Slide 1

AISC Seismic Provisions 1 James O. Malley Senior Principal, Degenkolb Engineers and Chair, AISC TC9 Changes to the 2010 AISC Seismic Provisions Slide 2 AISC Seismic Provisions 2 TC 9 The Hardest Working Committee in Show Biz Roy Becker (05)Roy Becker (05) Michel Bruneau (10)Michel Bruneau (10) Greg DeierleinGreg Deierlein Rick DrakeRick Drake Mike EngelhardtMike Engelhardt Roger Ferch (05)Roger Ferch (05) Tim Fraser*Tim Fraser* Subhash GoelSubhash Goel Jerry Hajjar (10)*Jerry Hajjar (10)* Ron Hamburger (10)Ron Hamburger (10) Jim HarrisJim Harris Pat Hassett (10)Pat Hassett (10) John Hooper (10)John Hooper (10) Brian Knight (10)Brian Knight (10) Keith Landwehr (10)Keith Landwehr (10) Roberto LeonRoberto Leon Bob Lyons (05)Bob Lyons (05) Sanj MalushteSanj Malushte Bonnie Manley (10)*Bonnie Manley (10)* Hank Martin (05)*Hank Martin (05)* Clarkson PinkhamClarkson Pinkham John Rolfes (10)John Rolfes (10) Rafael Sabelli*Rafael Sabelli* Mark Saunders*Mark Saunders* Tom Sabol Bahram Shahrooz Bob Shaw* Lee Shoemaker Lee Shoemaker Kurt Swensson Kurt Swensson Robert Tremblay (10) Jamie Winans (10) Cindi Duncan ** Plus Corresponding Members * SC Chair ** Secretary Slide 3 AISC Seismic Provisions 3 AISC 341 (2005 and 2010) AISC 341-05 was now included by reference in 2006 and 2009 IBC. Same for AISC 360.AISC 341-05 was now included by reference in 2006 and 2009 IBC. Same for AISC 360. AISC 360-10 and 341-10 are included by reference in 2012 IBC.AISC 360-10 and 341-10 are included by reference in 2012 IBC. Both the 2005 and 2010 Provisions will be summarized together to highlight update of newest attractionsBoth the 2005 and 2010 Provisions will be summarized together to highlight update of newest attractions > Presentation based on order of 2005 Edition > Focus of discussion on 2010 changes Slide 4 AISC Seismic Provisions 4 Overall Philosophy of AISC 341 Identify Target Yield Mechanism for Each SLRSIdentify Target Yield Mechanism for Each SLRS Designate Deformation-Controlled Elements (Structural Fuse):Designate Deformation-Controlled Elements (Structural Fuse): Design for Reduced Seismic Forces Ductility Design Is Relatively Straightforward (Prescriptive) Design Remaining Elements as Force-Controlled: Design for Forces to Remain Essentially Elastic at Capacity of FusesDesign Remaining Elements as Force-Controlled: Design for Forces to Remain Essentially Elastic at Capacity of Fuses Use Either Local or Global Approach Capacity Design Requires Good Judgment and Experience Credit: C. M. Uang Slide 5 AISC Seismic Provisions 5 Its This Simple Target Mechanism Plus Ductility Requirements Plus Capacity Design Requirements Equals Target Yield Mechanisms Flexural Yielding Tensile Yielding/Buckling Shear Yielding Slide 6 AISC Seismic Provisions 6 Major Elements of 2005 Seismic Provisions Part I covers all Major Seismic SystemsPart I covers all Major Seismic Systems > Focus on SDC D, E and F Coordinated with ASCE 7-05Coordinated with ASCE 7-05 Incorporate Post-Northridge FindingsIncorporate Post-Northridge Findings > FEMA/SAC Project Results (FEMA 350 Series) as Well as Other Efforts Composite Provisions from NEHRP Included (Part II)Composite Provisions from NEHRP Included (Part II) Note that Both Parts are in the Unified Format similar to the Main AISC SpecificationNote that Both Parts are in the Unified Format similar to the Main AISC Specification > Both LRFD and ASD included in one set of provisions Slide 7 AISC Seismic Provisions 7 Summary of Major Changes in AISC 341-10 Re-organized to be More Consistent with AISC 360-10Re-organized to be More Consistent with AISC 360-10 Format for Various Systems Have Been StandardizedFormat for Various Systems Have Been Standardized Incorporates AWS D1.8Incorporates AWS D1.8 Puts Composite Construction on the Same Footing as Steel (No more Parts I and II)Puts Composite Construction on the Same Footing as Steel (No more Parts I and II) Adds Two New Cantilever Column SystemsAdds Two New Cantilever Column Systems Developing design/analysis provisions explicitly follow capacity design approach for ALL systemsDeveloping design/analysis provisions explicitly follow capacity design approach for ALL systems Updates to member and system requirementsUpdates to member and system requirements Coordinated with ASCE 7-10. To be included in 2012 IBCCoordinated with ASCE 7-10. To be included in 2012 IBC Slide 8 AISC Seismic Provisions 8 Document Re-organization A. General RequirementsA. General Requirements > A1. Scope (I-1, II-1) > A2. References (I-2, II-2) > A3. Materials (I-6, I-7, II-5) > A4. Structural Design Drawings and Specifications (I-5, II-18) B. General Design RequirementsB. General