Slow motion testing probes how full-scale buildings collapse in earthquakes

Washington, August 26 (ANI): Scientists have recently tried an innovative "slow motion earthquake" testing that may provide a safer, far less expensive way to learn about how and why full-scale buildings collapse during quakes.

The method was developed by researchers at the University at Buffalo (UB) and Japan's Kyoto University.

"One of the key issues in earthquake engineering is how much damage structures can sustain before collapsing so people can safely evacuate," explained principal investigator Gilberto Mosqueda, UB assistant professor of civil, structural and environmental engineering.

"We don't really know the answer because testing buildings to collapse is so difficult. With this hybrid approach, it appears that we have a safe, economic way to test realistic buildings at large scales to collapse," he said.

The UB/Kyoto team's positive results could enable engineers to significantly improve their understanding of the mechanisms leading to collapse without the limitations of cost, reduced scale and simplified models necessary for shake table testing in the US.

In the unusual "slow motion earthquake" test conducted in late July, UB and Kyoto engineers successfully used the hybrid approach to mimic a landmark, full-scale experiment conducted in 2007 on the E-Defense shake table at the Miki City, Japan, facility.

In that test, a four-story steel building was subjected to a simulation of ground motions that occurred during the 1995 Kobe earthquake.

But, instead of using a full-scale steel building, this time, the researchers developed a hybrid representation of that test by combining experimental techniques carried out in earthquake engineering labs in Buffalo and Kyoto with numerical simulations conducted over the Internet.

The landmark data from the E-Defense test was used to verify the effectiveness of the hybrid approach.

Only the parts of the buildings that were expected to initiate collapse were tested experimentally.

"If this had been a real building, it would have toppled over," said Mosqueda.

That presents a real problem in a laboratory.

"You can't allow a structure to collapse completely on a shake table. You need to have support mechanisms in place, like scaffolds, to catch the falling structure," said Mosqueda.

According to Mosqueda, the hybrid test paves the way for additional experiments that will allow researchers to more precisely learn about the nature of structural collapse.

"We want to know, for example, what is the probability that a building will collapse in the next expected earthquake," he said.

"First, we need to develop this capability to understand and simulate how they collapse. Then, we can determine how to improve new construction or retrofit existing buildings so that they are less likely to collapse," he added. (ANI)