The building at 410 Broadway is a New York City Landmark built in 1915 and constructed with wood floor joists that frame to masonry bearing walls more than 2 ft thick. The new tenant, Tribeca Oncology, planned to establish a radiation-oncology clinic on the first floor with a linear accelerator (LINAC) machine room in the cellar. The LINAC is shielded through the placement of 3 ft thick, high-density modular concrete block walls, a roof with interior lead lining, and a 4 ft thick mat foundation isolated from the structure by a seismic gap.
As structural engineer to Paik Architecture, SGH designed the mat foundation supported on sixteen micropiles, which were designed by the geotechnical engineer to reduce differential settlement and vibration within the tolerance of the LINAC. Because the building is adjacent to the subway, SGH monitored vibrations with a seismograph to check and confirm that vibrations were within tolerance.
Because the city building department mandated that the construction be non-combustible, the building required replacement of the first floor. SGH designed new floor framing, worked with the architect and Paik Construction to provide several variations in floor elevation, helped resolve field conditions and constructability issues, and addressed construction sequencing to allow removal of framing without jeopardizing the lateral bracing of the existing masonry bearing walls.