The eight 40-foot-tall super columns supporting the new addition are threaded through the existing structure to new independent foundations. The project team also modified existing framing to insert a new elevator and stair core.
St. Luke's School is located within the Greenwich Village Historic District.
- St. Luke's School is located within the Greenwich Village Historic District.
This K-8 school wanted to nearly double the space of its 1950s building to accommodate a growing student population. As is common in Manhattan, the only strategy for significantly expanding the two-story, 27,000 steel structure was to build up.
To avoid a costly seismic retrofit of the existing structure and to reduce the impact of the construction on the existing building below, Silman designed the addition as a completely independent structure supported on super columns.
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The eight 40-foot-tall super columns supporting the new addition are threaded through the existing structure to new independent foundations. The project team also modified existing framing to insert a new elevator and stair core.
Double-height steel trusses at the addition’s longest cantilevers and spans help the building meet load and deflection criteria. They are exposed to the interior in several locations, adding visual interest. These trusses are supported on custom built-up steel girders cantilevering over the super columns below. Silman designed custom shapes to keep the girders shallow enough to fit between the new structure and the existing roof.
Photo credit: ABA Studio.
Gymnasium trusses.
Classroom trusses.
Silman coordinated the foundation design with the Port Authority of New York and New Jersey (PANYNJ), the agency that owns and operates the PATH train tunnel that runs beneath the northwest corner of the site. Four of the eight super columns are set back up to 30 feet from the face of the building and supported on 170-ton steel caissons; the other four super columns are supported on shallow spread footings. To isolate the new structure from vibrations due to passing trains, Silman detailed the column bases to include two-inch-thick isolation pads, with isolation material between all steel and concrete foundation elements.
St. Luke School’s new addition was constructed without any lost school days or student displacement. The school now contains a larger gymnasium, new classrooms and support spaces, and a future outdoor roof play space.
