Seismic-proof steel bracing? San Francisco’s Town Hall Restaurant
Julia Ulida

#Buildingoftheweek is a new series of content that the Tensorflight team will be publishing as a way of sharing interesting architecture, but also how unique elements of many buildings impact it from an insurance perspective. 

To start the series, we’re looking at Town Hall, a popular eatery in San Fransisco. What makes the building unique is the seismic steel bracing inside of it. 

San Fransisco, and the entire bay area, are built on the San Andreas fault, making the area more prone to earthquakes and tremors. The impact that these natural disasters have on buildings needs to explanation. 

Technical specifications

Located at 342 Howard St, San Francisco, this 3-storey building has a height of 78.8ft with the Tensorflight tool estimating a floor area of 9876 square ft. Constructed of brick in 1907, the building has been meticulously maintained over the last 100 years. 

The building was one of the first structures rebuilt after the 1906 San Fransisco earthquake and originally housed the Marine Electric Company. Today, the building is one of the few in the district from that era.

Steel bracing 

As it was built in the wake of the seismic destruction of the city, architects drew on the latest technology and research and rebuilt the building with extra rigidity. Diagonal steel beams have been placed between vertical and horizontal trusses to increase rigidity and minimise the movement of the building during an earthquake. 

Externally, the brickwork classing covers these diagonal trusses entirely, making them only visible from the inside. Internally, the trusses have been painted to match the interior decor of the room in which it’s featured. 

In a seismic event, it’s not the shaking of the ground that generally causes the most damage, but rather the building’s back-and-fourth movement of itself that causes damage. Town Hall’s x-shaped bracing adds significant rigidity to the building, and while not entirely removing horizontal oscillations, it has been proven to minimise them, and thus minimise the damage the building can cause to itself in a seismic event. 


The steel bracing in the Town Hall Restaurant helps insurance companies better understand earthquake risk and change insurance premium. The replacement costs of the building, according to Tensorflight, stand at USD$3,918,000. 

The bracing also adds a unique design concept to the interior space and is one of the reasons that it’s almost the only early-20th-century building that still stands in the Bay area.  

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