Acterna Headquarters
Germantown, Maryland
John M Sekel
The Pennsylvania State University
Architectural Engineering
2003 Senior Thesis Presentation
Structural Emphasis
Presentation Overview
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Existing Building
Proposal
Structural Redesign
Construction Considerations
Architecture Redesign
Mechanical Considerations
Conclusions and recommendations
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John M Sekel
Existing building
• Project Team
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Owner: Milestone Industrial, LLC
Architect: Hickok, Warner, Fox Architects
Structural Engineer: Structural Design Group
MEP Engineer: Girard Engineering
General Contractor: L.F. Jennings
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Existing Building
• General
– New corporate campus for Acterna
Corporation
– Site clearly visible off I-270 outside
Washington, D.C.
– Six story, 187,500 sf office building
– 253’x126’ building footprint
– $10 million construction cost
– BOCA 1996 design code
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Existing Building
• Structural
– Floor framing
• Composite beam and slab
construction
• 50 ksi wide flange shapes
• 30’x25’ typical bays
• 3 ¼” lightweight concrete slab
on 2” metal decking
• 2 – transfer girders over
conference room on level 1
– Foundations
• Spread footing foundations
• 4” first floor slab on grade
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John M Sekel
Existing Building
• Structural
– Lateral Frames
• 2 – braced frames in each direction
ROOF
SIXTH FLOOR
FIFTH FLOOR
FOURTH FLOOR
THIRD FLOOR
SECOND FLOOR
FIRST FLOOR
FRAME #1
E-W Direction
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FRAME #2
N-S Direction
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FRAME #3
N-S Direction
FRAME #4
E-W Direction
John M Sekel
Existing Building
• Typical framing plan
FRAME #4
FRAME #1
FRAME #2
FRAME #3
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Existing Building
• Mechanical
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VAV boxes with electric duct heaters and reheat coils with VFD
2 – 15000 cfm VAV A/C units per floor
2 – 350 ton cooling towers
Plate and frame heat exchanger
• Electrical/Lighting
– 277/480 volt, 3-phase, 4 wire system
• 4000 amp primary switchboard
• 2000 amp secondary switchboard
– 2’x4’ 277 volt florescent fixtures
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John M Sekel
Presentation Overview
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Existing Building
Proposal
Structural Re-design
Construction Considerations
Architecture Re-design
Mechanical Considerations
Conclusions
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John M Sekel
Proposal
• Structural design goals
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Eliminate intermediate column line outside of core
Use long span steel from core to exterior
Economize the structure
Design for ease of construction
Update to IBC 2000 code
FRAME #4
FRAME #1
FRAME #2
FRAME #3
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Proposal
• Architectural design goals
– Reflect structural changes in
the façade
– Open interior spaces,
column free areas
– Add glazing to lessen “holepunch” look
– Emphasize the drum shape
• Predominant architectural
feature
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Proposal
• Construction goals
– Reduce construction cost
– Reduce construction schedule time
– Design building for ease of construction
• Mechanical considerations
– Analyze impact of façade design on system
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John M Sekel
Presentation Overview
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Existing Building
Proposal
Structural Re-design
Construction Considerations
Architecture Re-design
Mechanical Considerations
Conclusions
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John M Sekel
Structural depth
• Framing Re-design Overview
– New bay size outside of core 30’x50’
– 50 ksi wide flange shapes
• Most readily available shapes
– Possible options
– 3 ¼” lightweight concrete slab on 2” metal deck
• 2 hour fire rating
– Re-size frames for additional gravity load
• IBC 2000 lateral loads
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John M Sekel
Structural depth
• Economic steel design measures
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Redundant shapes
Simple shear tab connections
Efficient spacing and span direction
Efficient bay size
1.5 w
Original
w
1.5 * 25’ = 37.5’
Redesign
1.5 * 30’ = 45’
Use 50’ to maintain core size
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Structural Depth
• New framing plan
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Structural Depth
• New gravity member sizes
– Typical Girders
• Original: W18
• New Design: W24
– Typical Beams
• Original: W14
• New Design: W24
– Typical Interior Column
• Original: W12x65
• New Design: W14x120
– Typical Exterior Column
• Original: W10x54
• New Design: W14x90
– Deflection criteria controls (L/360)
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Structural Depth
