discovery communications headquarters silver springs, md josh woolcock structural option...
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Discovery CommunicationsHeadquartersSilver Springs, MD
Josh WoolcockStructural
Option
Architectural EngineeringPennsylvania State University
Outline
- Building Information
- Existing Conditions
- Structural Analysis
- Cost Analysis
- Schedule Analysis
- Office Lighting Design
- Conclusions
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Project Team
Owner Discovery Communications Inc.
Architect SmithGroup Inc.
Engineers Structural – KTLH Engineering Civil – VIKA Inc. MEP – Flack & Kurtz
General Contractor Clark Construction
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Building Overview
- Multipurpose Office Facility- two independent towers, of 7 and 10-stories
- 3 levels of underground parking
- 550,000 sqft. of open office space
- $52 Million overall cost
Layout & Function
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Existing ConditionsMechanical
-Individual air-handling units on each floor
-Duct work for tenant build-out
- 3 centrifugal water chillers and roof cooling towers
- 3 gas-fired furnaces
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Existing ConditionsLighting / Electrical
- Three 4,000A three-phase feeders for three switchboards, totaling 12,000A
- Lighting in office space reserved for tenant build-out
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Existing ConditionsStructural
- CIP Concrete Structural System
- Two structurally independent towers
- 2-way cambered 9” structural slab with drop panels
-30’ x 30’ column grid
-Column sizes up to 36” x 48”
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural Analysis
PurposeTo reduce the size of the columns within the office spaces to reduce concrete volume, increase floor space and promote aesthetics.
Reasons for Initial Size- Act as both lateral and gravity system- Building sway constraints- Large dead Loads
Possible Solutions- Separation of Lateral and Gravity Systems- Reduction of Gravity Loads
FocusNorth Tower: 10 Office Floors & Penthouse
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisInitial Considerations
-Loads calculated from IBC2000-Deflection Requirements
-H/400 for service wind loads-H/50 for service seismic loads-Respect to other tower: Contact at 8th Floor
-Building Geometry-Much longer than it is wide
-Secondary Considerations-Building Floor Plan and Impact-Impact on other building systems
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisFloor Slab Reduction
-ADOSS was used: Equivalent Frame Method
-Floor slab construction switched from 4000psi to 5000psi concrete
-Slab thickness reduced from 9” to 8”
-Drop panels remain 7.5”
-Slab Reinforcement increased from an average of 4.46psf to 4.89psf
-Maximum D+L deflection is 0.759”
-Slab weight was reduced by 11% or 11.25kip per column per floor
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisShear Walls
-4 preliminary locations for shear walls
-Locations do no hinder original floor plan
-Tests were performed to determine their lateral performance
-Use of 4 walls resulted in excess torsion
-2 shear walls were implemented and located to reduce torsion in building
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisShear Wall Design
-Walls Start at floor 1 and continue to main roof
-Walls span column-to-column
-Design changes at floors 1,3,5 & 7
-Maximum loads – Wind w/ Torsion & Factored
- 765.3 kip Shear
- 57269.81ft-kip Bending
-1909 kip Axial
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisShear Wall Design
-24” x 36” columns at ends
- Concrete strength
- 10000psi at Floor 1
- 8000psi at Floor 3
- 4000psi at floor 5
-Wall Reinforcement
- #5@18” Horz.
- #5@18” Vert.
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisShear Transfer
-Shear Walls stop at first floor
-Columns continue down to foundation
-No Bending in Slab
- Shear transferred from walls to floor slab then to retaining walls
- Lateral earth pressure resists shear and locks floor 1 in place
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisColumn Reduction
-All Columns within office spaces are 24” x 24”
-4 different column designs
-Concrete Strengths
- 8000psi Floor 1
- 6000psi Floor 3
- 4000psi Floor 5
- 4000psi Floor 7
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisFinal Lateral System
- North-South Direction
- Combination of Shear walls and Moment Frames
- Contribution via stiffness analysis
- 66.8% Shear walls at floor 10
- 90.1% Shear walls at floor 5
- 96.3% Shear walls at Floor 1
- East-West Direction
-Moment Frames
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisLateral System Performance
- North-South Direction
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
