300 New Jersey Avenue, NW
300 New Jersey Avenue, NW, is one of Washington, D.C.’s most notable projects, not only because of its close proximity to the U.S. Capitol and Senate office buildings, but also for its unique and complex design.
300 New Jersey Avenue, NW, is the first building in Washington, D.C. designed by the renowned British architect Lord Richard Rogers. The project team was dedicated to implementing his vision.
The 10-story, 255,000 square-foot building is linked to two wings of the neighboring, L-shaped Acacia Building by a dramatic ten-story glass atrium. A bright yellow structural steel “tree” houses much of the atrium’s mechanical systems, and a glass observation elevator runs along the tree in the center of the atrium. Several elevated platforms and walkways cross the atrium at different heights, linking 300 New Jersey Avenue and the Acacia Building’s interior spaces.
The building’s floorplan cantilevers eight feet over New Jersey Avenue, allowing for unparalleled views of downtown Washington, D.C. and the nearby U.S. Capitol. It also features floor-to-ceiling windows, six levels of below-grade parking, and numerous sustainable elements.
The excavation, support-of-excavation, and foundation work required for 300 New Jersey Avenue, NW was extremely complicated. The project’s small, urban footprint included underground proximity to a Washington Metro tunnel and the Tiber Creek storm drain and sewer line. Meanwhile, excavation for the parking garage was one of the deepest in Washington, D.C. history, reaching 60 feet below grade and 39 feet below the existing ground water level. To protect the excavation, Clark Foundations devised an intricate shoring system mimicking a bathtub to successfully perform the necessary excavation and foundation work. Because of the nearby structures and delicate surroundings, an elaborate monitoring plan was developed for the shoring system.
300 New Jersey Avenue contains very complicated steel elements, which are key to the innovative, and beautiful, open atrium. Although the trusses comprising the structural steel framing system seem identical, this is an illusion. The subcontractor used Building Information Modeling (BIM) software to transform two-dimensional truss drawings into an accurate, three-dimensional reality. Trusses had to be assembled according to strict tolerances.
A boomerang truss and supporting lattice columns help brace the lobby’s tree structure. The boomerang truss is offset from the supporting tree and the tie-back rods which help support it. This truss has a tapered triangular section with circular chord and web members. Tension rods support the truss and the stair platforms and, because of the forces applied to the rods, they had to be pre-tensioned. Two lattice columns support the boomerang truss at each end. These are constructed of pre-tensioned cables with roller pins at each outrigger to allow for zero loss in pre-tensioning friction. Structural redundancy in the columns has been provided by using double cables at each of the three lines of cables around the main pipe section.
300 New Jersey, NW earned LEED Gold certification. The building features a high-efficiency drip irrigation system, and high-efficiency plumbing fixtures will save nearly 33 percent of water used, or over 361,725 gallons annually. A combined reflective and green roof system reduces the urban heat island effect while improving stormwater quality.