Owner:

Tishman Speyer Properties
http://tishmanspeyer.com/

Architect:

Hellmuth, Obata + Kassabaum, P.C.
http://www.hok.com/

General Contractor:

James G. DAVIS Construction Corporation http://www.davisconstruction.com/

MEP Contractor:

GHT Limited
http://www.ghtltd.com/

Structural Contractor:

Smislova, Kehnemui & Associates, P.C.
http://www.skaengineers.com/

Civil Engineer:

VIKA, Inc.
http://www.vika.com/

Schedule:

Original Schedule was Feburary 2006 to March 2007
Notice To Proceed came March 2006
With a schedule of 13 months the buildings were to be completed by mid April 2007 for building one and mid May 2007 for building two.

Cost: $28,000,000

Project Delivery Method: Design-Bid-Build project

Architecture

Design and Function:

These office buildings are two of the same. Mirroring each other on a ninety degree angle these rectangular shaped buildings have precast concrete slabs and windows covering the exterior wall. Each floor has large windows interrupted by concrete columns and rows running up and along the building. Except for half of the fifth floor, which has a horizontal display of glass only separated by mullions then covered by the precast towards the roof. The first floor has a large lobby which extends through the entire building. The lobby leads to the core of the office building which houses the elevators. Two stair cases are located in the center of each side of the building. Other than the lobby, the first floor along with each other floor is open for the tenant to place walls wherever they please.

Major National Model:

The original building was designed in 1999 which was designed using a 1997 or 1998 code. Drawings were updated in a bid set which used IBC 2000. The electrical and mechanical were updated later. Specific to Fairfax County there was a Special Inspections: Implementation in Fairfax County - 2000 Edition (Effective: October 1, 2003) book, which was followed for code compliance and inspection procedures based on the Virginia Uniform Statewide Building Code (2000) Edition, 13 VAC 5-62-10 et. seq., effective October 1, 2003.

Building Envelope:

The entire facade of the building is a curtain wall consisting of precast concrete, mullions, and large panes of vision and spandrel glass. There is a large wall protruding from each side of the building and above but not connecting across the roof, almost making the appearance that the building is sectioned into two. This wall is covered by precast concrete sections and is completely for show. The roof houses a large mechanical screen wall to block view of any mechanical and elevator equipment rooms. The roof is built up above a concrete slab with insulation followed by a topping of gravel. The mechanical system runs from the roof down through building by ducts and cutouts in the slabs.

Building Systems

Structural Cast in Place Concrete:

The entire structure of the building was made of Cast in Place, post tensioned concrete, 80 lb./sq.ft. live load, 20 lb./sq.ft. partition load capacity. The foundation used spread footings while the rest of the building included cast in place columns and slabs. The slabs also included post tensioned beams across the main columns. There was a mixture of short and long span areas over each floor slab with bays ranging from 45’ X 20’ at the perimeter and 27’ X 20’ typical interior bay. The roof was a hot - applied rubberized asphalt system with a 15-year system warranty. Crane and bucket was the typical pouring method for the foundation and columns. A pump truck was used for each floor. Using both methods helped with time and efficiency. The slab on grade was a 5” thick, 3,500 psi normal weight concrete, reinforced with 6x6-W1.4xW1.4 welded wire fabric on 6 mil. Polyethylene sheet over 6” wash crushed stone. Each additional floor slab was post-tensioned beam and non-post-tensioned one-way slab construction with 4,000 psi normal weight concrete with 7” thick slabs. Each was reinforced as shown on each structural floor plan. Concrete canopies only occur at second floor level.

Precast Concrete / Curtain Wall:

Precast concrete was used for the curtain wall and the stairs throughout the building. The precast concrete panels were connected through embeds placed in the cast in place concrete slabs and columns. The precast panels were made in Canada and driven down to the jobsite on tractor trailers. The curtain wall façade consisted of precast architectural spandrel panels and column covers with mullions, vision and spandrel glass; 1-inch thin slat Venetian blinds provided for perimeter windows. The curtain wall windows were designed by Arctec Precision Glazing and tested at ATI in York, PA.

Mechanical System:

Each typical floor has a 90-ton A/C unit capable of providing the equivalent capacity ratio of one ton for each 254 sq. ft of usable floor area. There are approximately 17 fan powered VAV boxes with re-heat coils and 8 cooling only VAV boxes to provide sufficient conditioned air to each floor. The self contained A/C unit has a variable frequency drive that allows the fan motor to adjust speed to meet current cooling load demands, with multiple compressors, and economizer coil that allows for free cooling based on outside air and humidity, medium efficiency filters, integrated control panel compatible with the building DDC control system. The supply air ductwork is constructed to medium pressure SMACNA standards as part of the base building.

Electrical / Lighting System:

The building power distribution system will be derived from Dominion Virginia Power transformers located on a concrete pad adjacent to the building. The power throughout the building will be distributed from one (1) 4000 (this should be 3000 per Dominion) amp 277/480V switchboards located in ground floor switchboard room. The power to base building loads will be distributed by conduit and wire risers. The power to tenant floors will be provided from one 3000 amp bus duct and associated bus duct plug in units. The emergency power to Plaza east is supplied through a diesel power unit, producing 150 kW, 187.5 kVA at 480Y/277 Volts. Lighting and telecommunications will be put in on behalf of the tenants and was not under contract of the GC.

Conveying System:

Each building contains one three car group of 350 fpm traction passenger elevators. Each group is provided with two 350 fpm @ 3500 lbs. (passenger) and one 350 fpm @ 4000 lbs. (passenger/freight). The elevators will have an elevator card key access to all floors combined with a perimeter access security to each building. Each floor has emergency exits with stairs located centrally in each half of the building.

Fire Protection System:

Plaza East will be provided with a complete installation for a new Class A system with Style D, Style 6, and Style Z circuit types for multi-plex addressable, fire alarm system with all alarm, audio, elevator recall, mechanical units control, remote station notification, and security system interface. The installation of the project’s fire alarm system shall conform to the applicable sections of the NFPA-72 Virginia State Uniform Building Code, requirements of BOCA,NEC, and the Fairfax county Fire Marshal.

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