-East-West Direction
LATERAL DISPLACEMENTS - NS DIRECTION
F1 S1 S2 F14Roof 1.04 1.25 1.3 1.66
8 0.78 0.93 0.96 1.23Roof -0.54 1.14 1.47 3.6
8 -0.4 0.84 1.09 2.66Roof 1.4 1.39 1.38 1.37
8 1.04 1.03 1.02 1.01Roof -0.46 1.27 1.61 3.43
8 -0.34 0.94 1.19 2.54Seismic w/ Torsion
Load Condition LocationDiflection
Wind
Wind w/ Torsion
Sesimic
LATERAL DISPLACEMENTS - EW DIRECTION
F-A F-B F-C F-D F-ERoof 2.09 2.15 2.27 2.40 2.52
8 1.53 1.57 1.66 1.75 1.84Roof 1.56 1.76 2.07 2.70 3.18
8 1.14 1.28 1.51 1.97 2.32Roof 4.34 4.42 4.58 4.90 5.14
8 3.17 3.23 3.34 3.58 3.75Roof 3.55 3.84 4.33 5.33 6.08
8 2.59 2.80 3.16 3.89 4.44Seismic w/ Torsion
Load Condition LocationDiflection
Wind
Wind w/ Torsion
Sesimic
Notes:
Max Wind = 2.66”
Max Seismic = 2.54”
Notes:
Max Wind = 2.32”
Max Seismic = 4.44”
Structural AnalysisConclusions
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
-Reduction in floor slab produced a 11% decrease in slab dead load on columns
-Implementation of Shear Walls reduced bending stresses in columns due to lateral forces
-Column size was reduced to 24”x24” throughout the office spaces
- Placement of Shear Walls did not adversely affect building floor plan or mechanical and fire protection services
Cost AnalysisInitial Considerations
- Detailed Estimate performed on both original and new structural systems
- Costs Estimated using RSMeans 2001
- Bare Costs : Overhead and Profit not included
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Purpose Determine cost implications of new structural systems
EXISTING SYSTEM
Work Item U/M Quantity Cost $ / Unit Total Cost $
Total Concrete cy 2765.44000 psi cy 2012.9 65 $130,838.506000 psi cy 752.5 78.85 $59,334.638000 psi cy 0 128.2 $0.00
Reinforcing ton 188.5 935.75 $176,388.88Concrete Placement cy 2765.4 20.83 $57,603.28Formwork sqft 112000 3.92 $439,040.00
Total $863,205.28
Cost AnalysisColumns
REDESIGNED SYSTEM
Work Item U/M Quantity Cost $ / Unit Total Cost $
Total Concrete cy 1555.54000 psi cy 977.3 65 $63,524.506000 psi cy 254.1 78.85 $20,035.798000 psi cy 324.1 128.2 $41,549.62
Reinforcing ton 215.46 935.75 $201,616.70Concrete Placement cy 1555.5 23.08 $35,900.94Formwork sqft 84000 4.09 $343,560.00
Total $706,187.54
Notes:
- 43.8% Reduction in volume (1210cy)
- 25% Reduction in formwork (28000sqft)
- 14.3% increase in reinforcement
- Cost Savings of $157,017.74
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
EXISTING SYSTEM
Work Item U/M Quantity Cost $ / Unit Total Cost $
Total Concrete cy 11340.34000 psi cy 11340.3 65 $737,119.505000 psi cy 0 69.35 $0.00
Reinforcing ton 927 897.75 $832,214.25Concrete Placement cy 11340.3 13.25 $150,258.98Formwork sqft 408250 3.74 $1,526,855.00
Total $3,246,447.73
Cost AnalysisFloor Slab
Notes:
- 1” reduction in slab thickness
- 11.1% Reduction in volume (1260cy)
- 7.2% increase in reinforcement
- Increased Cost of $5,493.33
REDESIGNED SYSTEM
Work Item U/M Quantity Cost $ / Unit Total Cost $
Total Concrete cy 10080.24000 psi cy 0 65 $0.005000 psi cy 10080.3 69.35 $699,068.81
Reinforcing ton 994.1 897.75 $892,453.28Concrete Placement cy 10080.3 13.25 $133,563.98Formwork sqft 408250 3.74 $1,526,855.00
Total $3,251,941.06
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Cost AnalysisShear Walls
REDESIGNED SYSTEM
Work Item U/M Quantity Cost $ / Unit Total Cost $
Total Concrete cy 291.334000 psi cy 165.22 65 $10,739.308000 psi cy 54.44 78.85 $4,292.5910000 psi cy 71.67 179.89 $12,892.72
Reinforcing ton 12.6 831.25 $10,473.75Concrete Placement cy 333.33 13.92 $4,639.95Formwork sqft 14683.2 2.63 $38,616.82
Total $81,655.13
Notes:
-291.33cy of additional concrete
-14,683.2 sqft of formwork
-12.6 ton of additional reinforcement
-Approximately $81,700 in additional cost
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Cost AnalysisConclusions
Notes:
-2178.67 cy reduction in concrete
-14,366 sqft reduction in formwork
-106.66 ton increase in reinforcement
-Cost savings of nearly $70,000.00
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
REDESIGNED SYSTEM
Systems Total Cost $
Floor Slabs $5,493.33Shear Walls $81,655.13Columns -$157,017.74
Cost Difference -$69,869.28
Schedule AnalysisInitial Considerations
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
- Possible construction sequence for the original and new system
- Based on a 2 week floor to floor construction time
- Production number calculated from 2001 edition of RSMeans
- Slab pours would be made every 2 days to facilitate construction of both towers simultaneously
Purpose Analyze construction time and sequencing of new structural
system via floor to floor erection time
Schedule AnalysisProduction
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
- Production capacity-1 crew can erect 3 columns / day-1 crew can erect 1 shear wall / 2 days
