u.s. pharmacopeia headquarters consolidation...moment frames are used as the main lateral system. in...

U.S. Pharmacopeia Headquarters Consolidation Rockville, MD

Jeff Rothermel Structural Option

Advisor: Dr. Ali Memari Revised Thesis Proposal

Submitted: Jan. 20th, 2009

Thesis Proposal U.S. Pharmacopeia Headquarters Dr. Memari Rockville, MD

Table of Contents

Executive Summary ………………………………………………………………..……………1 Project Background ……………………………………………………………………………..2 Structural Systems Foundations …………………………………………………………………………….3 Floor Systems ……………………………………………………………………..3 Roof Systems ……...……………………………………………………………...4 Lateral System ……………………………………………………………………..4 Columns ……………………………………………………………………………..4 Beams ………………………………………………………………………….….6 Problem Statement …………………………………….……………………………………….7 Proposed Solutions ……………………………………………………………………………..7 Breadth Studies ...………………………………….………………………………………10 Solution Methods …..………………………………………………………………………..10 Tasks and Tools …...……………………………….………………………………………11 Project Timetable ………………………………………………………………………..…..12 Conclusions ………………………………………………………………………………..…..13 Appendix A ………………………………………………………………………………..…..14


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Executive Summary The U.S. Pharmacopeia Headquarters (USP) in Rockville, MD is a new consolidation of corporate office space and laboratories serving the organization. It is a 160,000+ ft2 building housing 5 stories of mixed office and laboratory spaces and a 19,000 ft2 conference center with auditorium. The office/lab tower is attached to an existing building owned by USP on site and the conference center wraps around to form an outdoor plaza space in the center.

The current system is an 8” mildly reinforced concrete two way flat plate with some

drops, which is very common in the Washington, DC area. 24”x24” columns are used throughout with adjustments at the exterior. These columns make up the lateral system through moment frames. The problems looked at are the high 14’ floor heights with only a 9’ ceiling height, and the 22’ column grid which is rather small.

The proposed solutions offer a different method in an attempt at working out the issues

considered. They look at systems which may not be very common in the area and hopefully turn out to be a better design. The proposed systems are a two way PT slab, a one way slab with PT beams, and a staggered steel truss system. The staggered steel trusses may be looked at in a variety of layouts as well. All three alternatives may affect the lateral system and the lateral system may be able to get much smaller. The different solutions have various many architectural implications as well. The steel trusses may interfere with the aesthetic of the open office plan or it may contribute to spatial effects. A mechanical breadth was deemed necessary in an attempt to slim down floor thickness by reducing duct sizes. The second breadth chosen was construction do to the impacts the new systems would have on scheduling and costs.

The steel truss solution will employ concepts of AE 534, and 597A. The steel

connections will be designed and the members will be checked using SAP or ETABS. Also the concrete solutions will use AE 597A concepts by modeling in SAP and ETABS for lateral design.

The final design results will be compared against each other and existing, and a

recommendation on the final systems to be used will be made.


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U.S. Pharmacopeia Headquarters Thesis Proposal 12601 Twinbrook Parkway Rockville, Maryland

U.S. Pharmacopeia (USP) is a nonprofit organization devoted to the testing of drugs and drug compounds in order to create the standards used in manufacture. They create the standards by which the FDA compares drugs much like ASTM creates the standards which our engineering materials are rated against.

Last year the newest addition to their vast resources was completed with a brand new office, lab and conference space in Rockville, MD. The new USP Headquarters building houses 141,000 ft2 of office and lab space and 19,000 ft2 of new conference space. The lab and office space occupies 5 levels all roughly 241’ x 174’. Both structures sit atop 3 levels of below grade parking that aligns with below grade parking under the existing building. USP’s contemporary structure replaces two older buildings on site and combines with one remaining existing building to form a completely enclosed space surrounded by USP office space. The conference center arcs around from one end to completely enclose an outdoor plaza space. Both new buildings connect to the existing building to form a single, complete structure. One of the most prominent features is the conical auditorium which stands proudly on the busy street corner.

Site Plan


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Structural Systems

Foundations

Beneath the parking levels the columns for the building sit mainly on spread footings ranging from 7’x7’x2’-1” (l x w x h) up to 15’x15’x2’-9”. There are several rectangular footings and combined footings that range from in width, height and depth from 11’-19’, 25’-8”-33’8” and 36”to 48” respectively. There are mat foundations spread throughout the structure being 30” and 36” typically. At the G2 level which is the deepest, footings bear on decomposed rock with an allowable bearing pressure of 8000 psf, while at the G1 level the footings bear on silty sand with an allowable bearing of 3000 psf. Under the conference center and plaza area the maximum depth is 15’-8” below grade to top of footings and under the office building they lie at a maximum of 20’-3” below grade. Footings beneath the office/lab building are generally much smaller than those below the conference center. Figure A-2 shows the footing plan for the office tower.

