This category of buildings, sometimes referred to as non-ductile concrete buildings, have shown poor seismic performance in recent earthquakes in many parts of the world, engineering experts with the National Science Foundation reported Monday.
"We have learned the lesson over and over again in past earthquakes in the United States and abroad that many of our nation's older concrete buildings, where many of us live and work, are not safe during an earthquake," engineering Professor Jack Moehle at the University of California, Berkeley, said. "This project used the NSF-funded NEES [Network for Earthquake Engineering Simulation] laboratories around the nation to provide building owners, occupants and public officials with solutions to make these buildings safer."
In a research effort to identify the number and types of older concrete buildings in a typical city, Los Angeles was chosen, the researchers said.
As a result of the research, experts provided Los Angeles officials the addresses of about 1,500 older concrete buildings within the city, including residential, commercial and critical service facilities such as hospitals, and estimated about 5 percent of these buildings may have a high risk of collapse.
"Many non-ductile buildings remain standing long enough after an earthquake occurs for occupants to escape because their columns retain enough strength to support the structure," Moehle said. "Our goal was to identify those non-ductile buildings that will not remain standing, what we would call 'killer buildings.'"
The NEES, a shared network of 14 experimental facilities, collaborative tools and a centralized data repository all linked on the Internet, is based at Purdue University.