have elected to consider basement wall shear as a critical force-controlled action.




(Section 5.2)

12/14/17 This section describes the basement walls (shear) as critical force controlled elements. However, theBOD originally noted this action as an ordinary force-controlled action (which also agrees with PEERTBI). The current approach of critical force control is acceptable, but just pointed out for consistency.

12/16/17 Repeat of comment 69.




(Section 5.2)

12/14/17 Did the design of the horizontal rebar in the walls account for stresses induced from resisting out ofplane soil pressures?

02/22/18 The horizontal reinforcement was only used to resist in-plane wall shear and to meet minimum wallrequirements, except for a few selected locations. In general, the walls are considered as one-wayelements spanning from floor to floor and soil loads are resisted by vertical reinforcement. At selectedlocations where floor slab does not exist, the wall was designed as a two-way element and horizontalreinf was used to provide capacity. See Exhibit 71 for a sample calculation at the north wall.

Exhibit 71




(Section 5.2)

12/14/17 Please provide the flexural design of the basement walls, including stresses induced for out-of--planeresistance of soil pressure. Did the design of the horizontal rebar in the walls account for these out-of-plane demands?

01/25/18 This was included in the foundation permit submittal. An excerpt of these calcs is provided in Exhibit72. As discussed in Comment 71, horizontal reinforcement was only used for out-of-plane forces inselected locations.

Exhibit 72

03/20/18 Pgs. 415 and 416 within the exhibit appear to indicate that the vertical bars in the basement wallswere determined from soil loading alone. Were seismic in-plane and out-of-plane flexural demands onthe shear walls considered as part of the confirmation of the basement wall vertical rebar?

12/31/99 The vertical reinforcement was designed for out of plane flexure (moment overturning due to in-planeseismic was done as a post-design check and drive up requirements). The vertical reinforcement wasalso increased if necessary based on horizontal reinforcement to meet the reinforcement limits of ACISection 11.6 (see the last three columns in the Table on p. 413 of Exhibit 72).

05/18/18 It is not clear from the response where the soil and seismic demands fro the vertical bars wereconsidered concurrently - please confirm.

05/31/18 Please see Exhibit 72.1 for expanded basement wall calculations including the PMM checks and addednotes (in red) to calculations previously submitted. See also the updated drawings submitted with thisresponse.

Exhibit 72.1Sheets S3.21,S3.22, S3.31 06/12/18 Comment Resolved


Updated Drawings 12/14/17 Please provide the current set of structural drawings 01/08/18 A copy of the Superstructure (Phase II) Permit drawings has been included in this response. Phase II Permitdwgs



Foundation Design(Section 5.3)

12/14/17 Please provide the SAFE models utilized for the foundation design. Also see Comment #75 02/22/18 Please see the attached SAFE model. Note that the loads in this model will be updated with the finalMCE loads, which we expect to submit by 3/9/2018.

SAFE model

03/20/18 Awating MCE Model. 04/19/18 Updated MCE SAFE model submitted along with Exhibit 74. Exhibit 7406/11/18 1) The SAFE model appears to only have 60ksi rebar defined, and the design strips utilize 60ksi rebar in their

reported designs. It is noted that a majority of the flexural steel of the foundation is 80ksi bar. The plots showndetermining required rebar above and beyond a typical mesh (#11 @6" bottom bars for example) note that this isbased upon 80ksi. Please clarify if/how the 80ksi rebar was represented in the SAFE design in order to determinethe accurate amounts of additional steel required.

2) The default cover to top and bot rebar in the "Design Preferences" of the SAFE model is set to 9.75" Pleaseclarify how this value was determined - is it intended to be an average depth based upon multiple layers of rebar?Does this value hold for all locations throughout the mat?

3)a) For the MCE-X and MCE-Y load patterns: The wall loads appear to include a vertical load on the northernbasement wall (but none on any other basement wall) - is this intentional? Please clarify?b) For the MCE-X load pattern: Distributed flexural demand is only applied to the southern wall, but none isapplied to the northern basement wall. Please clarify.

4) How were the widths of the design strips as shown determined?

5) Sheet S2.P5 notes a built-up slab west of the core, however the load associated with this built-up slab does notappear to be present in the SAFE model. Please clarify

6) The concrete walls at the southeast edge of the core as well as the southeast corner of the mat have not beenincluded in the SAFE analysis. Has it been confirmed that their exclusion results in negilgible difference in therebar layout of the mat?

7) For bottom bars in the E-W direction, there is a final plot that reveals rebar required beyond #11@6" + #18@6".Per S2.P5R, please clarify where on plan both of these layers of rebar are called out. Only MB302 (the #18@6")could be located.

8) Please provide a hand-calc version of the 2-way punching slab check for the first row in the table related to the"Core", including description of how demands were determined for this check.

06/15/18 1) The “Slab Design” tool in SAFE was used to design the top and bottom flexural reinforcement in the matfoundation. A “Typical Uniform Reinforcing” was specified and reinforcement was added where necessary. Thereinforcement demand (in2/ft) from SAFE was multiplied by the ratio of 60ksi/80ksi to get the demand necessaryfor 80ksi rebar. Similarly, when inputting user reinforcement into SAFE, the area of rebar (in2/ft) was multiplied bya ratio of 80ksi/60ksi to get the equivalent area in 60ksi rebar. See Section 3.2 in Exhibit 74 for design showingarea of steel conversions depending on rebar grade.

2) The average depth of (6) layers of #18 with 3" cover (~9.75") was conservatively used as the cover in the models"Design Preferences" throughout the mat. This was to simplify the design without multiple iterations dependingon detailed rebar layers. The cover has been updated to 8” in the transition and 9ft deep mat and 3.6” in the 3ftmat to better represent the rebar detailed on plan.

3a/b) Basement wall MCE loads were extracted from PERFORM and applied as moment line loads on the East,South, and West walls. Due to the irregular shape of the North basement wall, equivalent line loads were used toreplicate the overturning moments in both the x- and y- directions. See Exhibit 74.1.

4) Design strip widths were driven by the modeled mat geometry. Transition zones from the 9ft mat to 3ft matwere modeled as the average of the mat thickness at 5'-0" increments; therefore design strips widths were 5'-0" toavoid station errors in SAFE. The design strip widths at the core were modeled with a width "d" away from thecore edge to better capture the demand. See page 7 of Exhibit 74 for SAFE mat geometry.

5) The addition of 75psf dead load from the Type V built up slab was added to the SAFE model. The combination ofupdating the cover at the transition and 9ft mat and the increase in load resulted in no changes to the matreinforcement as shown on S2.P5R. See Exhibit 74.1 for updated design.

6) The wall at the southeast corner of the core will be jointed at the wall. This wall is only one story tall and muchmore flexible than the 9'-0" mat in this area so will have negligible effect on mat behavior. The corner wall at thesoutheast corner are taller and stiffer relative to the mat. The stiffness and loading of these walls have been addedto the SAFE model. The combination of updating the cover at the 3ft mat and the wall loading has resulted in tochanges to the reinforcement shown on S2.P5R. See Exhibit 74.1 updated design.

7) See Exhibit 74.1 for drawing clarification.

8) See Exhibit 74.1 for calculations and the current slab shear reinforcement plan for reference.

Exhibit 74.1


# Topic& Reference

Date ofComment



Date ofResolution

Resolution/Notes

12 of 19



12/14/17 From the last paragraph on pg. 145, we understand that the presented information to date is intendedto represent the global procedure and general approach to the foundation design, but that furtherinformation including potentially taking advantage of reduction in forces from amplified DE to MCE willbe provided in future submittals. Please confirm if this interpretation is correct, and if so, pleaseensure to include the associated SAFE models that are concurrent with the final design once prepared.

01/10/18 Confirmed, the interpretation is correct. Figures 119 and 120 show the bounded MCE loading. The finalmoments are closer to the lower values, which will lead to a reduction in reinforcement. We aresubmitting the DE SAFE model for reference (Comment 74) and will rerun and update reinforcementper comment 74.

SAFE model

03/20/18 The DBE model does not include the basement wall flexural demands at their base applied to the mat(see #78). Please include as part of the final analysis when comparing against the MCE design (whichshould include both basement wall and outrigger/vert acc column demands per #78)

04/19/18 Column and basement wall demands have been included in the SAFE model. Please see Exhibit 74 forloading.

Exhibit 74

05/18/18 In progress06/11/18 Comment Resolved



12/14/17 In the equations presented for foundation flexure, the "B" bias factor is not included - is thisintentional?

12/16/17 Yes, foundation flexure is considered an ordinary force-controlled action and is governed by TBIequations 6-1 and 6-2, which do not contain a bias factor. See also Exhibit 80.

Exhibit 80

03/20/18 Eqs (6-1) and (6-2) are for force controlled actions with well-defined yield mechanisms (regardless of"critical" or "ordinary" designation), which would not be well-suited for the mat foundation flexureaction. All other force-controlled actions are to satisfy Eqs (6-3) and (6-4), with "critical" or "ordinary"determining the phi factor per Table 6-1 per PEER TBI II.

04/19/18 Load combinations and phi factors defined per TBI 2.0. Please see Exhibit 74. Exhibit 74




12/14/17 It is understood that additional calcs and clarification is forthcoming regarding the foundation - as partof this, please clarify the intent of the upper and lower bound demands discussed in this section. Isthis only intended to be utilized for the current initial submittal?

12/16/17 Confirmed, the bounding was done to establish that the mat design would not significantly increasefrom the foundation permit estimate based on DE demands. After reviewing these comments andmaking any necessary adjustments to the model, a single MCE design will be performed using thebracketed demands from the soft and stiff diaphragm analyses.

final SAFEmodel

(pending)




12/14/17 Please confirm that the final analysis model will include:- Concurrent demands on the basement walls- Column axial demands including outriggering/vertical acceleration effects

02/22/18 Confirmed. Per the response to comment 74, the mat foundation is currently being updated for thefinal design loads.

final SAFEmodel

(pending)




12/14/17 The core stress distribution upon the mat does not accurately represent the true gradient that willoccur at the base of the wall (neutral axis will not be at the midpoint of the wall length). Please updateto a more realistic stress gradient and confirm impact upon bearing and foundation strength.

01/24/18 The foundation will be redesigned with a more conservative assumption in which core moment isapplied as a couple on the two wall flanges (see Exhibit 79).

