1. Nijad Rudy Boukhalil structural option spring’05

2. Presentation outline Project background Project background Existing conditions Existing conditions Problem statement Problem statement Proposed solution Proposed solution Floor system Floor system Lateral system Lateral system vibration vibration Construction management Construction management Recommendations Recommendations Acknowledgements Acknowledgements questions questions

3. Project background  Location on the corner of Bellevue Way 5 stories  3 above ground  2 level parking 39,000 square foot Rectangular shape 131’x147’ Many openings Project cost = $14 million

4. Project background The museum has:  four classrooms for its Museum School  three interactive Explore Galleries  a 90-seat auditorium  a multimedia library  a Museum store  a small sidewalk café  2 story atrium  Outdoor terraces

5. Project background Project team  general contractor: Sellen construction Co.  mechanical design/build contractor: Mckinstry Co.  design architect: Steven Holl architects  Associate Architect: Sclater Partners Architects  structural engineer: Skiling Ward Magnusson barkshire, inc

6. Project background Architectural layout  3 galleries  3 light qualities  3 actions - see/explore/make (art, science, technology)  3 main levels  3 circulation directions

7. Existing conditions Floor system Composite steel deck 3.5” concrete3.5” concrete  normal weight concrete  compression strength fc’ = 4000 psi 3” metal deck3” metal deck shear studsshear studsAdvantages  Good with Long span  efficient and economic  Good strength to weight ratio  Smaller foundation needed Disadvantages  Crane demanding  Difficult coordination  vibration

8. Existing conditions Lateral system   Shear walls 10” Cast-in-place #5 reinforcing bars bearing walls along perimeter and core around openings and the atrium. Advantages:   The cast in place system: structure that is free of joints. achieve a continuous appearance of the applied finishes.   provide the architect with the desired architectural finish Shear walls

9. Existing conditions Seismic Load Calculations (ASCE 7-02)  Assumptions Occupancy Category:IIIOccupancy Category:III Seismic Use Group:IISeismic Use Group:II Site Class:DSite Class:D  Seismic response coefficient: R=6

10. Problem statement Seismic hazard effect: Seismic hazard effect: Half of the statesHalf of the states 109 million people109 million people 4.3 million businesses4.3 million businesses More frequent vibration  key issue for a museum More frequent vibration  key issue for a museum Original system Floor system: Composite floor Floor system: Composite floor Lightweight system  more subjected to vibrationLightweight system  more subjected to vibration Lateral system: Shear walls Lateral system: Shear walls Good choice against earthquakesGood choice against earthquakes Earthquake Cost damage: Earthquake Cost damage: Direct cost: $1 billion/yearDirect cost: $1 billion/year indirect business losses: $2 billion/yearindirect business losses: $2 billion/year

11. Proposed solutions floor system: How vibrations dies out Stiff diaphragm  share the earthquake forces Stiff diaphragm  share the earthquake forces Joist system  spacing 2ft o.c (for vibration) Advantages of joist  Lighter Weight reduce sizes of beams, columns reduce sizes of beams, columns Various sizes ~ Good for long spans Various sizes ~ Good for long spans Lowers the overall cost of the project Lowers the overall cost of the project  Construction Speeded Each joist is a complete and independent unit. Each joist is a complete and independent unit. Allows field work to progress efficiently. Allows field work to progress efficiently.

12. Proposed solutions Lateral system types of Lateral Systems  Bracing  Moment Frame Why choose brace frames  Have same advantages  used where shear walls are impractical. Advantages of Braced Frames:  High Strength and Stiffness  Minimizes Deflections  Uses less Material  Cost Effective ~ Efficient and Economical  Strong visual element  speedy erection for faster return.  More flexible to future changes than shear walls

13. Proposed solution Different types of bracings  Single Diagonals has to resist tension and compression caused by sideways forces in both directions on a frame. has to resist tension and compression caused by sideways forces in both directions on a frame.  Cross Bracing only need to resist tension only need to resist tension one brace is in tension for the sideways force in one direction on the frame,one brace is in tension for the sideways force in one direction on the frame, the other brace is in tension when the force is reversed.the other brace is in tension when the force is reversed. This is the most widely used type of bracing system. This is the most widely used type of bracing system.

14. Proposed solution  Advantages Allows for windows in walls, and other open spaces Allows for windows in walls, and other open spaces  Disadvantages Large deflections Larger Members Cost increase Why moment frames ok Obstructions rejectedObstructions rejected eliminates space limitations of solid shear walls braced frames.eliminates space limitations of solid shear walls braced frames. Moment frame:

15. floor system Joist system using Vulcraft: Spacing = 2’ o.c. Supports unchanged slab: 3,5” concrete 3” deck Typical bay:

16. floor system Stress analysis The areas to be concerned about were around the elevator core and the openings

17. floor system Moment diagram analysis

18. floor system Encountered problem A suspended stairway transports the visitor to the third floor along the north wall over head

19. floor system Size up the beam The right side beam of the staircase is required to be a W 40 X 183. The columns at the left support of the beam are a W 14X145, and the column at the right support is a W10X45 as shown in the figure below. Analysis in Etabs of the W 40 X 183: Deflection governed The beam is spanning 60 feet, and with the shear walls gone, a W beam less than a W 40 X 183 will deflect more that L/480 = 1.5”

20. Lateral system Changes: Core around elevator Shear walls  braced frames Add columns to replace shear walls Need moment frames around openings

21. Lateral system Core: Braces: W12x96

22. Lateral system New columns in floor plan:

23. Lateral system Bracing –West facade

24. Lateral system Bracing –South facade

25. Lateral system Bracing –East facade

26. Lateral system Type of moment connection: SidePlate™ –Ideally suited against seismic –Up to 25% Reduction in Lateral Frame Tonnage –Up to 50%-65% Reduction in Field Welding Man-Hours

27. Lateral system Moment connection distribution

28. Lateral system ETABS was used to design the lateral force resisting system of the building –IBC 2000 earthquake pressure –ASCE 7-98 wind pressure. Check: –Deflection –Drift  controls

29. Lateral system Lateral drift LevelHeightDispDrift limit (H/400) roof60’0.72”1.8”Pass 3 rd 34’0.48”1.02”Pass 2 nd 18’0.150.54”Pass

30. Vibration Floor vibration Human activities: walking Room: north gallery on 3 rd floor Vibration expectation: small to nonexistent Use design guide 11 from AISC Goal: to understand which system is more adequate for vibration  compare existing/new system

31. Vibration Existing system Composite steel deck

32. Vibration Modified system Joist floor system Both systems have the approximately the same percentage of the acceleration of gravity and are satisfactory to damp vibration while walking in the North gallery of the BAM.

33. Cost comparison

34. Redesigned floor system

35. Cost comparison Existing lateral system

36. Cost comparison

37. Recommendations Disadvantages of Braced Frames: Obstructive interfere with architectural requirements Obstructive interfere with architectural requirements Low Ductility Low Ductility Disadvantages of Moment Frames: Expensive Lots of material plus labor-intensive connections. Expensive Lots of material plus labor-intensive connections. Low Stiffness Low Stiffness Floor system = joist Floor system = joist Less expensive Less expensive Vibration checked Vibration checked decision lateral system = shear walls lateral system = shear walls Less expensive Less expensive Drift checked Drift checked

38. acknowledgments Thank youThank you My AE classmates My friends my family friends & family faculty Prof. Parfitt ۰ Dr. Boothby Dr. Hanagan ۰ Dr. Memari Mr. Tim Bade Mr Ziad Jamaleddine Steven holl architects

39. Questions?