A first-of-its-kind study released Thursday by San Francisco city officials provides 16 recommendations the city can use to ensure that its tall buildings are seismically safe.
The study examined the city’s current 155 tall buildings-defined as being 240 feet high or higher-and looked at how modern engineering practices and lessons learned from the 1989 Loma Prieta and the 1994 Northridge earthquakes could be applied, ahead of the next major disaster.
In addition to providing the recommendations, the study also looked at the seismic risks associated with tall buildings, standards for evaluating tall buildings after an earthquake, reoccupying buildings after earthquakes, and the benefits of implementing new construction and engineering practices.
“Having this information available is a huge step forward in our ability to think collectively and proactively as a city about the seismic safety and the resilience of our tall buildings and the implication in their surrounding neighborhoods,” City Administrator Naomi Kelly said.
According to one of the authors of the study, Stanford University engineering professor Greg Deierlein, many of the 16 recommendations provided are related to improving construction issues as well as foundation issues.
“Current building codes are really geared to protect the life-safety of a building and don’t necessarily address recovery,” he said, adding that the demand for office space and residential units in downtown San Francisco highlights the need for the study.
“San Francisco has one of the most stringent building codes in the country. We always are looking at how we can improve those codes,” Kelly said. “What’s different now is that we’re looking at existing buildings. We’re always moving forward in reviewing our codes for new buildings, but now we’re going to go back and look at existing buildings and see what can we do to make them more resilient.”
The U.S. Geological Survey estimates that San Francisco has a 72 percent chance of experiencing a 6.7-magnitude or stronger quake before 2043.
The Tall Buildings Safety Strategy comes out a little more than a week after cracks in two steel beams forced the closure of the recently opened Salesforce Transit Center, and more than two years after the 58-story Millennium Tower was discovered to have sunk 16 inches.
The study, which took 14 months to complete, was put together by the City Administrator’s Office, in collaboration with the Office of Resilience and Capital Planning and the Department of Emergency Management. The study can be found at https://bit.ly/2Ph0FvC.