Design Requirements > B1. General Seismic Design Requirements (I-3) > B2. Loads and Load Combinations (I-4, II-4) > B3. Design Basis (I-3) > B4. System Type Slide 9 AISC Seismic Provisions 9 Document Re-Organization (Cont.) C. AnalysisC. Analysis > C1. General Requirements > C2. Additional Requirements > C3. Nonlinear Analysis D. General Member and Connection Design RequirementsD. General Member and Connection Design Requirements > D1. Member Requirements (I6-I9, II8) > D2. Connections (I7, I8, II-7) > D3 Deformation Compatibility of Non-SFRS Members and Connections > D4. H-Piles (I-8) Slide 10 AISC Seismic Provisions 10 Document Re-Organization (Cont.) E. Moment-Frame SystemsE. Moment-Frame Systems > E1. Ordinary Moment Frames (I-11) > E2. Intermediate Moment Frames (I-10) > E3. Special Moment Frames (I-9) > E4. Special Truss Moment Frames (I-12) > E5. Ordinary Cantilever Column Systems > E6. Special Cantilever Column Systems Slide 11 AISC Seismic Provisions 11 Document Re-Organization (Cont.) F. Braced-Frame and Shear-Wall SystemsF. Braced-Frame and Shear-Wall Systems > F1. Ordinary Concentrically Braced Frames (I-14) > F2. Special Concentrically Braced Frames (I-13) > F3. Eccentrically Braced Frames (I-15) > F4. Buckling-Restrained Braced Frames (I-16) > F5. Special Plate Shear Walls (I-17) G. Composite Moment Frame SystemsG. Composite Moment Frame Systems > G1. Composite Ordinary Moment Frames (II-11) > G2. Composite Intermediate Moment Frames (II-10) > G3. Composite Special Moment Frames (II-9) > G4. Composite Partially Restrained Moment Frames (II-8) Slide 12 AISC Seismic Provisions 12 Document Re-Organization (Cont.) H. Composite Braced Frame and Shear-Wall SystemsH. Composite Braced Frame and Shear-Wall Systems > H1. Composite Ordinary Braced Frames (I-13) > H2. Composite Special Concentrically Braced Frames (II-12) > H3. Composite Eccentrically Braced Frames (II-14) > H4. Composite Ordinary Shear Walls (II-15) > H5. Composite Special Shear Walls (II-16) > H6. Composite Special Plate Shear Walls (I-17) I. Fabrication and ErectionI. Fabrication and Erection > I1. Shop and Erection Drawings (I5, App. W, II-18) > I2. Fabrication and Erection (I7) Slide 13 AISC Seismic Provisions 13 Document Re-Organization (Cont.) J. Quality Control and Quality AssuranceJ. Quality Control and Quality Assurance > J1. Scope (I-18, App Q, II-19) > J2. Fabricator and Erector Documents (App. Q) > J3. Quality Assurance Agency Documents (App. Q) > J4. Inspection and Nondestructive Testing Personnel (App. Q) > J5. Inspection Tasks (App. Q) > J6. Welding Inspection and Nondestructive Testing (App. Q) > J7. Inspection of High-Strength Bolting (App. Q) > J8. Other Steel Structure Inspections (App. Q.) > J9. Inspection of Composite Structures > J10. Inspection of H-Piles Slide 14 AISC Seismic Provisions 14 Document Re-Organization (Cont.) K. Prequalification and Cyclic Qualification Testing ProvisionsK. Prequalification and Cyclic Qualification Testing Provisions > K1. Prequalification of Beam-to-Column and Link-to- Column Connections (App. P) > K2. Cyclic Tests for Qualification of Beam-to-Column and Link-to-Column Connections (App. S) > K3. Cyclic Tests for Qualification of Buckling- Restrained Braces (App. T) Slide 15 AISC Seismic Provisions 15 Scope Statement / Genl Reqts. Intended Primarily for Building StructuresIntended Primarily for Building Structures > Also incorporated for building like non-building structures > Glossary clarifies that SLRS includes diaphragm chords and collectors, and all elements that resist seismic loads For SDC A, B and C, designer has choiceFor SDC A, B and C, designer has choice > Use the Seismic Provisions with appropriate R factor > Use AISC LRFD/ASD Provisions with R=3 Required When Specified by ASCE 7-10Required When Specified by ASCE 7-10 > SDC D, E, and F, typically > Clarifies use of ACI 318 for R/C elements in composite systems Slide 16 AISC Seismic Provisions 16 General Design Requirements SDC, Height Limitations, Design Story Drift per ASCE 7 -10SDC, Height Limitations, Design Story Drift per ASCE 7 -10 Defines how to apply 0 and E mh in ASCE 7-10,Defines how to apply 0 and E mh in ASCE 7-10, Required Strength either generated by analysis or the system requirements (capacity based design concepts)Required Strength either generated by analysis or the system requirements (capacity based design concepts) Available Strength per LRFD or ASDAvailable Strength per LRFD or ASD Slide 17 AISC Seismic Provisions 17 Project Documentation Requirements New Section to Define Expectations of:New Section to Define Expectations of: > Design drawings and specifications > Shop Drawings > Erection Drawings