Exhibit 79



Transfer DiaphragmDesign

(Section 5.4)

12/14/17 From the typical calcs such as that shown on Pg. 161, please clarify how the bias factor "B" is appliedfor the diaphragm capacity checks.

02/22/18 Please see Exhibit 80 for bias factor calculations. Force-controlled critical elements incorporating thebias factor are collector bars, shear friction, and slab shear.

Exhibit 80

03/20/18 1) (See #76 similar):This breakdown appears to be evaluating force-controlled actions designated as"Ordinary" using Eqs (6-1) and (6-2) which are only intended for force-controlled actions with well-defined yield mechanisms, which does not apply to the identified actions in this table. Please updatetable and associated calculations as necessary

2) This table also implies that Qns = 0 in all cases. As noted in #65, this is not always a validassumption, and should be considered as part of the acceptance equations unless justified that gravitydemands for that particular action are negligible.

3) Confirm Rne in this table - it appears this is only considering concrete expected strength, not acomposite representation of concrete + rebar component expected strength typically in the range of1.15. Please confirm if this value was used in any other calculations.

04/24/18 1. Please see updated Exhibit 80.1. Calculations did not need revision and align with the updated table(the B factor used in the calculations is also listed in the table for reference).

2. This table was not meant to reflect Qns. Individual component calculations should be consulted forQns values. See also Exhibit 65 for tabulated gravity demands.

3. Your statement is correct. The table has been updated and composite values have been shown inExhibit 80.1 (note that in some cases a single Bias Factor is only a close approximation and will vary forthe given calculation). Note that in some cases a conservative value of 1.0 has been used.

Exhibit 80.1




(Section 5.4)

12/14/17 From the typical calcs such as that shown on Pg. 161, please clarify what the values for "Reaction onWest Bwall" and "Reaction on East Bwall" represent, and how they were determined - are these fromsection cuts in the Perform model? Are these demands already amplified?

01/25/18 For the design of diaphragm, a simplified beam model is considered. The diaphragm/simplified beam isconsidered supported by the basement walls, while the unloading from the core is considered theapplied point loads. Section cuts from PERFORM model were used to obtain the unloading/point loadsvalue of the core, and the maximum of the stiff and flexible model values was used. These appliedpoint loads were then amplified by 1.3 as shown on Pg. 161 with the "Amplification Factor". The valuesof "Reaction on West BWall" and "Reaction on East BWall" were then obtained by calculating thereactions on the west and east basement wall considering the unloading from the core on thesimplified beam.

03/20/18 Were these values at the basement walls then verified in the nonlinear model? The section cuts alongthe basement walls already appear to be in place in the nonlinear model - were these not used?

04/23/18 Please see Exhibit 81 for updated calculation with consideration of basement wall section cut output.The larger value from the basement wall section cut and the simple beam model was used for eachconditions.

Exhibit 81

03/20/18 Ensure that where this updated the required reinforcement along the basement wall (for example, P4dowels into the west and east basement wall), that the drawings have been updated to reflect therebar. A quick spot check for these specific bars still shows #4 @ 18", not #4 @12" O.C. as referencedin updated Figure 81-2.

05/29/18 This correction has been made. The updated P4 - P1 drawings (in which Perform section cutscontrolled part of the design) have been included with this response.

Level P4R-P1Rdrawings


# Topic& Reference

Date ofComment



Date ofResolution

Resolution/Notes

13 of 19



(Section 5.4)

12/14/17 At the various transfer diaphragms, it appears that there is some shear friction capacity that is beaccounted for that represents transfer from the core wall to the slab on the interior of the wall. Pleasejustify this load path as still sending the shear out to the basement walls in it's various cases

01/24/18 We agree that the interior of core should not be used for the transfer. Please see Exhibit 82 forupdated calculation.

Exhibit 82




(Section 5.4)

12/14/17 As an example, per Pg. 161: For the shear friction steel at core for the west wall, please clarify how thedistribution between shear friction Vu West and Shear Friction Vu East were determined. (Thiscomment applies to all of the similar shear friction calcs). Also see #82 above.

01/24/18 As described in comment #82, shear friction inside the core is no longer used. Please see Exhibit 82 fornew calculation showing the length used for shear friction inside core set to 0.

Exhibit 82




(Section 5.4)

12/14/17 Please include calculations confirming that the bearing capacity of the slab is adequate withouttriggering ACI-required confinement (applies to all of the transfer diaprhagms)

01/24/18 Please see Exhibit 84 for confinement requirement calculation. The depth at some locations at Level P1and 1 is increased in order to avoid confinement requirement.

Exhibit 84

03/20/18 Have the thickened locations referenced within this Exhibit been included in the drawings yet? Theycan't be found on the plans (Phase II permit drawings).

04/23/18 The referenced locations have been checked using a less conservative approach and confinement isnot required. See calculations in Exhibit 84.1.

Exhibit 84.1

05/18/18 The use of 8*tslab (about 56" on either side of the wall) utilizes a larger slab width than may bereasonable for the bearing check. Typically this width is the width of the wall + a portion ofperpendicular wall at the corner (see Tab "Comment #84 for similar figure) - please revise per thiswidth and confirm if confinement is still not required.

06/01/18 The calculations have been updated to use a reduced width. Confinement reinforcement is notrequired (see Exhibit 84.2)

Exhibit 84.2




(Section 5.4)

12/14/17 Please justify not explicitly modeling the ramps between the various transfer levels. Given that theslab extent which represents portions of the ramp are being used for shear friction transfers, won't thisaffect the load path and demands in various diaphragms?

01/25/18 Explicity modeling of ramps in the subgrade levels is not needed in our judgment. Modeling the rampsas flat plate diaphragms provides for the ability to extract transfer forces along the edge of the corewall. They are a reasonable approximation for design purposes and a reasonable simplification of theactual behavior.

These transfer forces are then "carried thru" the diaphragm (from core/slab interflace thru the slaband into the basement walls), accounting for openings, slabs steps, etc. The flat plate modeling hasbeen done in a manner to mimic the stiffness of the actual configuration, i.e. by including "slots" andor openings in the diaphragms. 03/20/18 Comment Resolved



(Section 5.4)

12/14/17 Similar to comment #44, please justify the embedment lengths of all collector rebar into the shearwalls are adequate to transfer the demands into/out of the walls. It is strongly suggested to carry allof, or at least a majority of, the collector steel through the length of the wall, for a few reasons1) Ensures adequate embedment depth of the collection steel itself2) Ensures that that tension collection reinforcement will reach the compression zone of the wall(given that when the tension collector is engaged, it is only embeded into the tension zone of the wall)3) Given flexure-shear interaction in the wall,which is currently not captured in the analysis, themajority of the shear demands in the wall will be localized in the compression zone of the wall at oneedge of the wall. This requires a mechanism in which to "drag" the shear force back through thelength of the wall to be distributed to the shear friction dowels as well as the tension collector. Thecollection rebar continuing through the length of the wall could serve this purpose. (See tab"Comment #86 Figure" below)

01/25/18 We agree with the reasons presented for carrying the collector through the length of the wall at thetransfer diaphragms. However, to alleviate conjestion throughout the wall, please see Exhibit 86 forcalculation showing that using the reserved shear capacity of the wall through the providedembedment length is adequate to transfer the loads.

Exhibit 86

03/20/18 It is agreed that the reserve capacity of the shear wall horizontal bars can be used to deliver thecollector force back through the full length of the wall. However, see additional sketch on the"Comment #86 Figure" tab and the following comments, representing the example calculationprovided as part of Exhibit 86:

The collector will only be able to engage a certain of bars within it's zone of embedment (conceptuallyrepresented with the dashed lines) as shown in the sketch, which assumes 45deg angle ofengagement. The bars within this zone of embedment need to provide an effective Asfy greater thanthe tension force of the collector. The effective Asfy should represent the reserve capacity of thehorizontal bars in the wall that remains once seismic wall shear is considered (which per the exampleprovided appears to be about 207/330=62%). Also, the bars that cross within the zone of embedmentshould have their effective Asfy proportionally reduced if the length of engaged portion of horizontalbar is less than the development length (represented conceptually by the vertical black line).This embedment should be evaluated at all locations where tension collector steel is not extendedthrough the full length of the wall.

Regarding 2) & 3) above, the tension collectors extending into the compression zone of the wall islikely not critical below the transfer diaphragm, however please provide comment/evaluation of thisaspect for diaphragm collection/distribution at and above the 1st floor.

04/23/18 Please see the updated calculations in Exhibit 86.1.

For the above-grade diaphragms, there were some locations where reinforcement was required topass through the entire length of the wall (these checks had not been completed in our response of1/25/2018).

At the transfer diaphragms, Level 1 and below (data shown in Exhibit 86), to account for the potentialof reduced shear capacity due to wall net tension, the component of shear resistance provided by theconcrete was not included when computing the excess wall shear capacity available to collect the dragreinforcement (a conservative assumption since the whole wall will not be in tension). Only horizontalreinforcement in excess of the demand wall shear was used. Regarding the development of the wallshear steel at the end of the wall, it is argued that the entire length of bar can be used since thehorizontal shear steel laps with boundary zone ties and hoops with a neglible hook developmentlength, Ldh (7" for unconfined concrete, less for the confined boundary zones).

Exhibit 86.1

03/20/18 It is not clear that the updated calculations represent the description and figure referenced above. Theupdated calculation appears to be basing embedment length on a shear capacity (k/ft) rather thanhorizontal tensile capacity based upon the # of engaged available horizontal rebars.

06/07/18 We have followed Section 6.8 of the NEHRP Seismic Design Technical Brief #3 for Diaphragms, 2ndedition. Reserve capacity above the shear demand in the wall is used to collect the tension from thedrag reinforcement. Note that the cone pullout methodology was removed from the 1st edition of thisdocument. Exhibit 86.2 (and previously Exhibit 86.1) summarizes the required embedments. As a rule,we have extended half of the collector reinforcement through the entire length of the wall andcalculated embed lengths for the balance of the collector reinforcement. . A sample plan markup forLevel 9 is also shown.

Exhibit 86.2NEHRP

TechnicalBulletin #3

06/12/18

Given extension of1/2 of collectionsteel through fulllength of wall typ,Comment Resolved



(Section 5.4)

12/14/17 Some aspects of the floor layouts appear different between the figures presented in the calcs and thedrawings, such as:- Interior core opening layout along east side of core at P4 and P3-Extreme southeast corner opening in floor at P4 and P3-Opening directly south of the core is shown on the drawings but not in the calcs layouts on P4 throughP1-Opening shown northwest of core at P1 on the floor layouts that does not existing in the structuraldrawings

01/25/18 All openings should match the current drawings. Please see the Phase II Superstructure drawingssubmitted along with this comment response.