Below grade perimeter walls are made from cast-in-place reinforced concrete. Wall thicknesses range from 12” around the parking ramp to 20” around the North end of the office building with typical footings of 3’x 1’-2”. Along the East and North 36”x12” columns are poured flush with the interior faces of the basement walls. The West side of the G2 parking level has existing grade beams and footings; these were underpinned to remain in place.

The G2 parking level has 5” slab on grade construction. Slab on grade is reinforced with welded wire fabric reinforcement. A 2” expansion joint is provided to separate the conference center portion and office portion of level G1. Floor Systems

The standard floor system used throughout the building is two-way flat slab with drop panels. Typically floor slabs through the parking levels and office levels are 8” slab with a bottom mat of #4’s@ 12” on center each way. On the G1 level the drop panels are typically 10’x10’x3½” and 5½” thick beside the underpinned existing foundation. The Ground floor uses the same floor framing with some thicker drops depending on loading. The loading dock on the East side has a 20” slab at this level with continuous drops beneath it. The central columns under the office building slope to the 22’ column grid at the Ground level inside the parking area. At the first floor is the plaza space, the conference center floor, and the main entrance floor of the office building. Conference center and plaza slabs are normal 10” thick one way slabs increasing to 16” near the Northwest corner of the plaza. The plaza itself is constructed of up to 2’ of rigid insulation on top of slab finished with soil and the pavers that make the architectural pattern. The Second through Penthouse floors use the typical 8” slab depth with slight increases in depth at high loading areas. Floors 1 through 4 see many of the drop panels disappear on interior columns. Also on the second level at the connection between the office building and conference center there are 48”x48” post tensioned girders hanging columns below. Each floor of the office building has a connector with the existing Twinbrook 2 building. These are made of 10” one way slabs supported by 12”x24” mildly reinforced concrete beams and 4 24”x12” columns. Figures A-3 and 4 show existing structural floor plans.


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Roof Systems

The conference center and auditorium have a roof system made of moment frames made up mainly of W14x22’s, and W12x16’s. Various other shapes are used based on span. Sitting on top of the steel is a 3” composite steel deck with lightweight concrete. Topping off the conference center roof is an IRMA roofing system with green roof on top. IRMA is a reverse membrane system where the membrane sits on top of the concrete slab rigid insulation, ballast and green roof are placed on top. The structural roof slab is 3¼” lightweight concrete on 2” metal decking. Sedum is the vegetation of choice placed in an 8½” triangular spacing. W8x31’s make up the auditorium roof beams which are supported by 10 evenly spaced radial girders. The auditorium is made of 1½” type B steel decking with 3” rigid insulation. Topping it is plywood sheathing and a metal roof surface. The office building has a roof system of steel frames on top of concrete columns. W18x35’s, W12x16’s and W10x15’s make up the majority of roof beams with W12x19’s and W16x26’s acting as girders. Both the penthouse roof and the lower office roof are constructed of 3” type N steel deck covered by 5/8” gypsum roof sheathing, 3” rigid insulation, and ballast respectively. Figures A-5 and 6 in Appendix A show the existing roof plans. Lateral System

Resistance to wind and seismic loading in the USP building is provided in the office/lab building by the rigid concrete floor plates and columns. In the conference center one story steel moment frames are used as the main lateral system. In the office columns sit at a regular 22’ grid with the Northern bay being 25’ and the Western bay being 21’.

The conference center moment frames are comprised of stiffened seated connections and double angles with welded flange plates. Moment frames are employed on the East side of the conference center in the North-South direction with scattered East-West frames throughout the system. It is assumed that lateral support is provided through the conical concrete walls of the auditorium in the Southwest corner and the beams that frame into their embed plates. Columns

Throughout the entire building a fairly regular column grid is laid out at 22’ each direction with lines K-P being 30’ each, A-B and H-J at 25’ and a few at 20’ and 21’. Under the conference center columns begin at the G2 level as 24”x24” concrete columns with 8#10s in general. They continue up to First floor where the conference center floor and plaza level is. From there wide flange steel columns are used to frame the walls and roof of the conference center and auditorium. All of the steel columns are W12s which are mainly W12x40s but go as large as W12x170s. In the office and lab structure columns begin in the parking level G1 as 24”x24” concrete columns with 8#9s in the interior while 36”x12” columns with 6#10s are poured flush with the basement wall around the exterior. On the Ground floor the interior 24”x24” columns along column lines B, C, E and F slope 2’ to the First floor column grid. Figure C-1 shows the typical sloping column detail. Beginning at the First floor the columns of the office building drop 1 bar size and continue to the Third floor. Figure C-2 shows typical bar layouts for columns.