ƒn calculation
• Vibration Analysis
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0.18 √[g/(Δg+Δj)]
Typical bay analyzed
Wj=157.8 kips
Δj=1.040”
Wg=156.8 kips
Δg’=0.191”
Po=65 lb
β=0.03
W=157.6 kips
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3.19 Hz
ap/g calculation
[Po e^(-0.35ƒn)]/βW
0.45%g
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Structural Depth
25
• ap/g vs. fn chart
10
– Most accurate between 4
and 8 Hz
– Combined mode frequency
is 3.19 Hz
– Peak acceleration is 0.45%
of g
– Meets acceptable criteria
for office buildings
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Peak Acceleration
(% Gravity)
2.5
1.5
1
Office Buildings
0.5
(3.19, 0.45)
0.25
• 0.64% of g at 3.19 Hz
0.1
0.05
1
3
45
810
25 40
Frequency (Hz)
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Structural Depth
• New Braced Frame Sizes
– Original frame layouts and geometries were maintained
• Frames 1 & 4: Inverted “V”
• Frames 2 & 3: Diagonal
• All web members are TS 10”x10”x5/16”
– Column sizes increased for higher gravity load
– Designed for member strength and drift
• Foundations
– Spread foundation system
– Size and depth increased due to greater load
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John M Sekel
Presentation Overview
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Existing Building
Proposal
Structural Redesign
Construction Considerations
Architecture Redesign
Mechanical Considerations
Conclusions
Structural Option
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Construction Breadth
• Cost Comparison
– RS Means cost estimate for both systems
– Cost includes material, labor and equipment
Item
Original Design
New Design
Difference
Structural Steel
$1,182,852
$1,263,433
$80,581
Fire Proofing
$145,957
$118,316
$28,641
Foundations
$182,790
$159,800
$22,990
Total
$1,511,599
$1,541,549
$28,950
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Construction Breadth
• Schedule Comparison
– Fewer beams to place
• Typical floor original: 222 members
• Typical floor redesign: 127 members
– Fewer columns and foundations
• 16 columns removed in redesign
– 30% reduction in structure construction time
Original Design
Redesign
20 days foundations
14 days foundations
9 weeks superstructure
6 ½ weeks superstructure
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John M Sekel
Presentation Overview
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Existing Building
Proposal
Structural Redesign
Construction Considerations
Architecture Redesign
Mechanical Considerations
Conclusions
Structural Option
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Architectural Breadth
• Reflect change in floor framing
Square
box-like
windows
Structural Option
Long,
continuous
windows
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Architectural Breadth
• Increase glazing
• Emphasize the drum
– Vertically spanning glass
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John M Sekel
Architectural Breadth
Structural Option
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John M Sekel
Architectural Breadth
Structural Option
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Architectural Breadth
Structural Option
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John M Sekel
Architectural Breadth
Structural Option
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Presentation Overview
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Existing Building
Proposal
Structural Redesign
Construction Considerations
Architecture Redesign
Mechanical Considerations
Conclusions
Structural Option
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Mechanical Breadth
• Increase in cooling load
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Greater glazing area on facade
Carrier hourly analysis program analysis
Additional 1.5 tons of cooling required per floor
Original system capacity is 92 tons per floor
1.6% increase
• Most likely will not need to resize equipment
– Further analysis required
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Presentation Overview
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Existing Building
Proposal
Structural Redesign
Construction Considerations
Architecture Redesign
Mechanical Considerations
Conclusions
Structural Option
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John M Sekel
Conclusions
• Insignificant cost difference by implementing new system
• Shorter construction time
– Faster cost return
• Improvement to building architecture
– Greater tenant flexibility with interior spaces
• Good selling point for owner
– More notable exterior façade
Final Recommendation:
Use re-designed structural system
Structural Option
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John M Sekel
Thank You
• Structural Design Group
– Mike Weiss
• LF Jennings
– Kevin Malpass
• AE Faculty and staff
– Prof. Parfitt, Dr. Geschwinder, Dr. Hanagan
• AE classmates
– Chris Flynn, Tim Nolan
• My parents and roommates for their encouragement and
support
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Questions?