Requirements for Shop and Erection Drawings moved to Chapter JRequirements for Shop and Erection Drawings moved to Chapter J Includes lists of information to be provided such as SLRS designation, connection detailing, welding requirements, protected zones, etc.Includes lists of information to be provided such as SLRS designation, connection detailing, welding requirements, protected zones, etc. Consistent with FEMA 353 and AWS D1.8 references incorporated in 2010Consistent with FEMA 353 and AWS D1.8 references incorporated in 2010 Slide 18 AISC Seismic Provisions 18 Material Specifications ASTM Specifications for Materials EmployedASTM Specifications for Materials Employed > All major structural products incorporated Material Properties for Determination of Required Strength for Connections or Related Members Based on Expected Yield Strength and Expected Tensile Strength (R y and R t )Material Properties for Determination of Required Strength for Connections or Related Members Based on Expected Yield Strength and Expected Tensile Strength (R y and R t ) Available Strength to consider both expected yield and tensile strengthsAvailable Strength to consider both expected yield and tensile strengths > Intent is to ensure expected inelastic response and ductile failure modes Slide 19 AISC Seismic Provisions 19 Material Specifications (Cont.) Requirements for Charpy V-notch testing of heavy shapes and platesRequirements for Charpy V-notch testing of heavy shapes and plates Expand use of yield strength above 50 ksiExpand use of yield strength above 50 ksi Reference to AWS D1.8 for filler metalsReference to AWS D1.8 for filler metals Slide 20 AISC Seismic Provisions 20 Connections - Bolted Joints Fully Tensioned HSB, Class A Slip-Critical, design for bearing strength.Fully Tensioned HSB, Class A Slip-Critical, design for bearing strength. No sharing of load with welds in a joint or the same force component in a connection.No sharing of load with welds in a joint or the same force component in a connection. Standard holes, or short slots perpendicular to line of force.Standard holes, or short slots perpendicular to line of force. > Oversized holes in one ply of brace diagonals allowed > Other conditions allowed if verified by testing Ductile limit - state controls design.Ductile limit - state controls design. > Yielding rather than fracture > Removed in 2010 Slide 21 AISC Seismic Provisions 21 Connections - Welded Joints New Appendix W with welded joint requirements beyond standard AWS D1.1New Appendix W with welded joint requirements beyond standard AWS D1.1 > Consistent with FEMA 353 > Being incorporated into new AWS D1.8 Published in late 2005. Future editions of AISC Seismic will reference as appropriate. Referenced in 2010.Published in late 2005. Future editions of AISC Seismic will reference as appropriate. Referenced in 2010. WPS required / Approved by EORWPS required / Approved by EOR Continuity plate welding and detailing specifiedContinuity plate welding and detailing specified Slide 22 AISC Seismic Provisions 22 Connections - Welded Joints Filler metal CVN 20 ft.-lbs. @ -0 F for all welds in the seismic load resisting system (SLRS)Filler metal CVN 20 ft.-lbs. @ -0 F for all welds in the seismic load resisting system (SLRS) > Reduction from -20 F in 2002 Two level toughness required for designated Demand Critical Welds in SMF, IMF, OMF and EBFTwo level toughness required for designated Demand Critical Welds in SMF, IMF, OMF and EBF > based on FEMA recommendations > Consistent with previous testing > Appendix provides requirements for qualification Referred to AWS D1.8. Locations defined in AISC 341Referred to AWS D1.8. Locations defined in AISC 341 Slide 23 AISC Seismic Provisions 23 Welded Joints (cont.) Defines term Protected Zone where special care is requiredDefines term Protected Zone where special care is required > Eliminates welding and other attachments in plastic hinge zones (shear studs, e.g.). Spot welds acceptable OK outside hinge zones, but need to verify net section strengthOK outside hinge zones, but need to verify net section strength > Discontinuities caused by welding or other construction operations must be repaired. > Locations of Protected Zones defined for each system Fracture Shear Stud weld Slide 24 AISC Seismic Provisions 24Members Width-thickness ratios often stricter than main specification requirementsWidth-thickness ratios often stricter than main specification requirements 2010 Defines new terms, Moderately and Highly Ductile (MD and HD)2010 Defines new terms, Moderately and Highly Ductile (MD and HD) > Used for width-thickness and bracing reqts > Width-thickness table