When you live in an earthquake-prone area, some very strict building codes exist. These building codes are designed to make sure that any building is going to be strong enough to survive an earthquake. Part of those codes will be about the lateral load resistance that a building has. The more lateral load resistance, the stronger the building is, and the more it is likely to survive an earthquake. A lateral load is one that acts against the building in parallel to the ground. Buildings that have soft stories have issues with their lateral load resistance, making them less safe in earthquakes.
Soft Story Buildings
A soft story building has at least one story that is not as strong as the rest of the stories in a building. Generally, those stories don't have as much structural support as other stories in the building, because they are built with wide open spaces. For example, a building that has a lot of retail space on the ground floor could be a soft story building because the spaces just don't have as much support as a residential level would. It's the same with buildings that have garages under the living space. Many cities in earthquake-prone areas are requiring older, soft-story buildings to be retrofitted so that they will fit within current building codes.
Retrofitting a soft story building isn't always a quick process. The actual retrofit work may be able to be done in a couple of weeks, but there is more to the process than just adding in reinforcements. The first part of the process is for an engineer to examine the structure. The engineer is going to be able to figure out the current lateral load of the building and where it stands in comparison to the current building codes. Then the engineer and the construction company will get together and make a plan about what it will take to get the building up to the current code. That can include doing things like installing steel frames along support systems and pouring more reinforced cement supports. Once the plan is in place, the retrofit contractor will be able to get the work done, making it stronger and compliant with current codes.
Building codes exist to make sure that all new structures are as safe as possible. Those codes can be retroactive as well, requiring older buildings to come into compliance. In earthquake-prone areas, strict building codes regulate soft-story structures and may require those buildings to get a soft story retrofit.Share