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?