overlook towers at dulles corner herndon, virginia anthony perrotta ae senior thesis – structural...
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OVERLOOK TOWERS AT DULLES CORNERHERNDON, VIRGINIA
Anthony Perrotta
AE Senior Thesis – Structural Option
Outline
Primary Project TeamProject Overview
ArchitecturalExisting Floor
SystemExisting Lateral
SystemStructural Re-designFloor SystemGravity SystemLateral System
Loading Conditions
Construction ManagementProposed Structural
CostProposed Schedule
Primary Project Team
Owner: S. Vardell Realty Investments, L.L.C.
Architect: Noritake Associates
Landscape Architect: Lewis Scully Gionet
Structural Engineer: Haynes Whaley Associates
M.E.P. : KTA Group Inc.
Civil Engineer: William H. Gordon Associates
CM: Clark Construction
Overlook Towers at Dulles Corner
Herndon, VA
Building Overview & Existing Conditions
Building LocationOverlook Towers at Dulles Corner2550 Waser TerraceHerndon, Virginia
Building Summary
3 Building Complex
Sept. 2006 – December 2007
$ 20.5 million
262,000 s.f.
190,000 s.f.
Project Timeframe:
Building Design219’ x 125’24,000 s.f. per floor13’-6” typical floor height
Building Design
219’-2”
219’ x 125’24,000 s.f. per floor13’-6” typical floor height
Building Design
219’-2”
125’
219’ x 125’24,000 s.f. per floor13’-6” typical floor height
Building Design
Building Design
21,000 s.f. of Office Space
Existing Floor System
Foundation:
Elevated Slab:
Spread footings & Grade Beams4” thick 4,000 psi SOG10 mil vapor barrier4” compacted granular stone
Framing Plan
Typical BayExterior: 30’-0” x 46’-0”Interior: 30’-0” x 30’-0”W24x55 (typical beam size)
Controlling Size: 30’-0” x 46’-0” Exterior Bay
12’-6” o.c. Beam Spacing
Design Loads (IBC 2000): Office Space: 100 psf Corridors: 100 psf Mechanical: 125 psf Dead: 25 psf superimposed
Lateral System
4 Steel Braced Frames
Located around Central Core
Design Loads
Gravity Loads Live LoadsMechanical & Ceiling
5 PSF Roof Snow Load 30 PSF
Single Ply Roof 11 PSF Office Space 100 PSFFinishes As
RequiredPermanent Corridors 100 PSF
Sprinkler System As Required
Lobbies & Stairs 100 PSF
Mechanical Space* 125 PSF
IBC 2000:
ASCE7-05:Wind Loading Seismic Loading
Wind Speed 90 mph Seismic Use Group
I
Importance Factor
1.0 Importance Factor
1.0
Wind Exposure B Design Category
B
Enclosure Class.
0.18
Design Loads
Wind Loading (N-S): Seismic (N-S):
Depth Analysis
Alternate Structural System
Design Goals
Find Alternate Structural System to:Decrease overall cost of the structural system.
Decrease overall construction time.
Proposed Floor System
Precast Double-T Slab
15LDT26
Typical span of 46 feet.
Designed to carry a load of 120 psf.
Dead Load: 57 psf.
< 126 psf
19% Lighter
Proposed Floor System
Precast IT & L-BEAM
30’ & 46’ Exterior Spans
30’ Interior Spans
Dead Load: 800 plf6.7 klf < 7.1 klf
Dead Load: 625 plf4.1 klf < 5.2 klf
Much heavier than W-shapes.
Precast Framing Plan
Lateral System
Lateral System
1 2 3 4
Does not disturb architectural design of building.
Cheap and efficient design.
No downtime from concrete curing.
Lateral System highlighted
Structural Model
Breadth Analysis
Construction Management
Project Schedule
Common Start: 10/02/07
Avg. Floor Completion: 26 days
End Structural Construction 3/22/07
10/02/07
16 days
3/14/07
Existing Proposed
6 Days Earlier
Project Schedule
Existing:
Proposed:
Project Estimate
Key Costs Elev. Slab: $
1.01million Steel: $ 2.4 million Fireproofing:
$182,000
Overall Structural Cost $4 million
Key Costs Double-T: $1.4
million Beams: $1.2 million Fireproofing:
$65,000
$3.6 million
Existing Proposed
Possible Savings of $ 400,000
Summary
Building Weight:
Construction Schedule:
Building Cost:
~ 4.1 % Lighter
Less 6 days
Possible 10% Savings
Existing Proposed
Summary
Building Weight:
Construction Schedule:
Building Cost:
~ 4.1 % Lighter
Less 6 days
Possible 10% Savings
Existing Proposed
Questions?