Structural design features on this four-story addition allowed the building to overcome various existing conditions, including unstable soils, an existing building with no reserve support capacity, and a small, urban site. Investigations determined that underlying soils were comprised of uncontrolled fill and compressible clays, which limited the allowable soil bearing capacity for foundations. Soil bearing capacity was even more limited for new footings located adjacent to the existing structure. Faced with these limitations, RBA designed floors in which lightweight concrete acts in composite action with steel framework. A cantilevered, steel framing system was selected, allowing new foundation loads to be located further from the existing building. Exterior wall construction is a lightweight assembly of metal studs, brick, and precast concrete panels. Additional programmatic requirements included designing a below ground Physics Department, which is virtually vibration-free.