CREW PRODUCTIONCrew Task Unit QuantityC-7 Slab Concrete cy 110
Column Concrete cy 70Shear Wall Concret cy 90
4 Rodmen Slab Rebar ton 3Column Rebar ton 2.3Shear Wall Rebar ton 3
C-2 Slab Forms sf 560C-1 Columns Forms sf 240
Shear Walls Forms sf 790
Schedule AnalysisOriginal System
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
-Columns- 2 Form crews- 1 Rebar crew- 1 Concrete crew
-Elevated Slab-4 Form Crews-3 Rebar Crews-2 Concrete Crews
-70 Columns in 10 days-2.3 crews needed
Schedule AnalysisNew System
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
-Columns / Shear Wall- 3 Form crews- 1 Rebar crew- 1 Concrete crew
-Elevated Slab-4 Form Crews-3 Rebar Crews-2 Concrete Crews
-70 Columns & 2 Shear Walls in 10 days-Equivalent to 82 Columns
-2.73 crews needed
Schedule AnalysisConclusions
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
- Both systems require same crews for elevated slab work
- New structural system requires 1 additional crew for columns / shear walls
Office LightingInitial Considerations
-Ceiling height is approximately 11’-8”
-No finished ceiling
-Exposed underside of concrete slab
-Exposed Mechanical 18” Deep
-Spaces used primarily used for office work
-Requires Approximately 50fc or 500lx on the work plane
-Best choice for these requirements is an indirect lighting system
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Purpose Design a general lighting system for the open office spaces
Office LightingDesign
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
-Due to exposed mechanical systems and no finished ceiling, indirect lighting would not work well
-Decision to incorporate reflector panels was made
-Provide ideal surface for reflected light
-Hang 24” from ceiling
-Able to provide access to exposed mechanical and fire protection services
Office LightingResults
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
-Model was created using Lightscape
-Peerless LDX030452 was selected
- Uses (3) 32W T8 lamps
- Input Wattage of 113W
-Produced approximately 510lx on work plane
-Power density of 0.715 W/sqft
Office LightingRenderings
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Conclusions & Recommendations
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
- Floor slabs were reduced from 9” to 8” resulting in an 11% reduction in dead load
- Implementation of shear walls reduced bending stresses in columns
- Column size reduced to 24”x24”
-43.8% reduction in volume
-2200 sqft of additional floor space
- New design results in a savings of $70,000
- No change in floor cycle time
- Lighting design provides an efficient and aesthetic pleasing system for the general office spaces
Acknowledgements
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Thank You to the following….- Discovery Communications Inc.
- Clark Construction Inc. with special consideration to
Ray Sowers
George Conard
Ken Alexander
- The entire AE Faculty with special consideration to
Dr. Lewis Geschwindner
Dr. Thomas Boothby
Dr. Linda Hanagan
- My Family
- My Friends in and out of Architectural Engineering
Questions
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
- Silver Springs, MD
- Intersections of Georgia Avenue and Colesville Road
- Approximately 8 miles from downtown Washington D.C.
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Location
Building Overview
- Multipurpose Office Facility- two independent towers, of 7 and 10-stories- 3 levels of underground parking- 550,000 sqft. of open office space- $52 Million overall cost
Layout & Function
Architecture- Aluminum and Glass curtain wall system-12-story glass atrium connects the two building- Rooftop Terrace and Garden
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural AnalysisShear Walls
- No impact on existing mechanical and Fire Protection Services
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Structural Analysis3D Analysis
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
LATERAL DISPLACEMENTS - 3D MODEL
X Y X Y X Y X Y
Roof 0.186 -0.775 0.186 -1.967 -0.172 -0.775 -0.172 -1.967
8 0.168 -0.764 0.186 -1.865 -0.162 -0.765 -0.162 -1.865
Roof 4.94 0.23 4.94 -0.163 2.82 0.23 2.82 -0.163
8 3.644 0.214 3.644 -0.155 2.594 0.214 2.594 -0.155
Diflection (in)
NE NW SE SW
Seismic w/ Torsion EW
Load Condition Location
Wind w/ Torsion NS
Direction
Breadth Aspects
Lateral System Cost Analysis Determine cost implications of new structural systems
Lateral System Schedule Analysis Analyze construction time and sequencing of new structural
system via floor to floor erection time
Pennsylvania State UniversityArchitectural Engineering
Josh WoolcockStructural Option
Office Lighting Design Design a general lighting system for the open office spaces
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