Seismic Retrofit of the Queensboro Bridge, NYC: assessment of existing foundations

The Queensboro Bridge connecting the boroughs of Manhattan and Queens is a critical transportation link in New York City. The structure, which opened to traffic in 1909, is a two-level, five span truss bridge (of 1135 m length) with extensive approaches and approach ramps. This major east coast bridge underwent an in-depth seismic condition assessment that combined the efforts of seismologists, geotechnical and structural engineers.

We were hired by the geotechnical consultants (MRCE, NYC) to calculate the foundation impedance matrices for the bridge piers of Queensboro Bridge. The calculations involved 3D FE analyses accounting for complicated phenomena such as interaction of adjacent tower legs etc. The analyses resulted in a set of elastic and non-linear impedances (representing the soil-foundation stiffness) to be utilized in the seismic analysis of the bridge.