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Figure C-1 Figure C-2

At the Third floor column lines 1, and A end and the 24”x24” columns of B line and the exterior 36”x12” columns become 12”x24” columns with 6#9s as vertical reinforcement. These columns continue up to the penthouse roof with C line ending at the penthouse floor. Several piers come up at the penthouse level for mechanical dunnage. There are also many 12”x24” columns throughout the core holding up beams that frame out elevators, stairs and several openings. The columns in the office building are assumed to be the main lateral resisting frame for the structure as well. It is assumed that the columns that have drop panels along C line for example are lateral resisting since there are some columns interior that do not have drops at all. It’s assumed that this, along with spots of higher loading is the reasoning for selective drop placement. One of the special features is the columns at H-2 and H-3 on the First floor. They are two 24”x24” concrete columns hung from post tensioned girders on the Second floor. Columns G-2 and G-3 are transferred out at the Second floor from the same girders. Figure PT-1 shows the girders in plan and PT-2 gives details of this unique feature.


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Figure PT-1 Figure PT-2 Beams

Various mildly reinforced concrete beams are used throughout the entire building. Under the plaza and conference center is a beam supported one way slab system using mainly 28”x48” concrete beams. Beams are used mainly around the stairways and elevator shafts however, and are not a dominant feature save the plaza and conference floors. As illustrated by Figures PT-1 and PT-2 above there are 2 unique transfer girders on column lines 2 and 3 on the Second floor. They are 48”x48” post tensioned transfers with PT columns hung below at midspan and two columns being transferred out at G line. They have PT of 52 and 56 strands each, providing 1404 kips and 1512 kips at line 2 and 3 respectively. Beams range anywhere from 12”-60” wide and 16”-54” deep throughout the building.


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Problem Statement

The problem to be addressed is the floor to floor heights in conjunction with the column grid. The floor to floor height of the office and lab spaces is 14’ with only a 9’ ceiling height. The majority of floor thickness is taken up by the mechanical ductwork and empty space. Being a lab space it requires very large ducts, the main supply duct that runs vertical being 108”x80”. The largest that run horizontal are 52”x24” this leaves about 2’ of space between ducts and ceiling. Also at 22’x 22’ the column grid is rather small, requiring a lot of columns. The building currently uses lots of vertical space to obtain the required area and a lot of structure to do the job.

Proposed Solutions

The solution is to try to reduce floor heights, thereby reducing façade and construction quantities and costs. Also increasing the column grid size will lead to a cheaper, faster build by reducing amount of pieces to build and the amount of structure for subcontractors to work around. Another gain of decreased column numbers is the opening up of the interior. With large open office plans taking up about ¼ floor the reduction in columns will increase the open feeling of the spaces and make them more light and enjoyable.

Alternative 1 is to change the mild two way flat slab to a post tensioned flat plate without any drops. The PT slab will double from a 22’x22’ column grid to 44’x44’. This will eliminate over half the columns and roughly maintain the structural floor depth. The slab may need to be increased from 8” to 10”-12” though if ductwork can be reduced by more there will be an overall gain. If there can be a gain of ≈2 ½’ per floor another floor can be added. Shear walls will be considered to alleviate columns from handling lateral thereby reducing their size. Figure PT-3 shows the typical layout for tendons in a PT slab.

Alternative 2 would be to use PT means under a 1 way slab system. The slab could be slimmer though the beams add greatly to overall depth. Even though the structure may be thicker every other row of columns could be removed so that if beams were oriented in the long direction of the building it would mean a great many columns could be removed. Figures PT-4 and 5 represent the typical bay of this alternative. Again shear walls will be considered in this alternative.

Alternative 3 would be a staggered steel truss system. Staggered steel truss systems consist of floor height trusses that are staggered such that hollowcore planks span from top chord of one to bottom chord of another. They utilize simple hollowcore plank as the floor diaphragm and the trusses make the supports. The trusses are supported on the ends to columns in the weak direction, and in the strong direction moment frames. This system would maintain roughly the same structural floor thickness and at the same time eliminate many interior columns. It would form a built in lateral system as well. The only drawback is with the reduction of interior columns comes the addition of all the web members spanning from floor to ceiling. Also if this were to be setup it could be attempted to try a new method for lateral loads. Figure ST-1 shows the view in section of a staggered steel truss system and its typical lateral load path.


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Figures ST-2 and 3 show in elevation the typical layout required and the possible new layout. Notice the staggering is in the vertical plane rather than horizontal so that it will create an in plane shear path rather than requiring shear to cross back and forth between diaphragms.