Phase II Permitdwgs

# Topic& Reference

Date ofComment



Date ofResolution

Resolution/Notes

14 of 19

03/20/18 Extreme southeast corner of P4 and P3 (per S2.P4) still shows an opening that does not appear to beconsidered in Figure 82-1 through 82-8.

Similarly, the opening directly south of the core is shown on the drawings but appears to still haveshear friction bars accounted over it's length at P4 through P2.

04/23/18 The southeast corner opening has been considered and does not affect the reinforcing required for thediaphragm. For the consideration of opening south of core, please see Exhibit 88 for updatedcalculation.

Exhibit 88




(Section 5.4)

12/14/17 Floors P4 through P2 appear to have a strip of specific, one-way slab slab extending beyond the northof the core. Please clarify how the strip is accounted for as part of the diaphragm design.

01/25/18 The strip is ignored in the calculation. Please see Exhibit 82. Exhibit 82

03/20/18 Please clarify how this portion of slab is ignored. The shear friction calcs along the north wall of thecore appear to utilize the full length of wall, including the width of this slab portion.

04/23/18 Please see Exhibit 88 for updated calculations that ignores the slab portion in question. Exhibit 88




(Section 5.4)

12/14/17 1) In relation to comment #89 and others related to ramping and openings in the grade-and-belowdiaphragms, please clarify the intent of the openings in the slab elements as shown on Pg. 12 and alsopresent in the model. Are these accounted for in the demands that have been used to design thesediaphragms?

2) Similarly, the Level P1 slab appears to include an additional E-W gap near Line G. Is this intentional?The gap will affect the load path distribution in this diaphragm

01/25/18 The openings are intentional and reflect the structural condition. For the typical level, the slab splits tothe north and south of the core interrupting diaphragm continuity. The large opening to the north ofthe core at Level P1 represents the location where the ramping parking slab descends below to P2 (seePhase II Permit Drawings)

Phase II Permitdwgs




(Section 5.4)

12/14/17 Please provide the calculations for the chord steel shown for the transfer diaphragms 01/25/18 Please see Exhibit 90 for calculation of chord steel at transfer diaphragms. Exhibit 90




(Section 5.4)

12/14/17 Specifically for the P1 diaprhagm:A majority of the southern portion of the slab is depressed over 4' per the structural drawings. Pleaseprovide the associated calcs and details related to the collector rebar, as shown on Pg.174, that travelthrough this step near Line G. Also provide the associated calcs and details for the step itself regardingtransfer of shear from one elevation to another.

02/22/18 Diaphragm shear is transferred by carrying all in-slab shear reinforcing through the step. At the southstep of Level P1, the forces from the collector is taken by the capacity of the columns, please seeExhibit 91 for calculation.

Exhibit 91

03/20/18 1) Column G/4 (which sees the collector to the east wall) appears to be the critical case. It is noticedthat the PMM DCR's are very close to 1.0 - is it possible to provide supplemental reinforcement in thiszone to protect the column from this induced flexure?

2) Similarly, at the same column, please provide the shear check based upon the same force as well. Arough check shows that this may exceed the column shear stress limits.

04/25/18 1) The loads have reduced and an updated calculation has been provided in Exhibit 91.1 showing thatthe columns have adequate capacity to resist the induced shear and moment.

2) See Exhibit 91.1 for shear check.

Exhibit 91.1

05/18/18 1) Please clarify what reduced the loads as shown in Exhibit 91.1, as these demands appearsubstantially reduced.

2) Please clarify how the existing shear and flexure in the column itself is resisted in this region - thecalcs appear to only account for the shear and flexure resulting from the diaphragm force at the step.Please clarify if all concurrent forces can be accomodated.

06/04/18 1. The P1 level was modeled differently in the final Perform Model to include the large opening off theNE corner of the core. As a result, P1 reduced while L1 and P2 forces increased. Please see Exhibit 91.2

2. The column forces were taken directly from the Perform model and combined accordingly. See thecolumn calculations in Exhibit 113.2.

Exhibit 91.2

06/12/18 1)a) Please provide the updated model that is referenced. Is this area in the at Lev 01 actually acomplete opening, or is it a ramped surface area?b) Please confirm that the increased loads at Level 1 and B2 have been included in the diaphragmdesign for those respective floors. Did this modify the designated diaphragm at these floors?

2) See Comment #113.2

06/15/18 1a) The current Perform model has been included in this response.1b) Confirmed. This change was included in results presented earlier in Exhibit 81. For clarity, theupdated design for Level 1 and Level P2 has been reproduced in Exhibit 91.3.

CurrentPerformmodels

(9J_03g and9J_03h)

Exhibit 91.3




(Section 5.4)

12/14/17 General transfer diaphragm comment:Some of the rebar (for example, the N-S collector out of the southeast corner of the core as shown onPg. 174) does not match the reinforcement shown on the set of structural drawings currently provided- please clarify, or provide the updated drawings.

01/25/18 Please see response to comment #87. Phase II Permitdwgs




(Section 5.4)

12/14/17 Specifically for the P1 diaphragm:On Pg. 174, (2) #11 bars are shown (E-W) east of the core between lines D and E as chordreinforcement. Is this portion of the slab part of a ramp? If so, does this rebar truly get engaged aschord bars?

01/25/18 This portion of the slab is part of the ramp. The reinforcement is placed at the edge of the considereddiaphragm depth at this portion such that it can be engaged as chord bars.




(Section 5.4)

12/14/17 Specifically for the P1 diaphragm:On Pg. 175, for the shear friction calculation for demand at the north wall, there is a length of 18' ofshear friction provided to transfer 503k of shear. Please justify this amount of shear transferring intothe interior slab of the core. If this shear is transferred through shear friction, please includeassociated calculations that confirm that the small segment of slab in the northwest corner of the corehas the capacity to resist this shear. Also, does any of this shear then remain in the one-way slab thatruns through the middle of the core? Similarly, see comment #82

01/25/18 Please see response to comment #82 - it is not intended to use the inside of the core for sheartransfer.

Exhibit 82




(Section 5.4)

12/14/17 General transfer diaphragm comment:Confirm that the diaphragm itself has adequate shear capacity directly adjacent to the collectors to"absorb" the shear that the collectors are delivering into the diaphragm

01/25/18 In-slab shear calculation for each transfer level has shown that the diaphragm has adequate shearcapacity directly adjacent to collectors to "absorb" the shear delivering into the diaphragm. Note thatthe calculation uses the entire length and shear load at the simplified beam model of the diaphragm.Since the shear across the collectors is uniform across the length, the provided shear reinforcing withinthe diaphragm is adequate. 03/20/18 Comment Resolved



(Section 5.4)

12/14/17 Specifically for the L1 Diaphragm:The diaphragm shear at this level is essentially treated as a flat diaphragm - please include details andcalcs that account for the various elevations at this level, including design of the "stub" walls that spanbetween the elevations.

01/25/18 Diaphragm shear is transferred by carrying all in-slab shear reinforcing through the step. Forcalculation of collector through step, please see Exhibit 96.

Exhibit 96

# Topic& Reference

Date ofComment



Date ofResolution

Resolution/Notes

15 of 19

03/20/18 1) On Figures 96-1 and 96-2 (of Exhibit 96), some locations are identified with additional #11 bars "ateach face for beams"- please clarify the detail that these relate to, their function, and relatedcalculations

2) Although continuous Z-bars are provided to maintain continuous reinforcement to transfer shearthrough steps, please provide calcs to confirm that the eccentric demands require no other additionalreinforcement at the steps.

3) Please clarify what location the calcs on Figure 96-3 relate to.

04/25/18 1) The face reinforcing is used as a secondary load path to transfer the in-slab shear through stepbeam with the axial capacity.2) See Exhibit 96.1 for calculation.3) The calculation is related to load transfer through step at the collector beam on grid D east of core.

Exhibit 96.1




(Section 5.4)

12/14/17 Specifically for the L1 Diaphragm:The structural drawings indicate a ramp at the northwest edge of the core at this level. They alsoindicate an adjacent opening to the west near Gridline C, creating only a small zone of diaphragm leftat the L1 level in this zone. Please clarify the load path in this zone and provide calcs showing the theremaining portion of diaphragm is adequate. Please also confirm that the diaphragm has adequatelength to receive the loads from the adjacent collector along Line 3 as well as the one along Line D.

01/25/18 Please note that for the E-W direction loading, for the calculation of the collector at the North core,length to the west (left) is not included, although collector is still provided. A complete load path isprovided by the shear friction of the north core + collector to the east (right), while the collector to thewest (left) is an alternative load path.

03/20/18 For the E-W direction loading, although the intended load path is through shear friction along thenorth wall (and the western collector is just an alternative load path), the ramp opening breaks theload path between the north wall and the portion of diaphragm west of the core. Ensure that thedesign as currently provided does not depend on this load path.

04/25/18 The design does not depend on this load path. The in-slab shear calculation for Zone 1 is 71'-0" inlength and omits the openings northwest of core. Exhibit 97 provides an update of the sheartransferred through each zone of the diaphragm.

Exhibit 97




(Section 5.4)

12/14/17 Specifically for the L1 Diaphragm:There appears to be an opening north of the column at Grid B/3. The current collector layout shows aN-S collector continuing through this opening. Has the actual length of the collector already beenaccounted for and this is just a graphical issue?

01/25/18 This is a graphical issue. The actual length has been taken into account and the collector terminates atthe opening.




(Section 5.4)

12/14/17 Specifically for the L1 Diaphragm:Given the ramp opening directly northwest of the core, please justify the shear friction load path forwhen load coming out of the core into the the diaphragm is traveling towards the north (and thereforetowards this opening). PLease confirm that the segment of slab directly to the west of the core has theshear capacity to transfer the shear including the opening.

Since uniform shear has been assumed, the in-slab shear calculation has shown that the slab directlyto the west of the core has the shear capacity to transfer the shear.Exhibit 82 page 18 for Zone 1 in-slab shear calculation showing the adequacy of the diaphragm.

Exhibit 82




(Section 5.4)

12/14/17 General Diaphragm Comment:Please provide a sample calculation of the "In-Slab Shear Design" at the bottom of the typical transferdiaphragm calc sheets. When these results indicate no additional steel is required, is this accountingfor the gravity rebar already present in the slab? If so, what percentage of the gravity steel is assumedeffective?

