A soft-story retrofit is the strengthening of a building against seismic forces by stiffening its weakest elements. soft-story buildings are typically composed of a ground floor with large openings (garages, tuck-under parking, or retail spaces) and one or more floors above that have fewer openings. The rows of columns on the upper floors bear the brunt of the weight during an earthquake, while the large openings on the lower floors act as doors, swinging open and subjecting the building to additional shaking and potentially causing collapse.
Types of Soft-Story Retrofits
There are several ways to strengthen a soft-story building against seismic forces. One is to add shear walls, which are walls that are reinforced with steel or concrete to resists the force of an earthquake. Another is to add bracing, which adds lateral support to the structure. Cross bracing, for example, ties opposing walls together so that they work together to resist seismic force.
Another type of soft-story retrofit is base isolation, which involves separating the building from the ground with a layer of flexible material such as rubber pads or steel springs. This flexible layer absorbing some of the energy from an earthquake, protecting the building from damage.
Finally, another option for retrofitting a soft-story building is to add diagonal steel struts or “chess pieces.” These struts connect the upper floors to the foundation and help prevent progressive collapse—the situation in which one failure leads to a domino effect of failures throughout the structure.
Conclusion: Why Retrofit?
So why bother with all this extra reinforcement? The answer is simple: safety. Earthquakes are unpredictable and often destructive events, and soft-story buildings are particularly vulnerable to their effects. By retrofitting these buildings, we can help protect both occupants and property in the event of an earthquake.
A soft-story retrofit is the strengthening of a building against seismic forces by stiffening its weakest elements. soft-story buildings are typically composed of a ground floor with large openings (garages, tuck-under parking, or retail spaces) and one or more floors above that have fewer openings. The rows of columns on the upper floors bear the brunt of the weight during an earthquake, while the large openings on the lower floors act as doors, swinging open and subjecting the building to additional shaking and potentially causing collapse.
Types of Soft-Story Retrofits
There are several ways to strengthen a soft-story building against seismic forces. One is to add shear walls, which are walls that are reinforced with steel or concrete to resists the force of an earthquake. Another is to add bracing, which adds lateral support to the structure. Cross bracing, for example, ties opposing walls together so that they work together to resist seismic force.
Another type of soft-story retrofit is base isolation, which involves separating the building from the ground with a layer of flexible material such as rubber pads or steel springs. This flexible layer absorbing some of the energy from an earthquake, protecting the building from damage.
