Soft Story Retrofit, Berkeley CA
This was a voluntary seismic retrofit of a soft story building located in Berkeley, California. The owners of the 4-unit condominium building were concerned about potential collapse or excessive damage in the event of a significant earthquake.
The solution involved a combination of strategies. At the rear of the building where connectors were installed to connect the floor through the rim joist to the existing foundation. For the open front created by the garages, a system of steel columns connected by a concrete grade beam was utilized. Traditional plywood shear walls were used on the long sides of the building.
To minimize the amount of foundation work, shear walls were sized to minimize the size of holdowns. Where larger holdowns were required, we instead doubled up smaller holdowns that could still be installed into the existing foundation.
