Wood-framed, soft-story apartment buildings were an iconic part of Southern California’s rapid growth and car-crazed culture prior to 1980. With an open ground floor for parking, and dwelling units stacked above, they maximized land use at the expense of safety.
These structures have since been shown to be among a community’s most deadly. Perched as if on stilts with their open front walls – they are prone to collapse in a major earthquake.
How vulnerable is the Southern Cities region to this threat? In Long Beach alone, there may be thousands of these structures, according to a new mapping tool developed by the U.S. Resiliency Council in partnership with Esri. Together, they have created an interactive map that identifies the number of potentially vulnerable soft-story buildings in cities throughout Southern California.
Statewide, there are estimated to be more than 60,000 locations in California with these older multi-story apartment buildings in cities without mandatory retrofit ordinances, representing nearly 800,000 units, according to the USRC. If 30% of those structures need retrofitting, that is almost 250,000 units. At 2.5 people per unit, that represents 625,000 people at risk of death, injury or homelessness when a major earthquake strikes near their homes. (Visit http://bit.ly/3GQAN7m for more information.)
Those at-risk structures also represent thousands of apartment owners whose lifelong investments may be in jeopardy. How would you manage, if your building was seriously damaged, your rental income lost, and you faced significant cleanup and repair costs, as well as owner’s liability for earthquake damages?
The city of Long Beach does not mandate seismic retrofits for wood-frame, soft-story buildings – but it is working to develop a Building Resiliency Program to reduce the risk of earthquake-related damage and promote life safety in the city’s commercial and multifamily buildings.
When built prior to 1978, these structures can be extremely vulnerable to collapse in a major earthquake. Because of their design, they lack the ability to withstand lateral forces that push the building from side to side. The swaying can cause the first floor to collapse, and the upper stories to pancake on top of it. Retrofit construction for soft-story buildings usually entails the installation of a steel moment frame or frames, a sturdy foundation and drag lines to absorb seismic ground motion and prevent swaying.
We saw these structures collapse in the 6.7-magnitude Northridge earthquake of 1994. The images of the flattened multi-level soft-story Northridge Meadows apartments – and the smashed vehicles beneath them – still rattle people today.
Earthquake disasters come without warning, and their devastation can happen instantaneously. The situation requires foresight to resolve. We can’t make earthquakes go away, but we can retrofit structures to withstand them.
If you own a building that you believe may be vulnerable to damage, it’s important to educate yourself on cost-effective measures that can be taken to save lives, protect your assets, and preserve the well-being of the community-at-large. Find out the risks you face. Call Optimum Seismic at 833 978-7664 for a free building evaluation today.