University at Buffalo - The State University of New York

Published: October 18, 2007

By ELLEN GOLDBAUM
Contributing Editor

To learn more about how whole buildings move during earthquakes, engineers test models of them on powerful shake tables precisely calibrated to deliver the shock and rumble of historic ground temblors.

A "patient" in a two-story, life-sized replica of a fully equipped composite hospital room falls off a bed during the inaugural demonstration of the new Nonstructural Components Simulator.
PHOTO: DOUGLAS LEVERE

Researchers have long wished for an equivalent testing method to simulate how architectural, mechanical, electrical and plumbing/piping systems, as well as building contents, are impacted during earthquakes, especially in critical facilities like hospitals.

Now they have one.

A new testing facility at UB and MCEER is the world's first test apparatus specifically designed to subject costly equipment and mechanical systems in hospitals and other important structures to the precise floor vibrations that they experience during the strongest earthquakes.

The new Nonstructural Components Simulator (NCS) in UB's Structural Engineering and Earthquake Simulation Laboratory (SEESL) on Friday underwent its inaugural demonstration, reproducing full-scale earthquake vibrations in real-time on a two-story, life-sized replica of a fully equipped composite hospital room.

"No other facility in the world has this capacity at present," said Gilberto Mosqueda, assistant professor of civil, structural and environmental engineering in the School of Engineering and Applied Sciences and lead designer and builder of the facility with Rodrigo Retamales, a doctoral student in the same department.

The NCS features a two-story-high, four-column, swivel test frame supporting two steel-grid platforms, which together represent two adjacent floor levels in a building. The system replicates two upper levels of a multi-story building through the use of four high-performance hydraulic actuators that push and pull the platforms up to 40 inches in each direction, at velocities of 100 inches per second, simulating in real-time how upper floors move during earthquakes.

"The complete apparatus is capable of simultaneously reproducing these very large and fast motions at two different floor levels in real-time, allowing for very precise examination of the impact of vibrations on building content and equipment during the strongest earthquakes," said Mosqueda.

The launch of the NCS comes as sweeping changes affect building codes nationwide and a new California law challenges hospitals to secure "nonstructural components." These include everything that is permanently attached to the building, but not part of its skeletal structure, such as electrical and mechanical equipment, piping, wall partitions, computer installations and, in hospitals, all medical, diagnostic and surgical equipment.

Industry representatives attending a symposium held Friday at UB on "Seismic Regulations and Challenges for Protecting Building Equipment, Components and Operations" shared their experiences on how they address code requirements for various "nonstructural" systems. Attendees learned how the new UB facility may be able to help them qualify the equipment and systems they manufacture according to new International Building Code regulations. Information on the symposium is available at their Web site.

Mosqueda said the facility will enable UB and MCEER researchers and government and industry partners to reproduce full-scale floor motions to better understand, quantify and control seismic response of very costly equipment.

The new facility also provides engineers with the opportunity to compare an earthquake's impact on nonstructural components in different types of structures.

That's critical, earthquake engineers say, especially in light of the California legislation.

California's Senate Bill 1953 requires that by the year 2030, acute care medical facilities must remain fully functional after an earthquake.

Both the California legislation and the building code changes signal a major shift in how structural engineers, architects and other professionals go about protecting new and existing construction projects from earthquake damage.

"Engineers must look beyond structural issues and give thought to how building contents may shift about, suffer or cause damage or inflict injury," said Andre Filiatrault, professor of civil, structural and environmental engineering and director of SEESL. "They must also consider the economic issue of business disruption when such systems and/or equipment fail in an earthquake. This is extremely critical in the case of hospitals."

MCEER is especially well suited to studying these issues, said Filiatrault, since a substantial part of its work has focused on mitigating seismic damage to hospital buildings, where nonstructural components represent more than 90 percent of an owner's investment.

"More and more, we are seeing buildings survive earthquakes without collapse, but they still suffer business disruption due to major nonstructural damage," Filiatrault said.

The work he and his colleagues are undertaking with the new NCS is designed to keep buildings functional, especially hospitals and acute-care facilities, the services most critical to initial post-earthquake response and recovery.

"Nonstructural components are very complex and fairly difficult to model and analyze," explained Andrei Reinhorn, Clifford C. Furnas Professor of Structural Engineering and former SEESL director.

"We had done some testing of various nonstructural components with our existing advanced equipment, but found we needed a special testing facility to accurately understand and assess them," he said.

In part, that's because nonstructural components inside buildings are not subjected to ground motions, but rather to the building's motions, which are an amplified version of the ground motions.

"A roof is going to move a lot more than the ground floor," noted Filiatrault. "Similarly, a PET scanner or an MRI machine located on the upper floor of a hospital is going to experience far more shaking than equipment on the ground floor."

Now that the NCS is operational, manufacturers and property owners are invited to take advantage of UB's facility to test their products.

Design and construction of the NCS was funded with a $260,000 National Science Foundation supplemental grant to the original $11.2 million award in 2004, which made SEESL a leading node in the George E. Brown Jr. Network of Earthquake Engineering Simulation (NEES), a nationwide earthquake-engineering "collaboratory." Total cost of the UB SEESL/NEES upgrade was $21.2 million.

"This capstone addition to what is recognized as the most versatile earthquake-engineering testing facility will allow us to validate and greatly expand the knowledge generated over the past decade through NSF-funded MCEER research activities to achieve seismic-resilient hospitals," said Michel Bruneau, director of MCEER and professor of civil, structural and environmental engineering.

Mitigation and response to extreme events, whether manmade like terrorist attacks or natural events like earthquakes and hurricanes, is a research strategic strength identified in the UB 2020 strategic plan being implemented by the university.

The UB-NEES site, MCEER and the Department of Civil, Structural and Environmental Engineering co-sponsored Friday's symposium and the NCS dedication/demonstration.

Additional information on the NCS is available at their Web site.