U.S. Department of the Interior in Washington, D.C.
Thornton Tomasetti is providing structural design in support of the phased renovation of a 1936 marble and limestone building. Occupying two city blocks, the 120,700-square-meter structure consists of a concrete-encased steel frame with a flooring core of hollow terra cotta tiles resting on pile foundations.
The project involves improvements to building infrastructure to comply with current health and safety standards, upgrades to HVAC and MEP systems, and addition of code-compliant exit stairs and ramps. To allow continuous use of the building, work was divided into six phases and included the addition of internal swing space to house DOI staff during construction. GSA used the modernization as a pilot project for the LEED Existing Buildings Program certification.
Thornton Tomasetti performed initial inspections and evaluation of existing floor systems for live load capacity. Due to limited existing documentation, an extensive non-destructive and limited destructive testing program was undertaken to obtain sufficient structural information. Design has been completed for all six phases, and construction is ongoing.
In 2002 the project was expanded to include a feasibility study for blast-mitigation windows and the design of associated supplemental framing. Also added was a design-build program for the installation of retractable bollards at all parking ramps.
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