DBI outlines peer-review, performance-based criteria for tall buildings including Transbay Tower

The Department of Building Inspection’s structural engineering staff briefed commissioners on how the city reviews tall buildings and the state of practice for seismic and fire safety. Ray Louie, a structural engineer with DBI, described two approaches: prescriptive adherence to code or performance-based design to meet the code’s intent. He said the agency uses a three-step performance evaluation (service, design-basis and maximum-considered earthquake) and has adopted guidance (AB 83) for performance-based seismic review of tall buildings.

Louie said DBI institutes structural peer review panels for very tall projects and draws on national and international expertise. He referenced 45 Lansing (Rincon Hill) as a recent project that went through peer review. On fire safety and egress, Louie said proposals for additional measures — including firefighter elevators or third means of egress — have been considered nationally and implemented locally in some form by the fire marshal.

Commissioners asked whether design criteria differ from other cities; Louie said San Francisco follows national codes with local amendments and uses site-specific geotechnical reports to set acceleration and design inputs rather than relying on Richter magnitude measures. On collapse or repair thresholds after a major quake, Louie summarized the three performance objectives and said repair feasibility depends on damage and building performance in the design earthquake.

Commissioners also asked whether a Transbay Tower peer-review panel will be convened; DBI said a panel will be formed once the project comes forward.