A Shinto shrine in the Japanese coastal town of Minamisanriku has been the center of its community for centuries. In 1960, a tsunami generated by the great Chilean M9.5 earthquake swept into the ocean bay and damaged the shrine. The priest’s house situated at a higher elevation than the shrine had been spared any damage. The community came together and not only repaired the shrine but moved it up the hill, 50 feet above its previous location, to protect it from future events.
Imagine that it’s 4:30 a.m. and suddenly you’re awakened by strong shaking in your home. Half asleep, you hang on to your bed hoping that the shaking will stop soon. All of a sudden, the floor gives away and you fall. You think, “What just happened? How could this have possibly occurred? Am I alive?”
These could have been the thoughts of Southern California residents living in one of the many apartment buildings, which collapsed on January 17, 1994, during a 6.7 magnitude earthquake. The Northridge Earthquake brought awareness to buildings in our communities with a structural weakness known as a soft story, a condition that exists where a lower level of a multi-story structure has 20% or less strength than the floor above it. This condition is prevalent in buildings with tuck-under parking and is found in multistory structures throughout San Francisco, Los Angeles and other cities (see Figure 1). These structures are highly susceptible to major damage or collapse during a large seismic event (see Figure 2).
Soft story retrofits help to strengthen our communities and make them more resilient to major disasters. There are several resources available to structural engineers that need to retrofit weak-story buildings. Some of these resources are mentioned in our September 18 blog post.
During the 2014 SEAOC Convention held in Indian Wells on September 10-13, speakers discussed different methods, analysis and research that address the behavior of various materials and construction types during seismic events along with approaches to retrofit historically poor performing structures. This information can be viewed from the convention’s proceedings available at www.seaoc.org.
On October 20, 2014, the Structural Engineers Association of Southern California (SEAOSC) will be hosting their 4th annual Strengthening Our Cities BAR Summit in downtown Los Angeles. This event brings together many different stakeholders in our built environment, including public officials, building owners and managers, business owners, insurance industry representatives, emergency managers and first responders, and design professionals.
Many prestigious thought leaders, including USGS Seismologist Dr. Lucy Jones will be speaking at the summit, discussing such topics as tools and analysis methods for retrofitting vulnerable buildings and the Building Occupancy Resumption Program (BORP).
Expect a great day full of useful information about ways to strengthen our communities and prepare for major earthquakes as well as opportunities to network with like-minded peers. For additional information and to register, visit www.barsummit.org. We also hope you’ll visit our booth. We look forward to speaking with you there.