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?
Structural Option
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Structural Depth
• Building Height Comparison
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Structural Depth
• Plenum heights
– 11 ¾” increase per
floor
– 5’-10 ½” total
building height
increase
514"
514"
W30
W18
2'-5"
3'-1043"
4'-1012"
2'-5"
14'-343"
13'-4"
9'
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9'
John M Sekel
Structural depth
• Plenum comparison
Typical In-Bay
Framing Member
Deepest Member
at Duct Crossing
Required Plenum
Depth
Original Design
W14x22 [17] 1”
W18
46 ¾”
New Design
W24x55 [48] 1 ¼”
W30
58 ½”
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Structural Depth
• Deflections and camber
3"
116
4" 2"
514"
5"
W Shape
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Structural Depth
• Connections
W14x22
Full fillet
weld both
sides (typ.)
(4) A 325
7/8" bolts
Shear tab
2.80"
10.39"
W24x62
W24x62
W14x120
W24x55
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Structural Depth
• Drift
Structural Option
Frame
Drift
Ratio
#1
1.77”
1/583
#2
1.49”
1/693
#3
1.44”
1/717
#4
2.43”
1/425
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John M Sekel
Structural Depth
• Drift
Frame #1
Frame #2
Frame #3
Frame #4
Level
Drift
Ratio
Drift
Ratio
Drift
Ratio
Drift
Ratio
2
0.290”
1/662
0.219”
1/877
0.226”
1/850
0.371”
1/518
3
0.288”
1/583
0.268”
1/627
0.270”
1/622
0.386”
1/435
4
0.299”
1/562
0.265”
1/634
0.260”
1/646
0.414”
1/406
5
0.295”
1/570
0.254”
1/661
0.244”
1/689
0.415”
1/405
6
0.292”
1/575
0.240”
1/700
0.224”
1/750
0.411”
1/409
R
0.302”
1/616
0.238”
1/782
0.212”
1/877
0.430”
1/433
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Construction Breadth
• Working crews
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RS Means assumes a steel crew of the following:
(2) Steel foremen
(5) Steel workers
(1) Welder
(1) Welding machine
(1) Oiler operator
(1) Crane operator
(1) 90 ton crane
The daily operating cost for this crew is $4091.40.
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Construction Breadth
• Crane reach
– 60 ton crane
– 4 ton pick at 60’
– W21X182 frame
column
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Construction Breadth
• Project delivery system
OWNER
Contract Line
Milestone Industrial, LLC
Conversation Line
FIXED
PRICE
FIXED
PRICE
CIVIL
ENGINEER
FIXED
PRICE
ARCHITECT
GENERAL
CONTRACTOR
Hickok Warner Fox Architects
L.F. Jennings
FIXED
PRICE
STRUCTURAL
ENGINEER
MEP
ENGINEER
Structural Design Group, Ltd.
Girard Engineering, Ltd.
FIXED
PRICE
COST PLUS
FEE
STEEL
CONTRACTOR
LUMP SUM
LUMP SUM
LOBBY
CONTRACTOR
COST PLUS
FEE
LUMP SUM
MECHANICAL
CONTRACTOR
OTHER
ENGINEERS
Structural Option
COST PLUS
FEE
GMP
ELECTRICAL
CONTRACTOR
STEEL
ERECTOR
OTHER
CONTRACTORS
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Construction Breadth
• Linear footage comparison
– Original structure: 43,300 feet
– Redesigned structure: 32,700 feet
– Additional cost is hidden in fabrication and materials
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