Project Description /OverviewNabih Youssef Structural Engineers (NYA) provided structural analysis for the three separate structures built from the 1960's to the 1980's which make up the San Francisco Hilton Complex located in Downtown (Union Square) San Francisco, CA. Structural engineering services were provided for the seismic strengthening of Tower III, an early 1960's cast-in-place punched shear wall structure with a classic soft/weak story condition, which the owner wanted to mitigate with the least impact to the hotel and its daily operations.
Through the use of 3-Dimensional nonlinear analysis, NYA developed a simple and cost-efficient retrofit scheme, by locating a limited number of concrete shear walls in optimal locations around the perimeter of the building. The locations of the new walls were carefully coordinated with the owner and the design team to limit the impact to the hotel function and operations, and allow the hotel to stay open during construction.
The placement of the new walls was done in such a way that they can be anchored to the existing basement walls, therefore eliminating the need for new foundation work - a substantial cost savings.