LERA Wins ACEC NY 2020 EEA Platinum Award for 2050 M Street Office Building
LERA is proud to announce that 2050 M Street has won the Platinum Award for Structural Systems at the 2020 ACEC NY Engineering Excellence Awards Program. The winners will be recognized at a black tie gala on Saturday, April 4, 2020 in the ballroom of the Hilton Midtown in New York City. LERA led the structural design of the new office building, owned by Tishman Speyer and located in Washington, D.C.'s "Golden Triangle" business district. The architect is REX Architecture.
Home to CBS’s Washington Bureau, the 450,000-sf (42,000-sm) 2050 M Street combines the traditional typology of D.C. office buildings with an all-glass curtain wall made of curved floor-to-ceiling panels that maximize transparency and yield panoramic, column-free views.
The 900 identical insulated-glass panels that compose the façade are curved through a heat roller tempering process and are structurally efficient, meeting wind load requirements and enabling a thinner monolithic outer lite than normal, thus enhancing transparency. Each perimeter column is pulled in 12 ft from the façade, with the ceiling of each floor tapered to the depth of the structural slab at the exterior, further emphasizing the permeability of the building.
The building was originally designed to have a conventional column grid layout and regular concrete slabs, with columns placed at the perimeter. By offsetting the perimeter columns inward 12’-6” from the façade, resulting in a 40- by 30-ft column grid, and by using 8” post-tensioned concrete floor slabs with 16” drop panels, the structural floor depth was minimized and the ceiling heights and open façade were maximized
The deflections of the cantilevered slab edges were a major design and construction consideration, and understanding future creep movement during the installation of the unique curtain wall was critical. The post-tensioning minimizes the slab’s self-weight and cantilever deflections, and counteracts future deflection-related creep movement. LERA performed extensive analyses, using multiple models, to best predict and correlate long-term deflections with the contractors’ surveys and assist the team in coordinating the façade installation. In addition, the penthouse roof, which supports extra loading from the green roof, is cantilevered 30 ft in one direction and 25 ft in the other direction, enabling a completely column-free perimeter space that in effect creates a “structure-free” experience.
Construction was intricately phased to accommodate the demolition of two adjacent buildings and the construction of an entirely new building in their place while ensuring that CBS News could maintain operations as normal, all while achieving the project schedule and budget. The first phase entailed construction a portion of the new office building specifically for CBS over the demolished adjacent parking lot and garage at 2020 M Street. This allowed CBS to maintain operations in their existing facility during the first phase of construction, and then to seamlessly transition to the new facility before the start of the second phase of construction.