01/25/18 Please see Exhibit 90 for percentage of gravity rebar used in calculation of in-slab shear. When noadditional steel is required per the calculation, it indicates that concrete strength alone is adequate.Please see Exhibit 100 for sample calculation of the "In-Slab Shear Design".

Exhibits 90,100

03/20/18 Please confirm that at Level 1, where gravity loading is different and typically higher than the levelsbelow, the additional gravity demands were considered when determining the percentage of rebaravailable for in-plane shear resistance.

04/23/18 The reinforcement required for the design of in-plane shear resistance at Level 1 was conservativelyadded to the reinforcement required for gravity.



Typical DiaphragmDesign

(Section 5.4.2)

12/14/17 Given non-uniform width of the diaphragm in both directions, please uniform loading to instead beproportional to the width of the diaphragm at that location (assuming equal applied load massingalong the floorplate - if this is not the case, please account for the uneven applied mass as well).

01/15/18 See Exhibit 45.1 for a non-uniform diaphragm loading for code-level force. Similar distribution will beused for MCE level loads.

Exhibit 45.1




(Section 5.4.2)

12/14/17 Please confirm that when in the description of lateral loading on the diaphragm, "maximum" loadingimplies the absolute maximum of max and min values

01/08/18 Confirmed. Also, see response to comment #103 which includes revised diaphragm loads.




(Section 5.4.2)

12/14/17 While it is agreed that the acceleration*mass of the core should not contribute to the diaphragmdemand, using a straight ratio of weight may be reducing the diaphragm demands by too great of avalue. In order to ensure that the core does not contribute, it is recommended to utilize accelerationsout of the nonlinear analysis, and multiply this by the mass of the story in question minus the mass ofthe core at that level. Along with this, please provide the mass breakdown at each floor (slab vs. col vs.core vs. superimposed)

01/08/18 A mass breakdown at each floor is provided in EXHIBIT 103a per your request. Accelerations areprovided in Exhibit 103b and 103c.

Exhibit 103

03/20/18 1) The additional constraints/components as shown on 103b are not seen in the current providedPerform model - please clarify - was this only a parametric study?

2) It appears that new diaphragm demands were calculated in conjunction with this. The table inExhibit 45.1 shows MCE diaphragm forces that are different, and typically larger than those that wereprovided on Pg. 183 (Figure #144) of the 11/23 submission. However, no updated typical diaphragmcalculations are found - please clarify.

04/23/18 1) The wrong version of Exhibit 103 was inadvertently sent (this was part of a parametric study). Pleasesee the updated Exhibit 103.1, the intended version.

2) Please see Exhibit 103.2 for typical diaphragm calculation with updated loads

Exhibit 103.1

Exhibit 103.2




(Section 5.4.2)

12/14/17 Please clarify how the "B" values (1.17 for concrete and 1.0 for rebar) were determined. 02/22/18 Please see Exhibit 80 Exhibit 80




(Section 5.4.2)

12/14/17 Please refer to Comment #45 regarding the shear friction along the west wall. Please provide a clearload path on this side of the core that can deliver the shear through strut and tie action to the westernwall face for shear friction transfer.

Pg. 190 appears to have a note related to this, indicatng that the collection force is only resolvedthrough collector reinforcemnt due to the openings at the slab-wall interface, however shear frictionbars are still calculated and shown on this diagram, so the intent is not completely clear.

01/15/18 The intent is to not rely on shear friction bars along the west wall due to the large openings along thewall. See Exhibit 45.1 for updated calculations. The same design intent will be used for MCE leveldiaphragm forces.

Exhibit 45.1


# Topic& Reference

Date ofComment



Date ofResolution

Resolution/Notes

16 of 19



(Section 5.4.2)

12/14/17 The diaphragm design for L4 and L9-13 have been provided. Will the remaining diaphragms also beprovided? Please clarify if L4 and L9-13 are intended to envelope the design of other typicaldiaphragms.

01/08/18 These diaphragms were provided as the sample calculations to show methodology, not as anenvelope. The other diaphragms have been designed as well; calculations can be submitted uponrequest.

03/20/18 Please refer to comment #103…it is not clear that updated MCE Calculations have been provided.Please provide all MCE diaphragm calculations

04/23/18 Please see Exhibit 103.2 for typical diaphragm calculation with updated loads Exhibit 103.2

05/18/18 Please provide the set of calculations that envelopes the entirety of the typical diaphragms beyond L9-13

06/07/18 Please see Exhibit 45.4 for the comprehensive calculations. Exhibit 45.4




(Section 5.4.2)

12/14/17 Pg. 186 and Pg. 191 include a few instances of a 1.5x amplifier for demands on the southern wall -please clarify what this amplification represents.

01/10/18 These were typos from a previous version of the spreadsheet that were overlooked. We haveconfirmed that the formulas used to prepare the submitted calcs did not have this amplifier.




(Section 5.4.2)

12/14/17 For Level 4 per Figure #148:Please confirm that no supplementary chord reinforcement is required at the west or east edge of theopening at the southern face of the slab

01/25/18 Confirmed. The depth of diaphragm used when calculating chord reinforcing is from gridline H.5 togridline B, which is shallower than the full depth.



Knuckle Columns(Section 5.4.2)

12/14/17 While the general approach as shown is agreed, please provide the specific calculations related to theload path as shown, and the associated additional reinforcement if necessary.As part of these calculations, please include the assumed width of the struts developed in the slab,along with checks for ACI requirements for confinement.

01/10/18 Please see Exhibit 109 for calculations. Exhibit 109

03/20/18 1) General comment: Where slab shear is evaluated, 2root(f'c) is accounted for to resist slab shearsresulting from the sloping column demands. These shears overlap with areas that resist seismicdiaphragm shears that also utilize 2root(f'c) to resist demands. Is the concrete shear capacity beingdouble-counted in these situations?

2) General comment: Please confirm that where addiitonal "collector" steel for resistance of thesloping columns is required, these bars are provided in addition to collector steel provided to resistseismic diaphragm collection demands.

3) General Comment: Similar to 2) above, where shear friction steel was required to transfer thesloping column demands to the shear walls, please confirm that this shear friction steel was in additionto that provided to resist seismic shear collection demands.

4) Where column thrust compression demands are resisted by a pure compression strut (such as thatshown at Level 2 for Column 6/F), please clarify how the compressive capacity of the slab wasevaluated. Given that it is acting in a similar manner to a compression collector strut at the face of ashear wall, were slab confinement requirements checked at these locations?

5) For Column 5/C @ Level 2, the required Tie 1 As=11.67in^2, however the drawings currently onlyshow 10#9 at this location. Please clarify

6) Where additional diaphragm shear steel is required (such as that for Column 5/C @ Level 2), it is notclear where this is specified on the provided set of drawings.

04/25/18 1) It is agreed that the calculation shall be combined. See Exhibit 109.1 for sample calculationcombining the diaphragm and knuckle demand at column 6/E.2) Confirmed.3) Confirmed.4) See Exhibit 109.1 for sample calculation for the compressive stress check at compression strutshowing that confinement are not required.5) The drawing will be revised to (12) #9 at this location to provide 12in.^2 of reinforcing area.6) Diaphragm steel is shown on the R sheets.

Exhibit 109.1

05/18/18 1) For the Column 6/E calc provided in Exhibit 109.1, the slab shear to be added to the column thrustshear is noted as 631k in one text box, but is noted as 581k when added to the 105k coming from thecolumn thrust. Please clarify which value is correct. Also, this check is only provided for Column 6/E -was additional shear reinforcement required at other locations?

2) Closed

3) Closed

4) Justify the use of 8*tslab as the effective width of the slab that resists compression. Is there areason this value is utilzied in lieu of a typical strut width from a strut and tie approach?

5) Closed

6) Referencing the additional bars (#4 @ 18" O.C.) for Level 4 Column 6/E (see 1)), it is not clear wherethese bars are called out on S2.04R - please clarify.

06/07/18 1) The 581k value used in the calculation is correct. Please see Exhibit 109.2 for calculations for theother knuckle column transfers.

4) T-beam effect is considered for the use of 8*tslab. Ignoring the 8*tslab component, the arearesisting the strut is 8.5"*24" = 204 in.^2, which gives a compressive stress of 188k/204in.^2 = 0.92ksi= 0.15f'c. Therefore, without the consideration of T-beam/8*tslab, the result would still be that noconfinement is required.

6) Please see the attached Sheet S2.04R - note that #4 @ 16" are called out instead of #4 @ 18" (tomatch spacing of other bottom steel).

Exhibit 109.2Sheet S2.04R

06/12/18 1) For Level 2 Column 6/F, the shear demand appears to only consider the thrust force not incombination with the diaphragm force. However, supplementary rebar does appear to be provided onS2.02R in the slab zone that would transfer this shear - please clarify if diaphragm shear was combinedwith thrust demand similar to the other knuckle column locations at this Column 6/F.

4) Closed

6) Similar to the 05/18 comment, updated calcs show additional slab bars are required at Level 2 Col5/C and Level 19 Col 6/E, but this additional rebar can not be found in the currently provided sheets.Please confirm that this additional rebar has been specified on the appropriate sheets (and provideupdated set of drawings)

06/15/18 1) Please see Exhibit 109.3 for the updated calculation for Column 6/F at Level 2 including both theknuckle column and seismic shear. The calc shows #6 @ 12" required, which is the value shown on thecurrent drawings (also included in the Exhibit for reference)

6) This reinforcement has been added. Please see the updated drawings, which are included in Exhibit109.3

Exhibit 109.3




12/14/17 Please confirm that the axial demands shown on Pg. 194 include the contribution of both seismicoutriggering as well as vertical acceleration

01/08/18 Confirmed, axial demands shown on Pg. 194 are taken from the governing axial column load on Pg.204 which includes the contribution of both seismic outriggering as well as vertical acceleration.




12/14/17 Please also include the evaulation of the knuckle column shear and flexural demands, and theirresolutions at the extreme ends of the knuckle column.

01/25/18 The chosen load path shown in p. 1 of Exhibit 109 (eccentric axial force equilibrated by a slab couple)does not induce column shear or flexural demands in the knuckle column.

