Silman provided comprehensive structural engineering services for the renovation and expansion of Smith’s main library building, including design and detailing of two feature stairs. As is the case with many long-established campus buildings, the 1909 Neilson Library had seen multiple eras of piecemeal alterations. Silman’s first task was the careful excision of additions from 1962 and 1982 as well as renovations to the main building interior. This preliminary work paved the way for restoring the original design and making the central library feel more open.
Because the project’s large-scale modifications triggered a seismic lateral system retrofit, Silman designed a new system of steel braced frames located just inside the existing masonry bearing walls. These new frames are supported on a new foundation system of pile caps and grade beams.
The new construction consists of two “jewel boxes” wings located to the north and south of the original H-shaped library. The south wing holds special collections, archives, and rare books; the north wing includes learning spaces, a café, and a digital media hub. The jewel boxes are made up of steel-framed composite slab construction with reinforced concrete walls. Silman designed the steel framing to accommodate over 800 MEP penetrations.
A site with clay soils and a high water table required creative foundation solutions. Instead of dewatering or excavating the existing clay layer, which would have significantly impacted the overall project schedule and costs, the project team installed new pile foundations at the south basement by locally drilling through the existing mat slab and using the new pile caps to help resist hydrostatic uplift. The basement roof slab and part of the top of the foundation wall were replaced with new landscaping and a basement roof structure buried below grade.
Despite the increase in interior floor area, the project team managed to decrease the building’s footprint by about 25%, returning lost green space to the adjacent grounds in deference to Frederick Law Olmsted’s original 1893 design. The Neilson Library renovation project, designed to achieve LEED Gold certification, is part of a larger campus library master plan.