Quake Research to Provide Rare Glimpse of How Structures Collapse

Structural engineers at the University at Buffalo are conducting some of the most comprehensive experiments ever attempted to develop methods of evaluating and designing steel buildings so that they will be less vulnerable to collapse during strong earthquakes.

The experiments are part of a project aimed at both designing new structures that can withstand large deformations without collapsing and at evaluating existing buildings to determine where retrofits may be necessary.

The gap in information about how structures collapse became painfully clear last month after the 7.9 earthquake in Sichuan, China, when the tragic collapse of numerous schools throughout the province caused the deaths of thousands of schoolchildren, the UB researchers noted.

"The whole idea of this project is to find out how much damage a particular building can take before it collapses," said Gilberto Mosqueda, Ph.D., assistant professor in the UB Department of Civil, Structural and Environmental Engineering and principal investigator on the research.

He explained that the philosophy behind building codes is that while buildings may sustain damage in a strong earthquake, they should do so in such a way that the damage can be absorbed by the structure without collapsing so that people can safely evacuate.

"But many different factors besides design come into play, such as the quality of construction, the known seismicity of an area and the magnitude of an event," he continued.

"The problem from the structural side is that there is very little experimental data available to verify our models or assumptions on the nature of how structures collapse because these experiments are very difficult to do in a laboratory," he said.

Mosqueda said that the shake table facility in Miki City, Japan -- the world's largest -- is the only one in the world capable of subjecting full-scale structures to simulated ground motions that can trigger a collapse. Those experiments tend to be expensive in terms of cost, time and labor.

For that reason, Mosqueda has geared his research toward developing more realistic, reliable and economical ways of testing large-scale structures. To do this, his project will combine laboratory experiments of partial structures that can capture the initiation of a collapse either in slow-motion or in real-time with numerical simulations of the remaining full-scale building. This hybrid numerical and experimental model will then be subjected to earthquake loading.

In order to simulate the earthquake loads, the experimental portion of the research will employ high-performance hydraulic actuators that will push and pull elements of the partial structure plus or minus 20 inches at forces of up to 220,000 pounds. Experiments will be performed in UB's Structural Engineering and Earthquake Simulation Laboratory (SEESL) in the School of Engineering and Applied Sciences.

"Through these experiments, we will be able to capture the interaction between a building's elements, such as columns, beams and floor slabs during strong ground motions," Mosqueda said.

Some of those experiments will be conducted over the Internet, with pieces of the same structure simultaneously being tested at UB and Kyoto University, Japan, while numerical simulations will produce data on how the entire structure would perform under the same conditions. These "distributed hybrid tests," as they are called, are made possible by international collaborators and the National Science Foundation's George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) Facility, a nationwide earthquake-engineering "collaboratory" of which UB is a key node.

Mosqueda's project is the result of a prestigious $400,000 Faculty Early Career Development Award he received from the NSF to develop a "Hybrid Simulation Platform for Seismic Performance Evaluation of Structures Through Collapse." According to the NSF, the CAREER program recognizes and supports the early career-development activities of teacher-scholars "who are most likely to become the academic leaders of the 21st century."

Source: University at Buffalo

Related stories:

First glimpse of a key DNA repair protein at work
Repairing breaks in the two strands of the DNA double helix is critical for avoiding cancer. In humans and other organisms, a molecular machine called the MRN complex is responsible for finding and signaling double-strand breaks (DSBs), then launching the error-free method of DNA repair called homologous recombination.
UC San Diego engineers part of nationwide effort to make buildings earthquake safe
Engineering researchers from UC San Diego and the University of Arizona have concluded three months of rigorous earthquake simulation tests on a half-scale three-story structure, and will now begin sifting through their results so they can be used in the future designs of buildings across the nation. The engineers produced a series of earthquake jolts as powerful as magnitude 8.0 on a structure resembling a parking garage.
Researchers crack code of 3-D structure in key metabolic protein
Using X-ray crystallography, researchers at the University of Pittsburgh School of Medicine led by structural biologist Joanne I. Yeh, Ph.D., have become the first to decipher the three-dimensional structure of a membrane-bound enzyme that plays a crucial role in glycerol metabolism – a discovery that could lead to important advances against obesity, diabetes and a potential host of other diseases. Their findings are reported in the March 4 issue of the Proceedings of the National Academy of Sciences.
Collapsing structures to be tested in revamped UW engineering lab
Just as Minneapolis now finds itself in the middle of a national debate on bridge safety, so the Puget Sound area was some 70 years ago. The infamous collapse of the Tacoma Narrows Bridge in 1940 prompted a national discussion on bridge engineering. It also provided the impetus for founding University of Washington's Structural Research Laboratory, which opened its doors in 1948 in the school's department of civil and environmental engineering.
Oldest stars may shed light on dark matter
The universe’s earliest stars may hold clues to the nature of dark matter, the mysterious stuff that makes up most of the universe’s matter but doesn’t interact with light, cosmologists report.
New Dark Matter Candidate Proposed
A vacuum – space essentially void of any matter whatsoever – is a strange thing. And it may be even stranger, according to recent research. Motivated by the results of an experiment known as PVLAS, which showed that not only is the vacuum empty but can act like a crystal under a strong magnetic field, a group of physicists has proposed a dark-matter candidate particle produced during the early universe and within stars.
Folding silicone: building on the microscale
“With classical tools, it is hard to manipulate something so tiny as on the microscale or the nanoscale,” Charlotte Py tells PhysOrg.com. “But here we show how you can use a small drop of water as a micro-wrench to bend planar templates into three-dimensional structures.”
Fluid dynamics theory works on nanoscale outside vacuum
In 2000, Georgia Tech researchers showed that fluid dynamics theory could be modified to work on the nanoscale, albeit in a vacuum. Now, seven years later they've shown that it can be modified to work in the real world, too – that is, outside of a vacuum. The results appear in the February 9 issue of Physical Review Letters.

News discussion:

Technology news