The design required that Silman maintain a high level of sensitivity to the historic integrity of the facade and other non-structural elements while incorporating heavy load transfers and aggressive excavation.
This 5-story 1910 Beaux-Arts building was originally a luxury apartment building before being used as office space in the mid-1900s. In 2013, a new owner purchased the building with the intent to infill its existing courtyard and add a second, lower-level basement. The renovation needed to balance these goals with interior and exterior easements designed to protect this National Historic Landmark.
Silman provided structural engineering services for a penthouse addition and full footprint below-grade addition.
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The design required that Silman maintain a high level of sensitivity to the historic integrity of the facade and other non-structural elements while incorporating heavy load transfers and aggressive excavation.
In addition to underpinning the new lower-level basement, Silman’s designs incorporated strict vibration criteria for sound and camera studios to be located on the upper basement suspended slab. A new partial footprint penthouse created rooftop assembly space and views of the historic neighborhood.
New framing was incorporated with the existing structure to create a 70-foot-long steel truss. Placed between the second and third floors, this truss allowed for the removal of columns between the first and second floors, creating an auditorium space. Silman strictly controlled deflection to protect historic finishes and minimize floor slope.
A notable feature of the design was the approach used to achieve seismic code compliance for the lateral system of the building. As part of a performance-based approach, Silman performed a nonlinear analysis to evaluate the contribution of the existing masonry to the lateral resistance and to limit damage to the historic fabric under seismic forces. The resulting design achieved an optimal balance reducing the lateral demand on new components while limiting damage to the historic construction under seismic forces.
