The challenge was to meet acceptable seismic safety for the hospital. The building had irregular special moment-resistant trusses that do not meet Office of Statewide Health Planning and Development (OSHPD) - Senate Bill 1953 Life Safety Requirements with a Standard Performance Category (SPC) one rating.
The results of the preliminary analysis indicate that it is very likely the existing buildings can be upgraded to an SPC five rating. The most promising strategy to achieve this goal, while providing flexibility for future programs and functions, ties the North and South Patient Towers to the Professional Tower above the Plaza Level to create a single, U-shaped building. A 25-foot-wide strip of diaphragm extending along the full length of the western edge of the Professional Tower is used to tie the buildings together. The floor plate of the North and South Patient Towers will be expanded by approximately 16 feet along both the north and south sides of the building, not only increasing the performance level of the building, but also adding valuable programming floor space.