milton s. hershey medical center biomedical research building joshua zolko, structural option
TRANSCRIPT
Milton S. Hershey Medical Center Biomedical Research Building
Joshua Zolko, Structural Option
Introduction• The Biomedical Research Building (BMR)
is located in Hershey, Pennsylvania.• 245000 sq. ft, in 7 stories above grade• Built between 1991-1993• Cost $49 million• Used a Bid-Build project delivery method• Used for Education and Laboratory space
Table of Contents• Introduction• Architecture• Existing Structure• Process• Cost Comparison• Conclusion
Introduction• Site soil is considered poor, and as such,
columns were designed as pinned at the bottom.• Goal of this proposal is to determine if a
steel structure is more cost effective than a concrete structure.
Table of Contents• Introduction• Architecture• Existing Structure• Process• Cost Comparison• Conclusion
Architecture• Façade of the BMR consists of long
horizontal concrete and limestone slabs, and black glazing• Façade designed to relate to buildings
already existing on campus• Cylinder and Planar wall on corners add
to the otherwise flat building
Table of Contents• Introduction• Architecture• Existing Structure• Process• Cost Comparison• Conclusion
Existing Structure• The BMR is a monolithic concrete
structure, using a two-way flat plate system with the average column size about 22” by 22”• Building sits on a deep foundation
system of caissons 3 to 7 feet in diameter
Table of Contents• Introduction• Architecture• Existing Structure• Process• Cost Comparison• Conclusion
Process• Assumed gravity loads were to be:• 45 PSF dead• 40 PSF snow• 20 PSF superimposed• 125 PSF live core, 100 PSF live offices
Typical Floor PlanTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Process• Dead Load is from 3.5” slab (t = 3”) using
1.0CSV Conform decking from Vulcraft assuming 5’ joist spacing.• Gives 45 psf, plus 20 psf superimposed
for 65 psf dead.
Preliminary LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Process• Using 1.2D + 1.6L, loading is 278 PSF
core.• Loading for joist is 1.4 KLF with 5’
tributary width.• Requires a W14x22 joist size.• Deflection under this loading is .63”,
satisfying L/360.
Preliminary LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Process• Beam loading with a tributary width of
21’ is 5.8klf.• Braced at every 5’, under this load,
requires a w12x120.• Beams deflects .47”, satisfying L/360.
Preliminary LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Process• Gravity columns have a tributary area of
21’ by 33’. Total of 693 sq ft.• Due to the large live load, live load
reduction does not apply to members supporting only one floor, and those that do, maximum of 20% reduction.
Preliminary LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Process• Axial load per floor is 192.7 Kips.• After LLR, load is 165 kips.• With alternate loading of bays, and axial
loads, gravity column sizes range from W14x90 to W14x159.
Gravity Column ShapesTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Story Shape7 w14x906 w14x995 w14x1094 w14x1203 w14x1452 w14x1451 w14x159
Process• Analysis was repeated for the office
spaces, and no changes were made.• Column sizes were the same aside from
the third story where a reduction to a W14x132 could have been made, but it was decide to keep it uniform with the core.
Preliminary LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity
• Cost Comparison• Conclusion
Process• Goal of Lateral Design was to keep the
drift of the building under 2.6”, or H/400, with H = 88’• Hall/office spaces to have minimal drift
as they attach to an adjacent building.
Initial LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Initial Lateral design consisted of only
Moment Frames.• Frames were assumed to be equally stiff,
and checked via RAM.• Equal stiffness allowed for individual
frame design.
Initial LayoutTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Using ASCE 7-10, Wind loads were
derived.• Loads were then divided amongst the
moment frames.• Portal method was used to estimate
loads.
Wind LoadsTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Y (Kips) X (Kips)7 37.7 23.16 36.1 22.25 34.1 21.04 32.6 20.03 29.8 18.32 27.4 16.81 24.8 15.2
Process• Loads from both lateral and gravity
forces were combined using interaction equations, including biaxial forces from overlapping lateral frames.• Drifts from the initial design were too
high, and frames were rearranged, and braced frames were added.
Final Frame DesignTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Loads from both lateral and gravity
forces were combined using interaction equations, including biaxial forces from overlapping lateral frames.• Drifts from the initial design were too
high, and frames were rearranged, and braced frames were added.
Biaxial Lateral ColumnsTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Braced Frames were designed in order to
decrease the drift caused by torsion.• A specific rigidity was found in order to
move the center of rigidity to the center of mass, and braces were sized in order to acquire this rigidity in order to decrease torsional effects.
Braced FrameTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Story Shape7 HSS6.625X0.2506 HSS6.625X0.2505 HSS7.0X0.2504 HSS7.5X0.2503 HSS8.625X0.2502 HSS8.625X0.3221 HSS9.625xX.250
Process• Problem with this braced frame being
placed at the north side, is that the braced frame will be placed directly in front of the glazing.
Braced FrameTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Story Shape7 HSS6.625X0.2506 HSS6.625X0.2505 HSS7.0X0.2504 HSS7.5X0.2503 HSS8.625X0.2502 HSS8.625X0.3221 HSS9.625xX.250
Process• Loads from both lateral and gravity
forces were combined using interaction equations, including biaxial forces from overlapping lateral frames.• Drifts from the initial design were too
high, and frames were rearranged, and braced frames were added.
Braced FrameTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Braced Frames were placed in order to
not block entrances into maintenance shafts• Halls go through center bay
Braced FrameTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Overturning was checked, and was not
an issue in either direction under controlling loads of either wind or seismic.
Overturning TablesTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Process• Braced Frames were placed in order to
not block entrances into maintenance shafts• Halls go through center bay
Final Frame DesignTable of Contents• Introduction• Architecture• Existing Structure• Process• Gravity• Lateral
• Cost Comparison• Conclusion
Cost Comparison
• Original Plan costs $49 million• Proposal costs $.... million
CalculationsTable of Contents
• Introduction• Architecture• Structure• Process• Cost Comparison• Conclusion