parallels B4.1 in AISC 360 > MD like compact, HD, like seismically compact > HSS values reduced due to test results > Boxed WF sections included > Composite elements included Slide 25 AISC Seismic Provisions 25 MrMr Moment Capacity p r Width-Thickness Ratio MpMp Plastic Buckling Inelastic Buckling Elastic Buckling ps Ductility Slide 26 AISC Seismic Provisions 26 Members Cont. New paragraph on diaphragm designNew paragraph on diaphragm design > Load transfer details required > Nominal shear strength defined as concrete above deck, w/o ACI Ch. 22, or test results Bracing requirements made uniform for various systemsBracing requirements made uniform for various systems > Special requirements at plastic hinges Columns with high axial load to be checked for amplified seismic loadingColumns with high axial load to be checked for amplified seismic loading > Similar to 341-05, but ALL columns checked for 0 level axial forces > New requirements for composite columns Slide 27 AISC Seismic Provisions 27 Column Splices/Bases Strength requirement for partial penetration and fillet welded splices of 200% of required strength.Strength requirement for partial penetration and fillet welded splices of 200% of required strength. Beveled transitions not required where partial penetration welds are permitted.Beveled transitions not required where partial penetration welds are permitted. Requirements for shear strength check of non-frame columns in all systems.Requirements for shear strength check of non-frame columns in all systems. > Only location in the provisions that refers to elements not part of the SLRS Clarifies use beveled transitions in CJP splices and removal of weld tabs (but not backing) per D1.8Clarifies use beveled transitions in CJP splices and removal of weld tabs (but not backing) per D1.8 > Column base weld backing reqts also defined Slide 28 AISC Seismic Provisions 28 Members (cont.) Column base design (Cont)Column base design (Cont) > General intent to design column base for same forces that the elements connecting to the base are designed for. Axial, shear and flexural strength requirements presentedAxial, shear and flexural strength requirements presented > Interaction with concrete elements referred to ACI 318 Appendix D. > Clarifying language added H-pile requirements includedH-pile requirements included Slide 29 AISC Seismic Provisions 29 Deformation Compatibility New Section highlights need to check non- SLRS members and connections for gravity load effects and deformations at the Design Story Drift as defined in ASCE 7-10New Section highlights need to check non- SLRS members and connections for gravity load effects and deformations at the Design Story Drift as defined in ASCE 7-10 > User Note added to justify shear tab connections and allow self-limiting inelastic deformations in other connections Slide 30 AISC Seismic Provisions 30 Chapter C Analysis (2010) Entirely new chapterEntirely new chapter Defines section properties for elastic analysesDefines section properties for elastic analyses > Elastic sections for steel > Cracked sections for concrete and composite elements Refers to system chapters for additional (capacity based requirements)Refers to system chapters for additional (capacity based requirements) Refers to ASCE 7-10 Chapter 16 when nonlinear analyses usedRefers to ASCE 7-10 Chapter 16 when nonlinear analyses used Slide 31 AISC Seismic Provisions 31 System Formats Unified in 2010! 1.Scope defines system title 2.Basis of Design defines expected system response (yielding and protected members etc.) 3.Analysis defines special analyses for capacity definitions (SCBF, e.g.) 4.System Reqts stability bracing and other system-wide reqts 5.Members sets b/t limits, lists protected zones and defines individual member reqts 6.Connections defines demand critical welds, and connection reqts, including splices Slide 32 AISC Seismic Provisions 32 Special Moment Frames (SMF) Designs based on cyclic test results to 0.04 radiansDesigns based on cyclic test results to 0.04 radians > Appendix S provides test requirements For either project specific or public testsFor either project specific or public tests > Appendix P provides basis for pre-qualification of connections > Connections designed in accordance with AISC 358 standard Shear connection capacity sufficient to develop force generated by fully plastic beamShear connection capacity sufficient to develop force generated by fully plastic beam Slide 33 AISC Seismic Provisions 33 (N) AISC Moment Connection Prequalification Standard Official title: Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic ApplicationsOfficial title: Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications > Developed by separate ANSI standards development committee (Ron Hamburger, Chair) Allows engineers to submit moment frame designs without producing connection test resultsAllows engineers to submit moment frame designs without producing connection test results > First edition focuses on RBS and End Plate connections More connections included (WUF-W, e.g.)More connections included (WUF-W, e.g.) Adopted by 2005 & 2010 AISC SeismicAdopted by 2005 & 2010 AISC Seismic Slide 34 AISC Seismic Provisions 34 SMF (Cont.) Panel Zone DesignPanel Zone Design > Intended to share yielding with beam > Equation differs from FEMA 350 Doubler plate configurations may be adjusted to avoid k areaDoubler plate configurations may be adjusted to avoid k area Continuity plates to match tested configurationsContinuity plates to match tested configurations M p2 M p1 M p1 at column face M p2 at column face Slide 35 AISC Seismic Provisions 35 SMF (Cont.) SCWB Check required for SMF framesSCWB Check required for SMF frames > Attempting to avoid weak stories > Exceptions provided > 2010 clarifies use of 0 for axial force reduction Column splices pushed towards CJPColumn splices pushed towards CJP M c2 M c1 M pc2 M pc1 C L C L Slide 36 AISC Seismic Provisions 36 SMF (Cont.) Lateral Bracing of BeamsLateral Bracing of Beams > Nominal bracing required along length for both strength and stiffness based on main spec. equations > Bracing at hinges (6%) required as well But, not IN hinge zones!But, not IN hinge zones! Slide 37 AISC Seismic Provisions 37 IMF/OMF Requirements Intermediate (IMF) provisions similar to SMFIntermediate (IMF) provisions similar to SMF > Tested capacity to 0.02 radians, beam shear, etc. > Other requirements (SCWB, panel zone, etc.) not as restrictive as SMF. MD designation for members. > DC welds at splices Ordinary (OMF) provisionsOrdinary (OMF) provisions > Allows calculation only, but for strength above 1.1 R y M p > Specific welding and detailing requirements (access holes, e.g.) Slide 38 AISC Seismic Provisions 38 STMF STMF Concept Similar to EBFsConcept Similar to EBFs Ductile Special Segment (SS)Ductile Special Segment (SS) Other Parts of the Truss Remain ElasticOther Parts of the Truss Remain Elastic Both Cross-braced and Vierendeel configurationsBoth Cross-braced and Vierendeel configurations Span limited to 65 feetSpan limited to 65 feet Depth limited to 6 feetDepth limited to 6 feet Minor change to SS capacityMinor change to SS capacity DC welds added for column splicesDC welds added for column splices Slide 39 AISC Seismic Provisions 39 Cantilever Columns (2010) Two (N) sections to be consistent with ASCE 7-10Two (N) sections to be consistent with ASCE 7-10 > (N) SDC and height limits in ASCE 7-10 Ordinary System (OCCS)Ordinary System (OCCS) > Column axial loads low (15% of available at 0 ) > AISC 360 b/t ratios, no DC welds or protected zones Special System (SCCS)Special System (SCCS) > HD b/t ratios, stability bracing for MD, protected zone at base, DC welds at base Slide 40 AISC Seismic Provisions 40 Special CBF Provisions KL / r < 4 / E/F y with exception to higherKL / r < 4 / E/F y with exception to higher Stricter b/t Ratios and Built-up Member RequirementsStricter b/t Ratios and Built-up Member Requirements Connection RequirementsConnection Requirements > Strength to Develop Tensile Strength > Ductility to Allow Buckling in Member or Gusset Plate Restrictions on Chevron and K-BracingRestrictions on Chevron and K-Bracing Stronger Column Splices RequiredStronger Column Splices Required Capacity Design Requires two load distributions be checkedCapacity Design Requires two load distributions be checked Connection Reqts. Increased (EBF and BRBF also), to accommodate driftConnection Reqts. Increased (EBF and BRBF also), to accommodate drift DC welds at column splices and bases. No PJP groove welded splicesDC welds at column splices and bases. No PJP groove welded splices Slide 41 AISC Seismic Provisions 41 2010 Analysis Reqt. - SCBF oF3oF3 oF2oF2 oF1oF1 T T 0.3P T 0 in Center Column Uplift in Center Column! F F F F F F0.3PT Slide 42 AISC Seismic Provisions 42 OCBF Provisions OCBF Provisions Limited use in high SDCsLimited use in high SDCs For V or inverted V, KL/r < 4.23/ E/F yFor V or inverted V, KL/r < 4.23/ E/F y Connection strength to develop brace tension capacity or amplified forceConnection strength to develop brace tension capacity or amplified force > Reorganized language to clarify expected compression strength Chevron bracing restrictionsChevron bracing restrictions Tension Only Bracing Systems Allowed for Low and PenthousesTension Only Bracing Systems Allowed for