Exhibit 109

03/20/18 To clarify, the comment is asking specifically about the shear and flexure that are resisted in thecolumns due to framing (similar to the shears and flexure that the non-sloped columns also see).Please justify that the detailing at the top and bottoms of the sloping portions of the columns, canaccomodate the transition in column size and the associated column demands. Shear reinforcementand flexural reinforcement are designed and placed based on the lower column,

(Also see comment #31)

04/24/18 Please see Exhibit 111. Per the response to Comment #31, the gravity moments and shears generatedat the slab interface are conservatively resisted by the column cross-section below the slab (i.e., onlythe column below is modeled in Ram Concept, not the above column). The design and detailing of studrails and reinforcement are based on the lower column.

Exhibit 111

05/18/18 Previous comment was referencing framing from seismic demands. Please clarify the demands in thistransfer column (which is modeled as a shell in the NL model) and clarify how the shears and flexure inthis component due to seismic+gravity are resisting both within the transfer column itself and at it'sends. As part of this, please provide the shear and flexure demands recorded from the NL analysis

06/07/18 Please see Exhibit 113.2 for the column shear and flexure calculations. Knuckle column forces fromPerform are included here.

Exhibit 113.2

05/18/18 1) For flexure, see comment #113. Please provide PMM design of these columns based upon thedemands from the MCEr analysis.

2) As noted in the 05/18 comment above, it is expected that these columns, particularly the largerones, will attract some degree of seismic shear and flexure in the model. Beyond confirmation of thecolumn's capacity to resist these demands, please also confirm that the slab connections at each endof the column have the capacity to resist these demands (see Comment #31 and associated figure)

06/15/18 1) Please see response to comment 113.

2) The column forces have been designed for as shown in Exhibit 113.2. Exhibit 111.1 shows theresulting demands for the column at C/5 using a RISA model of the transfer column with the assumedload path and boundary conditions. The column is much stiffer than the slab and very little bending isimparted to the slabs.

111.1

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06/26/18 1) See further discussion of #113. Particlarly given the extended lengths of these knuckle columns, itseems pertinent to ensure that their designs can accommodate the lateral demands they may attract(due to lateral demands, not just stepping or sloping).

2) The image shown in 111.1 only applies the axial force in the column. This comment is requestingthe that shear and flexure demands that these columns may attract (due to lateral demands, not juststepping/sloping) can be developed at the top and bottom of the columns where portions of thecolumns land against slab.

07/27/18 1) The knuckle columns have been upgraded to resist the imposed MCE moments from Perform, aboveand beyond the methodology used for the typical columns described in Comment #113. The load pathfor the eccentricity of axial (both MCE and code-level) load combinations is resisted by a slab couple asdescribed above. Additionally, the knuckle portion of the column and the columns directly above andbelow the knuckle have been designed for the MCE PMM combinations. See Exhibit 111.2 for a loadsummary and sample PMM calculations for the column at C/5. Note that the bias factor was used inthe moment calculations to remove some of the conservatism.

2) Design for MCE shear has been performed for all columns as described in Exhibit 113.2.

111.2



Column Design(Section 5.5)

12/14/17 Pg. 205 has a column labeled " Pu Gravity" - however it appears that these values match those on Pg.204 from the factored MCE load combination. Please confirm that these values are indeed the MCEfactored load combos.

01/08/18 Confirmed, "Pu Gravity" is a column header mistake. The values used in the column design are indeedthe MCE factored load combos provided on Pg. 204 Figure 163.



Column Design(Section 5.5)

12/14/17 1) Please also provide the related shear and PMM design of the columns. Although Pg. 206 includes aφMn/Mu ratio, it is unclear what demands were used or how this CDR was determined.

2) Please also include an additional table that includes the column Pu/f'cAg ratios from the factoredMCE load combinations

01/24/18 1) Column shear induced by lateral loads will be checked per ACI 318-14 Section 18.14 with loads fromthe updated lateral analysis. Calculations provided on pg. 206 show shear and PMM design of thecolumns due to the governing gravity load combinations. The moment demands were approximatedfrom slab geometry, and the CDR was determined through spColumn runs.

2) Please see Exhibit 113 for the Pu/f'cAg ratios from the factored MCE load combinations

Exhibit 113

03/20/18 1) Please provide the calculations for column resistance of seismic PMM and shear

2) It appears as though a decent number of columns are close to or exceed axial ratios of 0.4Agf'c.Although these are not special moment frame columns, LATBSDC 2017 Section A.4 notes that once thislevel of axial load is reached, deformation capacity of the columns is reduced. If the column PMMratios to be provided per 1) indicates non-negligible amounts of deformation capacity are required atthe columns, the axial ratios should be reduced.

04/25/18 1) The final PMM and shear design and checks are currently in process. Please see Exhibit 113.1 for asummray of the design methodology. The intent is to discuss this with you before finalizing thenumbers.

2) We contend that since these columns are not designed as moment columns, this provision shouldnot apply (not to mention that Basis of Design reference document (TBI) does not require this). We arenot relying on these columns as part of the lateral force resisting system, only as gravity columnsdesigned to meet code load demands and MCE demands as a force-controlled element.

113.1

05/18/18 1)a) Regarding moment demands: What is the difference between "Typical Condition" and "SelectedCondition" designations- why are they evaluated differently?

b) Regarding moment demands "Typical Conditions": ACI 18.14.3.3 provides requirments for rebardetailing (18.7.4, 18.7.5) and a capacity-based shear demand (18.7.6), but does not providerecommendations to determine flexural demands in columns based upon Mpr of the adjacent slab.PEER TBI 6.4. notes that the gravity system should be included and evaluated directly in the mainanalysis model as either deformation or force-controlled actions, using the same acceptance criteria asthe lateral force resisting system. It is noted that secondary models (with similar imposeddeformations) can also be used, but since the columns are already included in the NL model, thiswould not seem necessary. Similarly, since outrigger beams with hinges are already included in the NLmodel, it is not clear why all column seismic demands are not being evaluated directly from theanalysis (as referenced for "Selected Locations".

c) Regarding shear demands: Agreed that it would be acceptable to determine shear demand in thecolumns based upon their expected flexural strength. However, please note that the referencedsection 18.4.3.3 also requires that Ve not be less than the factored shear calculated by the analysis ofthe structure.

d) Has including PMM hinges in the columns and checking as deformation controlled actions beenconsidered?

2) While these specific requirements come from a separate document, the referenced research thatthe section is based upon would be applicable to all projects. This criteria would seem relevant if theresults from #1 above revealed that columns were expected to hinge and undergo non-negligibledeformation/ductility demands, as the deformation capacity is of course substantially reduced underhigh axial loads. If deformation/ductility requirements for the columns are low, this would be lessrelevant. However, it would also be recommended to at least maintain ACI Section 18.7.5.2(f) detailingfor high-strength concrete/high axial loads.

06/08/18 1) For MCE, instead of checking moments directly, we will follow 18.14.3.3 where induced momentsare not checked and columns are designed and detailed to meet 18.7.4, 18.7.5, and 18.7.6.1b) Shear at column joint has been calculated per ACI 18.7.6.1.1 and in no case was the calculatedshear taken less than the shear demand from PERFORM analysis - see Exhibit 113.2 for tabulatedvalues.1c) (Note the referenced section should be 18.14.3.3, not 18.4.3.3). We have checked this as stated in1a and 1b.1d) We decided early on to proceed as we have done in past projects and treat the columns as force-controlled.

2) As discussed above, the columns have been ductilely detailed according to the provisions of 18.7.4,18.7.5, and 18.7.6 assuming that yielding might occur.

Exhibit 113.2

06/12/18 1)a) As noted in the commentary of PEER TBI 6.8.1, "All elements of the primary lateral force resistingsystem and the gravity force-resisting system are to be checked for actions resulting from combinedgravity loads and MCEr evaluation earthquake loads", without an option to not evaluate per ACI18.14.3.3. Therefore, please provide the seismic axial+flexure (PMM) column evaluations utilizing theflexure obtained from the MCE analysis. While this may not control for many columns, it is expectedthat some columns particularly near the base may be controlled by the flexure demands from theMCEr analysis.

b) As noted in Exhibit 113.2, there are two locations at Lev 01 (Columns 3-C and 4-G) where shear atLoc 2 are inadequate when checked with Vs alone. For these two locations, concrete capacity appearsto be added back in, resulting in DCR's that are still close to acceptance (0.99 and 1.02). Please justifythe use of concrete shear capacity at these two column locations at Loc 2.

c) Closedd) Closed

2) Closed

06/15/18 1a) We contend that Perform moments need not be checked as ACI is the governing code, not TBI. Thisis consistent with what we have done on previous projects.

1b) ACI 318-14 Sec. 18.7.6.2 was checked at both locations to verify Vc could be used to calculateshear capacity of the column. See Exhibit 113.3 for calculations.

Exhibit 113.3

06/26/18 1a) It was noted in both the BOD and in Comment #8 response that columns would be evaluated asforce-controlled for shear, and deformation controlled for axial+flexure (per note 3 of TBI Table E-1).The columns are included in the nonlinear model but have been modeled as fixed members (notpinned) with no hinges. It is not clear how the deformation-controlled acceptance criteria hastherefore been confirmed. For this reason, as noted above, the PMM results (based upon seismicdemands) have been requested in the previous entries of this comment.

1b) Closed

07/26/18 The intention in labeling column axial-bending as deformation-controlled behavior was to ductilelydetail the columns per ACI (see 6/8/2018 response). Missing in the Basis of Design was an explanationof how this would be done. This update to Section 5.3 has been included in Exhibit 113.4.

Per our phone discussion, to demonstrate that the amount of shear being carried by the columnsrelative to the walls is small, please see the diagrams in Exhibit 113.4, reproduced from the MCEpackage dated 12/11/2017. The four plots show that the core takes the vast majority of the totalbuilding shear.

Exhibit 113.4

08/08/18 In the context of this project, the ductile detailing as noted will suffice to satisfy the requirement oftreating the gravity column axial-flexure behavior as deformation-controlled.

A few additional notes regarding the column shear:Although the diagrams in Exhibit 113.4 do show that for a majority of the height of the buiding, thecore resists almost the entire story shear, it also appears that at the lower levels of the building(~below L04) a non-negligible amount of the story shear is resisted outside of the core (and thereforemust be resisted by the columns).

