On 17 January 1994, an earthquake of magnitude 6.4 struck Los Angeles. This quake came to be known as the Northridge Earthquake and it brought attention to structural issues of many buildings that are located in the earthquake prone areas. This led to the start of many retrofitting companies in Los Angeles.
In the Northridge Earthquake, the ground floor of Northridge Meadows apartment complex collapsed leading to the immediate death of 16 residents on the ground floor. This building collapsed because it was a soft story building. Soft story buildings are those, in which the ground floor is less rigid than the floors above it. These buildings are very much susceptible to damages due to earthquakes.
Soft Story buildings have large number of non-reinforced openings. These openings usually accommodate parking spaces, expansive lobbies, large windows, etc. If the building is erected without proper design and planning, they can be susceptible to the lateral forces and can collapse during earthquakes.
Soft story buildings are a big issue in cities like San Francisco and Los Angeles, which have a very high population density. Los Angeles has many soft story buildings that need immediate improvement, and that is why the city is implementing Ordinance No. 183893. This is a mandatory earthquake retrofit ordinance aimed at reducing the hazards caused by an earthquake to a building.
As per a recent study conducted by the California Institute of Technology, there are around 20,000 soft story buildings in LA, out of which, only 800 have been improved and upgraded. San Francisco also faces same issue and experts predict that a major earthquake may hit the Bay Area in the upcoming years. If this happens, 80 percent of the soft story buildings in the city would collapse or may get damaged beyond repair.