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Federal DOT Headquarters

Washington, DC

An economical solution to the program and physical requirements of the government complex was achieved with a cast-in-place reinforced concrete frame combined with blast-resistant precast facade. The complex, with its bold colors of dark green and red, provides an outwardly open appearance and perception to the public.

Design Challenge

Blast Design

There were several security measures that were required to be incorporated into the design after 9/11 and therefore the precast was engineered for blast resistance. The most intrusive change to the design was the result of the required increase to the building setback from the street.  The building was originally designed to be 20-feet from the defensible perimeter inside the street curb line to the face of the building; this dimension was increased to 50-feet. 

The design of all of the exterior façade elements provide for the higher peak pressures and impulses regardless of the standoff distance from the explosive device or the calculated height above the explosive device. Additionally, in those areas where the standoff distance is less than 50-feet, the design provides for an “equivalent level of protection” to those exterior façade elements which would be affected.

More finesse is required in designing precast panels to handle various blast loads. It is imperative to make the panels both efficient and safe. Typically, blast-resistant panels are thicker than conventional precast, contain additional reinforcement and connection hardware is increased.

 

Precast System Details

296,430 square feet and 1,887 pieces

 

Precast Advantages

 Attractive Appearance
The pattern, texture and color variations of the architectural precast wall panel components enabled simple, clean shapes which enhance an image of strength with aesthetic beauty. Three mix designs were used: white, red, and dark green. The bold dark green and red colors were achieved primarily with pigments. All finishes are a light acid wash. Granite panels were cast into many of the white precast panels, particularly at the building base and at the New Jersey Avenue façade.

Low Noise Transmission
The density of concrete panels provides excellent sound attenuation, reducing transmission of airborne sound from the exterior street to the interior office space.

Energy Conservation
The precast concrete components reduce energy consumption in several ways: 1) Precast construction allowed for minimal air infiltration; thermal mass delays internal temperature changes and reduces peak heating and cooling loads; 2) The sculptured shapes facilitate the design of shading devices for window areas.

Durability
The precast concrete provides a façade that is exceptionally resistant to impact, corrosion, weathering, abrasion and other ravages of time, making it virtually maintenance free.

Dual-Use
Ability to combine the structural facade protection and exterior cladding into a single element.

Economy
The large size of precast panels reduces the quantities of applied sealant, typical of stone cladding and the many vulnerable mortar joints of traditional masonry veneer construction.

Quick Erection
Panel fabrication can be initiated at a remote site while structural framing is still being constructed.  The overlap saves time and minimizes on-site staging areas.  Since the panels require only panel-to panel or panel-to-window sealant and exterior glazing to be considered weatherproof, interior trades could begin work much sooner than with conventional construction.

In order to increase erection efficiency and reduce cost, spandrels panels and column covers are combined wherever possible. The result is a full spandrel section at the top, with column covers extending downward, creating an "E" shape which is rotated 90 degrees clockwise.

General Information

Jacksonville, FL
Architect:
Michael Graves and Associates in association with DMJM Design / AECOM
Contractor:
Clark Construction
Owner:
JBG/Federal Center, LLC

Precast Systems

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Project Aesthetics

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