Per Exhibit 113.2, it appears that column shear was designed from the maximum of either the capacitybased (ACI) shear, or the shear determined straight from the Perform model utilizing linear elements(no hinges). Therefore the columns themselves appear to have adequate shear strength. However, itis not clear if all columns will truly remain elastic in order to attract as much shear as they report in themodel, where the columns are modeled elastically. If the columns yield in flexure, presumably allshear in that column from the analysis greater than Vp would be resisted by the core wall.

For example, looking in the Y direction at L03, the total sum of column Vp (from Pg. 18 of Exhibit 113.2)is about 1418k less than the total sum of column Vu (from Pg. 19 of Exhibit 113.2). These total sumsmay not occur simultaneously, but it does indicate that some of the lower levels of the structure mayhave more shear in the columns than the columns can attract/resist after yielding, meaning someresidual additional shear may need to be resisted by the core wall.

At the levels below L04, where core and total building shear appear to have the greatest divergences,please confirm that the columns have adequate strength to resist the demands from the analysis, orshow the shear wall can accomodate the additional residual shear demands.

08/20/18 Please see Exhibit 113.5 for the following discussion.

While it is true that some load could be shed from the columns to the walls at Levels 1 thru 4, buildingshear not resisted by the core below Level 1 is resisted primarily by the basement walls (see pages 2 - 4of Exhibit). Note also that core shear capacity was not reduced below Level 1 even though the analysisshows that demand decreases.

That said, we did further explore the reallocation of column shear to the walls. The second part ofExhibit 113.5 demonstrates that the core has adequate capacity to resist excess shear shed by anycolumns that experience flexural yielding. The amount of additional shear shed to the core wasdetermined by subtracting the ACI shear demand from the MCE demand. This is considerableconservatism built into this study: not all of the columns that are assumed to shed shear actually reachtheir yield moments; column shears have not been monitored on a time step basis; maximum columnshears will likely not occur at the same time as maximum wall shears.

Exhibit 113.5



NL Model 12/14/17 Please provide a sample calculation of how the distributed masses at individual nodes at the L1 slabwere determined

01/08/18 A sample calculation is provided in Exhibit 114. Exhibit 114



NL Model 12/14/17 It appears that nodal loads are applied to all nodes for the "Total Live (>100 psf Category)" even onfloors that do not have any loading in this category. Although it appears that in general these loads aresmall, please confirm that the import process for the gravity point loads is accurate.

01/08/18 If a floor has no load in this category then there should be no associated load. However, we believemost floors have some loading in this category, albeit a relatively small amount, e.g. isolated storageor mechanical load. There is a bit of a "butterfly effect" where a tiny amount of load shows updistantly from the loaded region. For the purpose of matching resultants precisely from the ETABSmodel to the Perform model, these loads have not been altered. In summary, the import process forthe gravity load is accurate. 03/20/18 Comment Resolved

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Submittal (2/26/2018): MCE Addendum 1: Steel Coupling Beams

MCE Submittal Coupling Beams Note to Reviewer: The design team and the contractor have elected to implement structural steelcoupling beams for the typical 26" deep beams from Level 3 to Level 25. Please see MCE Addendum 1for a summary of the methodology and sensitivity studies for selected performance parameters.

MCEAddendum 1

116 Addendum 1 - SteelCoupling Beam Update(02/26/17)

Steel Coupling BeamCalcs

(Pg. 16)

03/20/18 1) Please provide a sample hand calc that walks through all of the calcs that are performed in thistable (through Pages 16-19)

2) Was embedment length calculated using expected strength as specified in Motther (2013) Section3.1.5?

04/20/18 1) Please see Exhibit 116.

2) Yes.

Exhibit 116

05/18/18 1) Detail 14/S4.13 shows the interior vertical bars that run across the thickness of the wall (at theedges of the boundary zone) discontinuing at the embedded steel beam section (see B of detail 14).Are these vertical bars that are discontinued utilized for any design purpose other than vert. bars atthe ends of the confinement ties? Does their discontinuation impact any other aspects of the design?

2) Closed

3) Please provide calculations that determined the design of the threaded rods/plates through thesteel section, per Motter Section 2.6.2.2.

05/29/18 1) These bars were used in the original wall PMM calculation, but PMM capacity for these walls istypically much higher than demand. Looking at p. 61 of the DE/SLE/Wind package--a summary of thePMM results--the lowest CDR for Levels 2 thru 25 is 1.958. By inspection, omitting the two (or four)bars interrupted by the couple beams from the cross-section will not reduce section capacity belowdemand.

3) Per details 14 and 19/S4.13, tie rods are provided at each interrupted cross-tie. Exhibit 116.1 showsthat this provides an equivalent or greater confinement in all cases.

Exhibit 116.1




(Pg. 16)

03/20/18 1) It does not appear that auxiliary transfer bars and bearing plates are to be provided. Per Motter(2013), these are not required. However, Pg. 19 appears to show a calc related to face bearing platesand vertical transfer bars - please clarify.

2) Similarly, Motter (2013) notes that for non-prescriptive designs, the level of wall boundarytransverse reinforcement is used as a basis for categorizing the coupling beam force-deformationbehavior. However, Pg. 19 appears to be calculating boundary zone reinforcement, noting "IncreaseReinf". Please clarify how the boundary zones affected by the steel coupling beams were evaluated.

04/04/18 1) The calculations pertaining to auxiliarly transfer bars and bearing plates are part of a morecomprehensive spreadsheet. This includes calculations for code prescriptive requirements including:i) A vertical boundary reinforcing checkii) A calc on face bearing plate sizingiii) A calc on vertical transfer bars.The latter (2) calcs can be ignored. Consider these for informational purposes only. Our intent is tofollow Motter section 2.6.3. such that auxiliary transfer bars and bearing plates (as required by 2010AISC Seismic provisions) are not required.

The code prescriptive boundary reinforcing check can also be ignored to the extent that the codeminimum vertical boundary reinforcing is not required by Motter. Vertical reinforcement in theboundary zone was not increased as a result of the code check evaluation in the spreadsheet.Consider this also for informational purposes only. However, as you have indicated, the amount ofvertical reinforcement does come into play in the classification of the steel coupling beam.




(Pg. 18)

03/20/18 Please note that on Pg. 18, the bottom right hand corner references a 45" embedment length for theW18x130 and W18x158 beams. On Sheet S4.13, these beams have a 41" embedment length. Pleaseclarify/update

04/04/18 The embedment length on S4.13 is incorrect and will be revised from 3'-5" to 3'-9".

05/18/18 Confirmed that embedment length is correct. However, please note that detail 14/S4.13 appears toshow the "start" of the embed length at the edge of the wall. Per AISC 341 Section H4.5b(3), theembedment length shall be considered to begin inside the first layer of confining reinforcement in thewll boundary member.

05/23/18 This has been accounted for; the specified embedment length includes an increase to account for thespalled cover concrete (see "c" values on p. 7 of Exhibit 116).

Exhibit 116




(Pg. 21)

03/20/18 It is noted that the beams are modeled per Motter (2013) as a Category III beam as discussed inSection 3 of the paper.

Was this designation assigned from calculations, or was it conservatively assigned based upon the factit is utilizes the "weakest" backbone per the factors shown in Table B.3 of the paper?

If conservatively assigned, and if the true design as detailed would place the beam in a "higher"modeling category, please confirm whether the stronger global coupling that would result from thishas been investigated.

04/04/18 Beam chord rotations are not known until after the time history analyses have been run. As such, theprocess is by definition iterative in nature. We assumed maximum chord rotations of 0.06. Per MotterTable 3.1, with this assumption, if a wall is lightly reinforced (with As x fye / Cb < 0.5) with 100%embedment, then it is an SRC4 type. Almost all walls are lightly reinforced so most of the steel beamshave been modeled as SRC4. However, the walls at Lev 3, 4 and 5 slip into an SRC3 classification withAs x fye / Cb = 0.55 and have been modeled with type SRC3 backbone curve.

Analysis results indicate that the vast majority of steel beams see max chord rotations less than 0.03.Technically, we could shorten the embedment length to 80% to have the analysis results fullyconsistent with Motter categorization but this is not a better design.




(Pg. 21)

03/20/18 It is noted on Pg. 21 that the steel CB's are modeled as SRC4 type. However, in the table at the bottomof Pg. 19, there appear to be some CB's assigned to type SRC3, which would place the beam inCategory II instead of III. Please clarify.

04/04/18 Some beams have indeed been modeled as type SRC3. See response to comment 119.


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(Pg. 24)

03/20/18 The sample Perform input on this page does not appear to the match the beam type (Category III)specified. Please update with example calculations based upon a sample beam directly from thecurrent nonlinear model.

04/04/18 For updated calculations, please see Exhibit 121. Exhibit 121




03/20/18 Please confirm that the wall demand limitations, as discussed in Motter (2013) Section 3.3.1, are met. 04/04/18 Confirmed. See exhibit 122. Exhibit 122



BOD Ver 4.0 (SteelCoupling Beam Update)

Pg. 23

03/20/18 1) Please clarify how the flexural stiffnes modifier at both DE, SLE, and MCE (0.07*l/h*Eitrans) wasdetermined.

2) Please clarify if, as described in Motter (2014) Section 2.4.1, effective stiffness values of the SRC'swere reduced by 20% when checking lateral drift.

3) Please provide justification for the use of the same effective stiffness multiplier for the SRC's at bothDE and SLE. While this is recommended for concrete coupling beams, it is not clear that the samejustification would hold true for the steel coupling beams.

04/04/18 1) The 0.06 x (L / h) x E x Itrans calculation was performed via a cracked section calculation consideringthe embedded steel shape plus any nominal additional longitudinal reinforcement (for further detailssee response to comment 116).2) We intentionally did not apply the 20% reduction on effective stiffness. In the vein of modelingactual response, we believe this to be an inappropriate "venue" for adding conservatism. This is ourposition as coauthors of the Motter paper. We will note that this value was discovered internally afterpublication of the finalized paper.3) The basis of design is incorrect. SLE effective bending stiffness modifiers for steel link beams havenow and always been taken as 1.5 times larger than MCE (and DBE) per Motter C3.1.4.

05/18/18 1) Closed

2) Per Motter Section C2.4.1, the 20% effective stiffness reduction when checking lateral drift limitsreflects uncertainty in the measured stiffness values, not a conservatism in evaluation. It would berecommended to take one of the worst-case time histories for drift (e.g. "2-2 Iran Tabas") tounderstand the relative impact of when this reduction in CB stiffness is utilized to understand if anymeaningful impact is missed.

