Process of reinforcing a building’s quake-vulnerable floor/floors to make the entire structure more resistant to the shear forces present during an earthquake.

The City of Los Angeles has recently passed an Ordinance (Los Angeles City Ordinance for Soft Story) requiring the retrofit of “Soft-First-Story” wooden buildings and non-ductile concrete buildings to ensure life safety.

A typical soft-story building is a building consisting of two or more stories located over a ground level with large openings, such as tuck under parking, garages, or a commercial store front. Without proper strengthening of these buildings, the building may be subjected to structural failure during and/or after an earthquake. If the sideways movement during an earthquake is particularly strong, the weak supports in the soft stories could give way. This, in turn, would cause the upper floors to fall onto the lower floors, thereby crushing whatever or whoever is on those lower levels. This type of structural failure is known as “pancake collapse.”

Under the ordinance, seismic retrofits of the wooden structures must occur within 7 years. Within this time period, there are milestones that owners must meet to show that they are taking steps to have their buildings assessed and, if deemed necessary, strengthened.

If your building has soft stories, get it retrofitted as soon as possible. The following are some of the reasons why prompt action is advised:

  • Minimize liability loss
  • Lower earthquake insurance premiums
  • Save on interest
  • Save money

Plywood Shear Walls

Concrete Shear Walls

Braced or Moment-Resisting Steel Frames

Cantilevered Steel Columns

Foundations and Grade Beams

Foundation, Roof and Wall Anchors

Continuity Ties

Collector Detailing

Strenghtening Unreinforced Walls

Base Isolation

Jacketing of Columns