U.S. Capitol Visitor Center

The US Capitol Visitor Center (CVC) is the largest addition ever made to the Capitol Building in Washington, D.C. The CVC building, 50 feet underground, will front the entire east front of the Capitol. The Capitol itself encompasses 775,000 SF, while the completed CVC will contain 580,000 SF on three levels.

When completed, the CVC will preserve and maximize public access to the Capitol while greatly enhancing the experience for the millions who walk its historic corridors and experience its monumental spaces every year. GEI was the design engineer for the temporary excavation support system. GEI worked with Nicholson Construction Company, a specialty geotechnical construction contractor, who was a subcontractor to Centex Construction, the general contractor.

The construction of the Visitor Center required excavation to a depth of 65 feet, which is 35 feet below the existing capitol foundations and within one foot of the plan area of the foundation elements. Slurry walls with tiebacks were used for the excavation support. GEI’s design was coordinated with a revised construction sequence to provide cost and schedule savings while complying with strict settlement and distortion criteria for the adjacent U.S. Capitol Building.

GEI’s design included strength and stability evaluation of the excavation support system to resist the imposed loads due to soil, water, and the surcharges of the Capitol Building. In addition, deformation analyses were performed using finite element models to confirm compliance with movement criteria. GEI’s analyses included evaluation of excavation system deformation performance and the impact of the predicted ground movements on the Capitol Building’s historic fabric and evaluation of the innovative tieback schemes to reduce construction complexity.