3) Closed

05/29/18 2) We maintain our stance described above to model actual properties. But to your point, since thisstiffness reduction applies to drifts and MCE drifts are substantially below limits, limits would be metby inspection.


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COMMENT #6 FIGURE

COMMENT #31 FIGURE

Comment #84 Figure

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9TH & John - Geotechnical Peer Review Comment Log9/19/2018

Reviewers: Geotechnical Engineer:Marshall Lew GeoEngineers

Documents Received:1) Draft Memorandum - 9th & John Apartments - Site Specific Ground Motion Procedures, dated 07/12/172) Report on the Microtremors Array Measurements at 9th and John, Seattle, WA, by Oyo Corporation, Undated, received by SPRP on 7/21/173) Revised Geotechnical Master Use Permit Report, dated 05/22/174) Received 08/23/17 - Memorandum on Ninth & John Apartments - Site Specific MCER and SLE Response Spectra, dated 08/21/175) Received 08/23/17 - Comment Log for Block 21 Project by Maffei Structural Engineering, dated 03/20/17

6) Received 08/23/17 - Excel spreadsheet with MCE-R 5% damped Spectral Accelerations7) Received 08/31/17 - e-mail with attachments regarding "9J Proposed CMS Conditioning Periods.pdf" and "9J_Mode_Shapes_SLE.XLSX"8) Memorandum on Vertical Mat Foundation Springs, dated 11/13/179) Memorandum on Ground Motions, dated 11/21/17, with updated Figures 4 and 5 received 11/28/17

10) Revised Final Geotechnical Report, dated 11/08/1711) Report of Seismic Design Services, dated 1/4/1812) Report of Seismic Design Services, dated 1/22/18

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Submittal: Draft Memorandum - 9th & John Apartments - Site Specific Ground Motion Procedures, dated 07/12/17

1 Approach forevaluating site-specificresponse spectra andground motions

Page 1 08/15/17 This memorandum presents GeoEngineer's approach for evaluating site-specific response spectra andground motions in support of the design of the proposed 9th and John project. The approach isgenerally consistent with the procedures outlined in ASCE 7-16.

08/23/17 Comment noted. 08/24/17 Resolved.

2 Shear Wave VelocityProfiles and SubsurfaceConditions

Page 1, Figures 2 and 3. 08/15/17 Shear wave velocity profiles have been provided from Microtremor measurements at 9th & John site, aswell as suspension logging results for the nearby Block 48 site and the more distant SR99 Bored Tunnelproject. The suspension logging results have much more variability than the microtremor results asshown in Figure 2. GeoEngineers has recommended ignoring the velocity results for the upper 32 feetof the Block 43 velocity results. The suspension logging shear wave velocities appear to be greater thanthe shear wave velocities determined by the microtremor measurements. The Block 48 measurementsare greater than 200 feet from the 9th & John site and the SR99 measurements are approximately 700to 800 feet away from the 9th & John site. Even though it has been proposed to give greater weight tothe site-specific microtremor measurements than to the suspension log measurements, the "best-estimate shear wave velocity" appears to be biased toward higher shear wave velocity values and thusbe unconservative in the ground motion evaluation.

08/23/17 The suspension PS log measurements were completed in the same geologic unit.The differences in shear wave velocity profiles between the suspension PS logsand the microtremor arrays are due to the natural variability in the glaciallyconsolidated soils and the differences in measrement technique. Including thesuspension PS log measurements in our shear wave velocity evaluation isprudent and adds robustness to it. It is our professional opinion that a 60%/40%weight distribution between the microtremor array and suspension logmeasuremnts appropriately accounts for the sources of uncertainty identifiedabove, and also recognizes that site-specific measurements should be weigthedhigher. As the engineer of record, we are comfortable with this. Note, we alsoconsider +/- one standard devaiation profiles, and the lower-boud profile islower than the site-specific microtremor array measurements.

08/24/17 SeeComments 11,12 and 13.

3 Site-SpecificProbabilistic SeismicHazard Analysis

Page 2 08/15/17 The proposed approach is generally acceptable. As this SPRP was not part of the 5th and Lenora andBlock 21 projects, please provide the documentation that the converted 2014 USGS SSC modelconverted to a format compatible with Haz45.2 was reviewed and approved.

08/23/17 It is our opinion that the results presented in Appendix B demonstratereasonable agreement between our implementation and the USGS results. IvanWong was the peer reviewier for Block 21 and 5th and Lenora, so only onereview was required. The Block 21 comment log (included in the supplementalinformation) documents the discussions the resolution of the review comments.Refer to Comment 32, specifically.

08/24/17 Resolved. SeeComment No.14

4 Ground Motion Models Page 2 08/15/17 The proposed ground motion models and weightings are acceptable. 08/23/17 Comment noted. 08/24/17 Resolved.

5 Evaluation of BasinEffect AmplificationFactors

Page 4 08/15/17 The outllined approach is acceptable. 08/23/17 Comment noted. 08/24/17 Resolved.

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6 Site-Specific Risk-Targeted Maximum-Considered EarthquakeResponse Spectrum


7 Conditioning Periodsfor CMS

Page 6 08/15/17 The two CMS periods appear appropriate based on the information provided. Should the periods andmass participation of the structure change based on additional analyses, the CMS periods should be re-evaluated.

08/23/17 We will reach out to the project structural engineer to confirm the conditioningperiods prior to developing the CMS. This will occur after the the MCER and SLEspectra are approved.

08/24/17 Resolved.

8 Ground MotionSelection andModification


Submittal: Microtremor Array Measurements, by OYO Corporation

9 Report by OYOCorporation

08/17/17 The report is acceptable. XX/XX/XX Comment noted. 08/24/17 Resolved.

Submittal: Revised Master Use Permit Report

10 Report byGeoEngineers

08/17/17 The report is acceptable. XX/XX/XX Comment noted. 08/24/17 Resolved.

Submittal: Memorandum on Ninth & John Apartments - Site Specific MCER and SLE Response Spectra, dated 08/21/17

11 Site-Specific MCE-RResponse Spectra

Figure 11 08/23/17 By e-mail:

Please provide a table showing the spectral values for the four MCE-R spectra depicted in Figure 11 ofthis memorandum.

One more question, how was the weighted average determined? What type of distribution wasassumed?

Was the standard deviation for the shear wave velocities (see attached Figure 3 from earlier submittal)also determined assuming a lognormal distribution?

Continued in Comment 12 below...

08/23/17 Response by e-mail from GeoEngineers:

Please refer to the attached Excel spreadsheet (identified as Document 6received 8/23/17).

The weighted-average was calculated based on the ln(Sa) values and assigning a20% weight to the +/- sigma values and a 60% weight to the best-estimatevalues. Specifically, Wt. Avg = exp[0.2*ln(-1sigma)+0.6*ln(best-estimate)+0.2*ln(+1sigma)].

No, sigma for shear wave velocity was assumed to be normally distributed. Thisis typical for geotechnical properties.

08/24/17 SeeComments 12and 13

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Figure 11 08/23/17 By e-mail:

Please refer to the Block 21 Comment Log you sent me. Ivan’s Comment No. 8, Question 3 states“…Ground motions are lognormally distributed just like velocities. Also I would suggest that you useweights of 0.2, 0.6, and 0.2 for the lower-range, best-estimate, and upper-range Vs30 values,respectively. These weights are standard weights used in estimating hazard representing the 5th, 50th,and 95th percentile values for a lognormal distribution.”

There is also a lot of literature that discusses shear wave velocities and mention that shear wavevelocities are lognormally distributed. I’ve attached one of Ivan’s publications. (Silva, Wong andDarragh, Engineering Characterization of Earthquake Strong Ground Motions in the Pacific Northwest inUSGS Professional Paper 1560, 1998)

Continued in Comment No. 13

08/23/17 Response by e-mail from GeoEngineers:

Thanks for pointing this out. We did consider a lognormal distribution of groundmotions during Block 21, but the velocities must have slipped through thecracks. The attached Figures 2* and 3* present our shear wave velocity profilesassuming a lognormal distribution of Vs. The -1sigma profile is increased asexpected based on an attenuated tail at the lower end of a lognormaldistribution. The best-estimate and +1sigma profile are practically the same.This is confirmed by comparing the Vs30 values computed from the mid-excavation depth for the original normally distributed profiles and the updatedlognormally distributed ones. See below.

Distribution Mid-Excavation Vs30 (ft/sec) -1sigma Best-Estimate +1sigmaNormal 1,647 2,046 2,426Lognormal 1,727 2,048 2,423% Difference 4.9 0.1 -0.1

We acknowledge that the literature indicates shear wave velocities arelognormally distributed. However, for practicality and project schedule, werecommend moving forward with the normally distributed Vs30 values if youapprove. Particularly, since the current -1sigma value is 5% conservative relativeto the lognormal version, and a difference of 5% in the -1sigma Vs30 is notexpected to significantly change the final MCER response spectrum.

08/24/17 See Comment13


Figure 11 08/24/17 We have considered the benefits of considering additional shear wave velocity data in the vicinity of thesite, especially when coming from the same geologic materials. However, past experience with shearwave velocity measurements using different methods (i.e., microtremor, suspension logging, downholelogging) at the same site have generally produced velocity profiles that have variability, but the variousprofiles have been similar to the median velocity profile. At Ninth and John, the two microtremorarrays have produced remarkably similar shear wave velocity profiles. The suspension logging resultsfrom Block 48 and the two SR99 locations have more variation and are consistently higher. Since thereare two shear wave velocity profiles for SR99, this may bias the statistics towards the higher values(40% for Ninth and John, 20% for Block 48, and 40% for SR99); also, sample size of 5 is very small andstatisitics become somewhat questionable. From the submittals, it appears that a normal or lognormaldistribution for the shear wave velocities will give similar results; however, the weighting of the PSHAresults (which are based heavily on the shear wave velocity profile used) may be biased because ofoverweighting of the SR99 results. Consideration could be given to adjusting the weighting factors forthe PSHA results, such as reducing the weighting for the Mean - 1 sigma results.