Low and Penthouses No K-Bracing & define minor eccentricities (similar for SCBFs)No K-Bracing & define minor eccentricities (similar for SCBFs) Slide 43 AISC Seismic Provisions 43 EBF Provisions EBF Provisions Inelastic behavior limited to link beamsInelastic behavior limited to link beams Remainder of system (braces and columns) to remain elasticRemainder of system (braces and columns) to remain elastic Best results for shear link elements, but local demands are higher than SMFsBest results for shear link elements, but local demands are higher than SMFs > Extensive stiffening requirements Built-up Boxes added for linksBuilt-up Boxes added for links > Based on recent Bruneau research Clarification on calc for inelastic rotation angleClarification on calc for inelastic rotation angle Other changes similar to SCBFOther changes similar to SCBF Slide 44 AISC Seismic Provisions 44 EBF Provisions (Cont.) Link-to-column connectionsLink-to-column connections > Require testing like SMF Exception allowedException allowed Beam outside link, braces and columns designed for link capacity, including strain hardening (1.25 & 1.1)Beam outside link, braces and columns designed for link capacity, including strain hardening (1.25 & 1.1) Lateral bracing requirements similar to SMFLateral bracing requirements similar to SMF > 6% at ends of links > Elsewhere, strength and stiffness as required in main spec. P br PuPu Slide 45 AISC Seismic Provisions 45 BRBF Provisions BRBF FramesBRBF Frames SCBF development improves braced frame performance, but still limited by brace buckling SCBF development improves braced frame performance, but still limited by brace buckling Concept developed in Japan, with many applicationsConcept developed in Japan, with many applications > Hysteretic behavior similar to elastic - perfectly plastic Development of provisions in U.S.Development of provisions in U.S. > Joint AISC/SEAOC effort Approach similar to EBFApproach similar to EBF > Analytical work indicates good performance > U.S. practice will lead to larger drifts > Included in 2003 NEHRP Slide 46 AISC Seismic Provisions 46 BRBF Provisions (cont.) Steel core restrained from bucklingSteel core restrained from buckling > Braces tested for twice Design Story Drift Appendix T specifies testing requirementsAppendix T specifies testing requirements > Brace strength addresses strain hardening and compression strength increase due to confining system Connections designed for adjusted strengthConnections designed for adjusted strength Chevron requirements less demanding than SCBFChevron requirements less demanding than SCBF Column splices similar to SCBFColumn splices similar to SCBF Increased Connection Reqts, DC welds at column splices and base, and no PJP groove welded splices similar to SCBFIncreased Connection Reqts, DC welds at column splices and base, and no PJP groove welded splices similar to SCBF Slide 47 AISC Seismic Provisions 47 SPSW Provisions SPSW like plate girder design approach (tension field theory)SPSW like plate girder design approach (tension field theory) Can generate tremendous strength and stiffness as compared to CBF Can generate tremendous strength and stiffness as compared to CBF SPSW concept developed in CanadaSPSW concept developed in Canada NBCC Code provisions in placeNBCC Code provisions in place > UC Berkeley work as well > Provisions incorporated into 2003 NEHRP Panel Capacity Based on Simple FormulaPanel Capacity Based on Simple Formula > Includes panel aspect ratio L/h between 0.8 and 2.5L/h between 0.8 and 2.5 > Slide 48 AISC Seismic Provisions 48 SPSW Provisions (cont.) Panels with Openings to have boundary elements (BE)Panels with Openings to have boundary elements (BE) Connection between web and BEs for plate capacityConnection between web and BEs for plate capacity BEs to develop panels. OMF style connectionsBEs to develop panels. OMF style connections Lateral bracing spacing like SMF.Lateral bracing spacing like SMF. Vertical BEs also have bending stiffness requirementsVertical BEs also have bending stiffness requirements Perforated Webs and corner cut-outs addedPerforated Webs and corner cut-outs added Added HBE stiffnessAdded HBE stiffness Protected zones addedProtected zones added Increased Connection Reqts, DC welds at column splices and base, and no PJP groove welded splices similar to SCBFIncreased Connection Reqts, DC welds at column splices and base, and no PJP groove welded splices similar to SCBF Slide 49 AISC Seismic Provisions 49 Composite Systems Part II - Composite Construction ProvisionsPart II - Composite Construction Provisions > First Developed for 1994 NEHRP > Identifies Numerous System Options (10 total in 2010) > Provides Detailed Requirements for Member and Connection Design > Modified and Made Consistent with Part I No longer Part II. Made Fully Consistent with Chapters E and FNo longer Part II. Made Fully Consistent with Chapters E and F > MANY changes required Slide 50 AISC Seismic Provisions 50 SRC Beam-Columns:SRC Beam-Columns: > Moderately and highly ductile detailing procedures (comparable to AISC 341-05) CFT Beam-Columns:CFT Beam-Columns: > Shear strengths is based on steel section alone Connections:Connections: > Non-seismic provisions include clearer text on load transfer for general composite conditions: Bond interactionBond interaction Direct bearingDirect bearing Steel anchorsSteel anchors > Non-seismic provisions include new provisions for steel anchors in shear, tension, and interaction for conditions beyond composite beams > Splice connection provisions for SRC refer to ACI Ch. 21 provisions for mechanical splicing > Seismic connection detailing provisions are mainly for steel girders framing into RC or SRC beam-columns Written in early 1990sWritten in early 1990s Chapter D: General Member and Connection Requirements Slide 51 AISC Seismic Provisions 51 Steel Anchors: Where steel headed stud anchors or welded reinforcing bar anchors are part of the intermediate or special SFRS of Sections G2, G3, G4, H2, H3, H5 and H6, their shear and tensile strength shall be reduced by 25% from the specified strengths given in Specification Chapter I.Steel Anchors: Where steel headed stud anchors or welded reinforcing bar anchors are part of the intermediate or special SFRS of Sections G2, G3, G4, H2, H3, H5 and H6, their shear and tensile strength shall be reduced by 25% from the specified strengths given in Specification Chapter I. > User Note: The 25% reduction is not necessary for gravity and collector components in structures with intermediate or special seismic force resisting systems designed for the amplified seismic load. Chapter D: General Member and Connection Requirements Slide 52 AISC Seismic Provisions 52 Composite Special Moment Frames C-SMF: Section G3 Composite or RC columns + steel, SRC or composite beamsComposite or RC columns + steel, SRC or composite beams Confine inelastic deformation to the girders and column bases with limited yielding in panel zones.Confine inelastic deformation to the girders and column bases with limited yielding in panel zones. Protected zones in inelastic region of girdersProtected zones in inelastic region of girders Demand critical welds at connections, splices and base platesDemand critical welds at connections, splices and base plates Other provisions are intended to limit or prevent excessive panel zone distortion, failure of connectivity plates or diaphragms, column hinging, splice failure, and local buckling that may lead to inadequate frame performance in spite of good connection performanceOther provisions are intended to limit or prevent excessive panel zone distortion, failure of connectivity plates or diaphragms, column hinging, splice failure, and local buckling that may lead to inadequate frame performance in spite of good connection performance SCWB similar to steel SMFSCWB similar to steel SMF Slide 53 AISC Seismic Provisions 53 Beam-to-composite column connections used in the SFRS shall satisfy the following requirements:Beam-to-composite column connections used in the SFRS shall satisfy the following requirements: > (1) Accommodate a story drift angle of at least 0.04 rad. > (2)The measured flexural resistance of the connection shall equal at least 0.80M p of the connected beam at a story drift angle of 0.04 rad. Composite Special Moment Frames C-SMF: Section G3 Composite CFT Moment-Resisting Connection Composite SRC Moment-Resisting Connection Slide 54 AISC Seismic Provisions 54 Composite Ordinary Shear Walls C-OSW: Section H4 Limited inelastic deformationLimited inelastic deformation Ensure yielding of the coupling beams in shear or flexureEnsure yielding of the coupling beams in shear or flexure Account for cracked section properties for concrete per ACI 318 Chapter 10 or ASCE 41Account for cracked section properties for concrete per ACI 318 Chapter 10 or ASCE 41 Structural steel or composite coupling beamsStructural steel or composite coupling beams May redistribute coupling beam forces up to 20% providedMay redistribute coupling beam forces up to 20% provided Vertical Redistribution of Coupling Beam Shear Slide 55 AISC Seismic Provisions 55 Significant inelastic deformationSignificant inelastic deformation > Ensure shear yielding of the coupling beams System requirements similar to C-OSW with the following exceptions:System