Nijad Rudy Boukhalil structural option spring

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Nijad Rudy Boukhalilstructural optionspring05
                                              
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Presentation outline

• Project background
• Existing conditions
• Problem statement
• Proposed solution
• Floor system
• Lateral system
• vibration
• Construction management
• Recommendations
• Acknowledgements
• questions

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Project background

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

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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

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Project background

• Project team
• general contractor Sellen construction Co.
• mechanical design/build contractor Mckinstry
  Co.
• design architect Steven Holl architects
• Associate ArchitectSclater Partners Architects
• structural engineer Skiling Ward Magnusson
  barkshire, inc

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Project background

• Architectural layout
• 3 galleries
• 3 light qualities
• 3 actions - see/explore/make (art, science,
  technology)
• 3 main levels
• 3 circulation directions

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Existing conditions

• Floor system
• Composite steel deck
• 3.5 concrete
• normal weight concrete
• compression strength fc 4000 psi
• 3 metal deck
• shear studs
• Advantages
• Good with Long span
• efficient and economic
• Good strength to weight ratio
• Smaller foundation needed

• Disadvantages
• Crane demanding
• Difficult coordination
• vibration

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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
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Existing conditions

• Seismic Load Calculations (ASCE 7-02)
• Assumptions
• Occupancy Category III
• Seismic Use Group II
• Site Class D
• Seismic response coefficient R6

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Problem statement

• Seismic hazard effect
• Half of the states
• 109 million people
• 4.3 million businesses
• More frequent vibration ? key issue for a museum
• Original system
• Floor system Composite floor
• Lightweight system ? more subjected to vibration
• Lateral system Shear walls
• Good choice against earthquakes

• Earthquake Cost damage
• Direct cost 1 billion/year
• indirect business losses 2 billion/year

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Proposed solutions

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

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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

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Proposed solution

• Different types of bracings
• Single Diagonals
• has to resist tension and compression caused by
  sideways forces in both directions on a frame.
• Cross Bracing
• only need to resist tension
• 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.
• This is the most widely used type of bracing
  system.

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Proposed solution
Moment frame

• Why moment frames ok
• Obstructions rejected
• eliminates space limitations of solid shear walls
  braced frames.

• Advantages
• Allows for windows in walls, and other open
  spaces

• Disadvantages
• Large deflections
• Larger Members
• Cost increase

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floor system

• Joist system using Vulcraft
• Spacing 2 o.c.
• Supports unchanged slab
• 3,5 concrete
• 3 deck
• Typical bay

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floor system

• Stress analysis
• The areas to be concerned about were around the
  elevator core and the openings

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floor system

• Moment diagram analysis

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floor system

• Encountered problem

• A suspended stairway transports the visitor to
  the third floor along the north wall over head

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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

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Lateral system

• Changes
• Core around elevator
• Shear walls ? braced frames
• Add columns to replace shear walls
• Need moment frames around openings

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Lateral system

• Core
• Braces W12x96

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Lateral system

• New columns in floor plan

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Lateral system

• Bracing
• West facade

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Lateral system

• Bracing
• South facade

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Lateral system

• Bracing
• East facade

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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

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Lateral system
Moment connection distribution
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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

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Lateral system

• Lateral drift

Level Height Disp Drift limit (H/400)
roof 60 0.72 1.8 Pass
3rd 34 0.48 1.02 Pass
2nd 18 0.15 0.54 Pass
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Vibration

• Floor vibration
• Human activities walking
• Room north gallery on 3rd 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

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Vibration

• Existing system
• Composite steel deck

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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.
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Cost comparison
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Cost comparison

• Redesigned floor system

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Cost comparison

• Existing lateral system

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Cost comparison
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Recommendations

• Disadvantages of Braced Frames
• Obstructiveinterfere with architectural
  requirements
• Low Ductility
• Disadvantages of Moment Frames
• ExpensiveLots of material plus labor-intensive
  connections.
• Low Stiffness

decision

• Floor system joist
• Less expensive
• Vibration checked

• lateral system shear walls
• Less expensive
• Drift checked

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acknowledgments

• Thank you

faculty
Steven holl architects
Prof. Parfitt ? Dr. Boothby Dr. Hanagan ? Dr.
Memari
Mr. Tim Bade Mr Ziad Jamaleddine
friends family
My AE classmates My friends my family
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Questions?