By Matthew Chin and Wileen Wong Kromhout
The unexpectedly poor performance of modern buildings during recent major earthquakes has demonstrated that revisions to design practices are needed to ensure that future construction is more resilient.
“The structural damage observed after powerful earthquakes over the past few years — particularly in Japan, New Zealand and Chile — has been eye-opening and concerning,” said John Wallace, a professor of civil and environmental engineering at the UCLA Henry Samueli School of Engineering and Applied Science and principal investigator of UCLA’s Network for Earthquake Engineering Simulation (NEES@UCLA) laboratory.
Now, a research team led by Wallace and co-principal investigators Jack Moehle and Claudia Ostertag of UC Berkeley has received a $1 million research grant from the National Science Foundation’s National Earthquake Hazards Reduction Program to examine these construction issues, focusing in particular on the design and performance of modern buildings’ structural walls.
Structural walls — solid, reinforced concrete walls that extend from a building’s foundation to its roof — are one of the most common systems used to resist earthquake forces in the U.S. and around the world. In many buildings, these walls surround stairs and elevators or are located at the building perimeter.
Recent advances in wall design and construction practices have resulted in thinner, more efficient wall geometries that are pushing the performance limits of this structural system, but the recent damage seen in Japan, New Zealand and Chile shows the need for a critical reassessment.
“These earthquake-prone countries have modern building codes that are very similar to the codes used in California,” said Wallace, who in 2010 led a field team in Chile that assessed building performance and monitored how buildings responded to strong aftershocks using NEES@UCLA equipment. “Our research team will investigate reasons for damage, and lack of damage, as well as ways to improve building codes so buildings are more resilient to the intense shaking from powerful earthquakes.”
The research team will explore design and performance limits for structural walls, considering both conventional wall construction practices and innovative construction practices. Testing will include stressing full-scale structural components to failure in NEES laboratories in the United States. The researchers will also collaborate with colleagues at Japan’s National Research Institute for Earth Science and Disaster Prevention on shake-table tests of buildings with structural walls. The team will then look to demonstrate innovative yet practical new systems that can transform design practices, and to develop performance-based design approaches for both conventional and innovative buildings.
Wallace will also chair a special session on these issues at the 15th World Conference on Earthquake Engineering, to be held in Lisbon this September.
“It’s an exciting project with the long-term goal of introducing code changes that address these previously unforeseen problems,” Wallace said. “And certainly, the outcome of this research will benefit California, as well as other parts of the country and world that are in seismically active regions.”
Data from the project will be archived and made available to the public through the NEES project warehouse and data repository.
NEES@UCLA is a large-scale earthquake experimental resource site that specializes in the field testing and monitoring of geotechnical and structural performance.