How vulnerable is your soft-story (apartment) building to earthquake damage?
Soft-story apartment buildings are prevalent in Los Angeles and Orange County which are also considered earthquake-prone territories, specifically Los Angeles. Soft-story / apartment buildings are at risk of earthquake damage however; seismic retrofits will help mitigate the destruction for vulnerable structures.
The main feature Soft-story buildings are easily recognized by is also the main reason for structures to collapse or fail in an earthquake. This popular design feature is known as, tuck-under parking (parking that is below raised parts of the structure), very common for apartment buildings. Cities are constantly updating CA building codes in order to adhere to Life Safety standards. Therefore, if your soft-story building is not up to current mandates by the City, Soft-story seismic retrofits are common and often-times mandated by the cost of Earthquake insurance and the future buyer will most likely discount the purchase price if the structure is not retrofitted not matter what City it is in (even if the city has no mandate) to prevent devastation in an earthquake.
What happens to a building during an earthquake? Most earthquake-induced building damage is a result of ground shaking. When the ground shakes at a building site, the building’s foundation moves with the Earthquake causing the structure built above the ground to move even more than the ground based on the height and weight of the structure. Some building types are better able to resist these ground motions better than others. Soft-story apartment buildings in Los Angeles and the San Fernando Valley built prior to 1980 are at risk of collapsing during an earthquake. The first story is far too weak to support the entire structure above during an earthquake.
Older Soft-story building design does not comply with current Life Safety seismic building codes. There are local earthquake building codes that impact buildings in different cities. Many cities in California are taking the initiative to pass local legislation requiring the assessment and retrofitting of specific structure types that have been demonstrated to be at risk during seismic events.