XX/XX/XX To clarify, the individual shear wave velocity measurements were not givenequal weight as is indicated by Comment 13 (i.e., 40% to 9th and John, 20% toBlock 48, and 40% SR99). Rather, a 60% weight was assigned to the 9th & Johnmeasurements and 40% to the suspension log measurements. The specificweighting used to develop the best-estimate shear wave velocity profile is asfollows: 60% for 9th and John (30% assigned to each of the two measurements),13% for Block 48, and 27% for SR99 (about 13% assigned to the twomeasurements). It is our opinion that an appropriate weight was assigned tothe site-specific 9th & John measurements for the development of the best-estimate shear wave velocity profile, and that the SR99 measurements are notoverstated. It is our opinion that a 60% weight assigned to the best-estimateUHS and 20% weights assigned to the +/- sigma profiles are also appropriate.This is also consistent with our practice on other ongoing peer reviewed projectsin downtown Seattle (i.e. 600 Wall Street reviewed by Stephen Dickenson and5th & Lenora reviewed by Ivan Wong).

08/30/17 See Comment16

Submittal: Comment Log for Block 21 Project, dated 03/20/17

14 Ground motioncomments by IvanWong

08/17/17 The Comment Log provides the information requested in Comment No. 3. XX/XX/XX Comment noted. 08/24/17 Resolved.

Submittal: Excel spreadsheet with MCE-R 5% damped Spectral Accelerations

15 Report byGeoEngineers

Comment 11 08/17/17 The spreadsheet provides the information requested in Comment 11. XX/XX/XX Comment noted. 08/24/17 Resolved.

Submittal: Excel spreadsheet with MCE-R 5% damped Spectral Accelerations

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16 GeoEngineers responseto Comment 13

Comment 13 08/30/17 We acknowledge the correct weightings of the best-estimate shear wave velocity profiles used byGeoEngineers stated in the response to Comment 13. The point that the SPRP was trying to make wasthat the results from SR99 were weighted too heavily compared to Block 48. There were 2 suspensionlogs from SR99 referenced whereas there was only 1 suspension log from Block 48. The velocity profilesfrom SR99 are generally higher in velocity compared to the Ninth and John and Block 48 sites. Inaddition, Block 48 is closer to Ninth and John than the SR99 route. It would be more appropriate toweight the Block 48 results equally with the SR99 route results (i.e., 20% for the Block 48 log and 10%each for the 2 SR99 logs).

XX/XX/XX Comment noted. 11/20/17 RESOLVED

Submittal: e-mail with attachments regarding "9J Proposed CMS Conditioning Periods.pdf" and "9J_Mode_Shapes_SLE.XLSX"

17 Proposed CMSConditioning Periodsand Mode Shapes fromSLE analysis

e-mail received 8/31/17 09/07/17 Please refer to Structural Comment No. 6 for SPRP concerns about the CMS.

The proposed CMS conditioning periods are tentatively approved. Should further analyses for the MCE-R indicate that the periods of the structure change significantly, adjustments may be needed for theconditioning periods. In addition, the envelope of the CMS spectra should not be less than 75% of theUniform Risk-Targeted Spectrum over the period range of interest, which covers periods with at least90% mass participation. The CMS spectra shall be submitted for SPRP review.


Submittal: Memorandum - Site-Specific Conditional Mean Spectra, dated 10/11/17

18 Conditional MeanSpectra Development

Pages 1-2 10/25/17 It is proposed to develop 2 condional mean specta for the site-specific MCE-R ground motion. Insteadof using a single CMS for 2 conditioning periods, it is proposed to generate 2 CMS spectra, one for shortperiods and one for longer periods, by combining individual scenario spectra at two short periods (0.1and 0.75 sec) and at two long periods (2.4 and 3.5 sec). The recommended short period CMS is theenvelope of the scenario spectra with conditioning perods of 0.1 and 0.75 sec with smoothing betweenthe conditioning periods to eliminate a local minimum. Similarly the recommended long period CMS isthe envelope of the scenario spectra with conditioning periods of 2.4 and 3.5 sec with smoothingbetween the two conditioning periods.

This procedure, although considered to be conservative for derivation of CMS sepctra, is acceptable.


19 Conditional MeanSpectra Development

Page 4 10/25/17 The individual scenario spectra for each conditioning period were constructed by weight-averaging thespectra for crustal, subduction-inter=face and subduction-intraface sources according to thedeaggregation results. This procedure is acceptable.


20 Ground MotionSelection

Page 6 10/25/17 It is proposed to select time histories for matching/scaling to the CMS spectra using an approachattributed to ASCE 7 instead of the procedure given in TBI 2.02 based on sources contributing morethan 20% of the hazard at the contributing period of interest. In consideration that the methodproposed for development of the two CMS spectra is inherently conservative, the ASCE 7 approach isacceptable.


21 Ground MotionSelection - short periodCMS ground motions

Table 8 10/25/17 The ASCE 7-16 approach is acceptable, however, the number of time histories for SeattleFault/Background and other crustal events appears to be overweighted compared to the SubductionIntraslab and Subduction Interslab events.

XX/XX/XX Comment acknowledged. It is noted that for the short-period CMS, the numberof ground motions associated with the contribution of the subduction intraslabsource varies between about 2 and 5 records across the two conditioningperiods per the seismic hazard deaggregation (Table 8). In our experience,subduction intraslab records rarely control building design during NLRHA whencompared to records from crustal (particularly near-field records) or subduction-interface sources. Accordingly, we developed a short-period CMS groundmotions suite that is more closely associated with the T=0.75s deaggregation.One subduction intraslab record was used and the remain contribution wasdistributed to the crustal sources. This resulted in a higher number of crustalrecords for this ground motions suite. A similar approach was used for the long-period CMS, whereby the contribution of the intraslab source was distributed tothe near-field crustal and subduction-interface sources because these recordstend to control long-period building response.

11/29/17 RESOLVED

22 Ground MotionSelection - long periodCMS ground motions

Table 9 10/25/17 The ASCE 7-16 approach is acceptable. The distribution of time histories is acceptable. XX/XX/XX Comment noted. 10/25/17 RESOLVED

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Submittal: Memorandum - Vertical Mat Foundation Springs, dated 11/13/17

23 Foundation Springs Memorandum 11/13/17 Please provide the spring calculations. XX/XX/XX Please refer to the calculations attached in the email dated 11/17/2017. Alsoattached are the reference equations per ASCE 41-13

11/20/17 RESOLVED;see Comment24

Submittal: e-mail response to Comment 23 from GeoEngineers, dated 11/17/17

24 e-mail response Calculations and ASCE41-13 pages

11/20/17 The response is accepted. The vertical mat foundation springs are acceptable. Comment noted. 11/20/17 RESOLVED

Submittal: Memorandum - Vertical Mat Foundation Springs - Revision 1, dated 11/20/17

25 Foundation Springs Memorandum 11/20/17 The Memorandum is acceptable. Comment noted. 11/20/17 RESOLVED

Submittal: Memorandum - Ground Motions, dated 11/21/17, with revised Figures 4 and 5 received 11/28/17

26 Ground MotionSelection Procedures

p. 1-2 11/29/17 The ground motion selection procedures are acceptable. 12/01/17 Comment noted. 12/04/17 RESOLVED

27 Ground Motion Suites p. 3, Tables 3A and 3B 11/29/17 The short-period CMS seed ground motions are acceptable. 12/01/17 Comment noted. 12/04/17 RESOLVED

28 Ground Motion Suites p. 4, Tables 4A and 4B 11/29/17 The long-period CMS seed ground motions are acceptable. 12/01/17 Comment noted. 12/04/17 RESOLVED

29 Ground MotionModificationProcedures

Page 4, Figures 1 and 2 11/29/17 Figures 1 and 2 both show value lines for "Average SRSS of 11 input Ground Motions." As confirmed bye-mail on 11/29, GeoEngineers will correct to state "Average of the Maximum-Direction Spectra for 11input Ground Motions" in the final report.

12/01/17 Comment noted. 12/04/17 RESOLVED

30 Ground MotionModificationProcedures

Page 4, Figures 1 and 2 11/29/17 The average of the Maximum-Direction spectra from all the ground motions satisfies Sect. 16.2.3.2 ofASCE 7-16.

12/01/17 Comment noted. 12/04/17 RESOLVED

31 Ground Motion Suites p. 4, Tables 4A and 4B 11/29/17 The long-period CMS seed ground motions are acceptable. 12/01/17 Comment noted. 12/04/17 RESOLVED

32 Time Histories Fig. 18d 11/29/17 Please re-plot the Acceleration time history for the FP component using the same time scale as theother plots.

12/01/17 Please refer to the revised Figure 18d transmitted via email on 12/1/2017 withthis response. We will incorporate the revised figure in the forthcoming finalseismic design report.

12/04/17 RESOLVED

33 Time Histories Short-Period CMS 11/29/17 The scaled acceleration time histories for the short-period CMS are acceptable. 12/01/17 Comment noted. 12/04/17 RESOLVED

34 Time Histories Long-Period CMS 11/29/17 The scaled acceleration time histories for the long-period CMS are acceptable. 12/01/17 Comment noted. 12/04/17 RESOLVED

Submittal: Revised Final Geotechnical Report, dated 11/08/17

35 Field Explorations Page 2 and Fig. 2 12/04/17 GeoEngineers drilled only one exploration boring on the site. SDCI should review if this is sufficient for asite of this size and project of this magnitude.

12/05/17 With glacially consolidated soils encountered at shallow depth, the use ofsoldier piles and tiebacks, and our extensive experience in SLU relative togroundwater, no changes with respect to design are expected with new borings.Also, we have access to the recently completed borings for the project acrossthe alley to the west that will provide more information to the earthwork andshoring contractors. Based on this, no additional borings are considerednecessary.

12/05/17 RESOLVED

36 Report 12/04/17 Other than Comment 35, Seismic Peer Review has no other comments on the Revised FinalGeotechnical Report.

Comment noted. 12/05/17 RESOLVED

Submittal: Report of Seismic Design Services, dated 1/4/18

37 Plot of scaled timehistories, Chi-ChiTaiwan 1999, TCU051

Fig. 91d 01/08/17 FP Acceleration Time History should be plotted to the same time scale as the other time histories. 01/22/18 Please refer to our revsied seismic report dated 1/22/2018. 01/24/18 RESOLVED

38 Report 01/08/17 Other than Comment 37, the report is acceptable. Comment noted. 01/24/18 RESOLVED

Submittal: Report of Seismic Design Services, dated 1/22/18

39 Plot of scaled timehistories, Chi-ChiTaiwan 1999, TCU051

Fig. 91d 1/24//18 FP Acceleration Time History has been plotted to the same time scale as the other time histories. 01/24/18 RESOLVED

40 Report 1/24//18 The report is acceptable. 01/24/18 RESOLVED

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