requirements similar to C-OSW with the following exceptions: > Coupling beams yield over the building height followed by yielding at the base of the wall piers Apply a wall overstrength factor o to the wall design forcesApply a wall overstrength factor o to the wall design forces > The axial design strength of the wall at the balanced condition (P b ) shall equal or exceed the sum of 1.1R y V n of the coupling beams > Use 1.1R y V n or 1.1R y V p to compute the embedment length (L e ). Composite Special Shear Walls C-SSW: Section H5 Slide 56 AISC Seismic Provisions 56 Typical Coupling Beam Detailing Slide 57 AISC Seismic Provisions 57 Inelastic deformation capacity through yielding in the steel plate webs (steel alone is used to assess strength) and yielding of the vertical boundary element (VBE) at the baseInelastic deformation capacity through yielding in the steel plate webs (steel alone is used to assess strength) and yielding of the vertical boundary element (VBE) at the base Demand critical welds for splices, base plates, and HBE-to-VBE connectionsDemand critical welds for splices, base plates, and HBE-to-VBE connections Provisions for required strength in steel anchor connectorsProvisions for required strength in steel anchor connectors Detailing provisions refer to SPSWDetailing provisions refer to SPSW Composite Plate Shear Walls C-PSW: Section H6 Slide 58 AISC Seismic Provisions 58 QC and QA Detailed Appendix Q replaced general set of provisions in previous editions. (Changed to Chapter J in 2010)Detailed Appendix Q replaced general set of provisions in previous editions. (Changed to Chapter J in 2010) Consistent with FEMA 353 and AWS D1.8. References AWS D1.8Consistent with FEMA 353 and AWS D1.8. References AWS D1.8 QA plan required in conjunction with IBC Chapter 17. Covers both QA and QC.QA plan required in conjunction with IBC Chapter 17. Covers both QA and QC. Documentation requirements listedDocumentation requirements listed Visual Inspection Points and Frequency DefinedVisual Inspection Points and Frequency Defined > For before, during and after welding or bolting by both QA and QC. Shown in tabular format Observe, Perform and/or Document vs. Periodic/ContinuousObserve, Perform and/or Document vs. Periodic/Continuous NDT locations and requirements specified. Both UT and Magnetic Particle incorporated. All results documented.NDT locations and requirements specified. Both UT and Magnetic Particle incorporated. All results documented. Adds parallel composite construction requirementsAdds parallel composite construction requirements Slide 59 AISC Seismic Provisions 59 Status and Upcoming Activities AISC 341-10 approved by reference in ASCE 7-10, Supplement No. 1AISC 341-10 approved by reference in ASCE 7-10, Supplement No. 1 Included in 2012 IBCIncluded in 2012 IBC Work is underway on 2016 EditionWork is underway on 2016 Edition > To be referenced in ASCE 7-16 and 2018 IBC > First ballot to COS underway > Changes not as dramatic as 341-10, but > Public ballots next Spring, complete late next year Your comments/suggestions welcome!Your comments/suggestions welcome! Slide 60 AISC Seismic Provisions 60 AISC Documents Related to Seismic Design 2010 AISC Seismic Provisions (ANSI/AISC 341)2010 AISC Seismic Provisions (ANSI/AISC 341) > Available via download. 2010 AISC Moment Connection Prequalification Standard (ANSI/AISC 358).2010 AISC Moment Connection Prequalification Standard (ANSI/AISC 358). > Available via download. 2010 AISC Specification for Structural Steel Buildings (ANSI/AISC 360)2010 AISC Specification for Structural Steel Buildings (ANSI/AISC 360) > Available via download. 2012 AISC Seismic Design Manual2012 AISC Seismic Design Manual > Available for purchase. Work on 2018 underway. Slide 61Allows rapid incorporation of new information 2010 Provisions Another Step Forward (We HOPE!)2010 Provisions Another Step Forward (We HOPE!) > Format improved, technical updates and incorporates AWS D1.8 WE WANT YOUR INPUT AND RECOMMENDATIONS FOR IMPROVEMENTS!WE WANT YOUR INPUT AND RECOMMENDATIONS FOR IMPROVEMENTS!"> AISC Seismic Provisions 61 Concluding Comments Unified Process for Steel Seismic Provision DevelopmentUnified Process for Steel Seismic Provision Development > "Single Point of Responsibility" eliminates duplicative effort and minor differences that result in major confusion > Allows rapid incorporation of new information 2010 Provisions Another Step Forward (We HOPE!)2010 Provisions Another Step Forward (We HOPE!) > Format improved, technical updates and incorporates AWS D1.8 WE WANT YOUR INPUT AND RECOMMENDATIONS FOR IMPROVEMENTS!WE WANT YOUR INPUT AND RECOMMENDATIONS FOR IMPROVEMENTS!