Built in 1972, Webb Tower is a 14-story residential tower providing student housing in an apartment-like setting with private bathrooms. The existing building is a concrete post-tensioned moment frame structure located on the main downtown campus of the University of Southern California (USC).
A preliminary analysis performed by Saiful Bouquet Inc. on the existing building identified seismic concerns that could result in significant structural damage during a major ground shaking. SB designed a retrofit scheme that would mitigate the major seismic deficiencies in the building, and meet the intent of the current building code which is “retrofitted buildings should, in general, be able to resist a major level of earthquake ground motion without collapse, but possibly with some structural as well as non-structural damage.”
Our seismic upgrade consisted of adding new exterior Buckling Restrained Brace Frames (BRBF) to improve the overall lateral load resisting capability of the building, as well as its stiffness against deflection. The new BRBF’s provided the necessary stiffness, strength, and ductility required in the event of a strong seismic disturbance. The use of BRBF braces minimized obstruction to office views and is less expensive and less intrusive than a conventional concrete shear wall scheme.