Figure PT-3

Figure PT-4 Figure PT-5


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Figure ST-1 (Typical Load Path)

Figure ST-2 (Typical Elevation Layout) Figure ST-3 (Possible Layout)


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Breadth Studies

The redesign of USP’s Headquarter building would require not only a structural change. Much of the change involves shortening the floor heights. A mechanical study will be done to break USP into smaller zones. Forming smaller mechanical zones will reduce duct size in order to slim down the floor thickness. Mechanical redesign will proceed based on the International Mechanical Code 2006, and IBC 2006. The second breadth to be utilized is a construction breadth. For each system a cost analysis will be performed. Also scheduling will be performed for each solution. They will be compared against each other and against the actual data. Determination of optimal system based on construction considerations for final solution.

Solution Methods

In order to design the alternatives, hand calculations will be the primary preliminary methods used. All methods will be design to comply with ASCE 7-05 loading requirements. And all alternatives will use LRFD methods with the two concrete designs referencing ACI 318-08.

Different staggered steel trusses will need to be analyzed for the optimum design. The

columns and all members will be designed using the AISC Steel Construction Manual 13th Edition. Also for loading on the truss system AISC Design Guide 14: Staggered Truss Framing Systems will be used. For the staggered steel trust solution a study of the steel connections will be used in order to utilize concepts learned in AE 534. The steel system will utilize concepts learned in AE 597A by modeling in ETABS to further refine hand calculations. PT design will be assisted with RAM Concept. As well, PCA prestressing recommendations and methods will be used for hand calculations. PCA Slab may also need to be used for verification of one way slabs. The optimal system will be determined based on number of supports required, overall structural thickness, cost, and constructability requirements.

Construction costs will be estimated using RS Means guides considering location.

Scheduling programs such as Microsoft Project will be used to develop the network schedule. Mechanical systems will be designed to meet International Mechanical Code 2006 and IBC 2006.


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Tasks and Tools

I. Layout and design of alternate gravity systems Task 1. Design truss layout a. Sketch out different layouts b. Design hollowcore for gravity c. Design trusses for gravity d. Design columns for gravity e. Verify using SAP Task 2. PT slab a. Sketch out layout and determine grid b. Design slab for gravity c. Design columns for gravity Task 3. One way slab a. Sketch layout and determine optimum b. Design slab c. Design PT beams d. Design mild or PT girders. e. Design columns II. Lateral systems design Task 4. Determine lateral loading Task 5. Lateral analysis and design a. Perform ETABS analysis b. Resize steel members accordingly c. Design steel connections d. Size shear walls e. Size concrete columns for lateral load f. Determine SWs or MRFs for concrete III. Breadth studies Task 6. Mechanical design a. Create mechanical zones b. Determine mechanical loads c. Size AHUs and other equipment d. Resize ductwork Task 7. Construction Analysis a. Cost analysis b. Scheduling IV. Task 8. Final Conclusions Task 9. Presentation

Thesis Proposal

U.S. Pharm

acopeia Headquarters

Dr. M

emari

Rockville, M

D

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Project T

imetable

Task 1/12-1/16 1/19-1/23 1/26-1/30 2/2-2/6 2/9-2/13 2/16-2/20 2/23-2/27 3/2-3/6 3/9-3/13 3/16-3/20 3/22-3/27 3/30-4/3 4/6-4/10 4/13-4/17

1

2

3

4

5

6

7

8

9

10

1. Truss Gravity Design 2. PT Slab Design 7. Mechanical Design3. One Way Slab Design 8. Construction Analysis4. Lateral Loading 9. Final Conclusions5. Lateral Analysis and Design 10. Presentation

Weekly Schedule

6. System Comparison and Choice


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Conclusions

The USP Headquarters building will be a challenge to reconfigure. The design will need to be done comparing 3 different systems; PT slab, staggered steel trusses, and a one way slab with PT beams. Each will be done separately then compared against each other. The steel system is expected to provide more efficiency in weight and size, though the concrete solutions may prove to provide less overall structure. They will incorporate a new mechanical zoning and design to reduce ductwork. The mechanical system will need to be redesigned to accomplish the programming requirements and remain within code requirements. In changing around the structural systems, new lateral systems will be designed. The steel system will be completely new, though the concrete systems may be kept as moment frames if it is more efficient than shear walls. The new alternatives may be vastly different than the original design, requiring a complete structural overhaul. The conference center will be designed in the same system as well. The new alternatives will change the construction schedule greatly. The steel system will impact construction the most. It is expected that the steel system will be fastest due to having the most prefabrication in the hollowcore planks and steel trusses themselves. Upon completion of the various systems studies a final comparison and recommendation on optimal solution will be given.


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Appendix A: Typical Existing Framing Plans

Appendix A displays the various typical framing elements for the building.

Figure A-1 (Complete 1st Floor Plan w/ zoning)


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Figure A-2 (Typical Spread footings)


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Figure A-3 (One way slab system)


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Figure A-4 (Typical two way floor system)


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Figure A-5 (Conference center green roof)


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Figure A-6 (Penthouse roof)

u.s. pharmacopeia headquarters consolidation...moment frames are used as the main lateral system. in...

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