Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seismic shock absorbers for woodframe houses

21.06.2006
Earthquake simulation to test new damping system in full-scale townhouse

As part of a major international project to design more earthquake-resistant woodframe buildings, an engineer from Rensselaer Polytechnic Institute will be testing a damping system designed to act as a seismic shock absorber. The dampers, which have never been tested before in wood construction, will be installed inside the walls of a full-scale, 1,800-square-foot townhouse -- the world's largest wooden structure to undergo seismic testing on a shake table.

The unprecedented testing is part of a $1.24 million international project called NEESWood, funded by the National Science Foundation through its George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) program. The goal of NEESWood is to safely increase the height of woodframe buildings in active seismic zones through the development of a design approach that considers a wide range of performance levels -- from completely undamaged to almost collapsing.

The height of woodframe buildings traditionally has been limited to about four stories, mainly due to a lack of understanding of how taller structures might respond to earthquakes and other natural disasters. "We don't have accurate physical data to fully define how wood structures behave in earthquakes," said Michael Symans, associate professor of civil and environmental engineering at Rensselaer. "We have some models, but their accuracy has not been verified with full-scale test data. This experiment will help us to further evaluate and refine those models."

Symans will be supervising the damping tests at the University at Buffalo's Structural Engineering and Earthquake Simulation Laboratory (SEESL), which is home to two adjacent three-dimensional shake tables where the test structure is anchored.

On July 6, a demonstration of the damper test will be open to the media, as well as broadcast live on the Web at http://nees.buffalo.edu/projects/NEESWood/video.asp.

One approach to limiting the damage in woodframe structures is to look at the problem from an energy point of view, according to Symans. In an earthquake, the shaking ground imparts a certain amount of energy into the structure -- energy that must eventually be dissipated. During the earthquake, some of the energy is transformed to kinetic energy -- moving a building from side to side -- or to strain energy, in which the structural framing system becomes so deformed that it can be permanently damaged or even collapse. The goal of the dampers is to absorb a large portion of the earthquake energy, much like shock absorbers in a car absorb bumps in the road.

The damping system is essentially made up of fluid-filled shock absorbers installed horizontally throughout the walls of the house. "If we can channel some of the energy into the dampers, we can reduce the strain energy demand and thus reduce damage to the structure," Symans said. The damping technology has been applied to steel and concrete buildings, but never before to wood structures. For the NEESWood experiment, the fluid dampers are being donated by Taylor Devices Inc., of North Tonawanda, N.Y.

"For the longest time, building codes have been prescriptive -- the designer is told what to do to meet certain specifications, without explicit consideration given to the expected performance," Symans said. But lately there has been a shift in thinking as more large earthquakes have hit high-population areas. About half of the approximately $40 billion in loss caused by the 1994 Northridge earthquake in the Los Angeles region was associated with wood structures, Symans notes, and this was much more damage than the general public expected. "The perception among building owners and the general public is that if a structure is built according to code, it will perform well during an earthquake," he said. "This is true of snow, rain, and other typical severe weather conditions, but not necessarily for hurricanes and earthquakes."

Previous large-scale shake table tests have been performed on simple, box-like structures, but the NEESWood Project involves testing of a much more realistic building, Symans said. The townhouse in this experiment has balconies, an atrium, and other defining features that are more likely to be in the floor plan of a real woodframe residential building. As the testing progresses, the team will be adding finish materials to the building, culminating in November with the violent shaking of the furnished, three-bedroom, two-bathroom townhouse -- mimicking what an earthquake that occurs only once every 2,500 years would generate, according to Symans.

Phase 1 will be a benchmark test of the "bare bones" structure. Phase 2 will test the dampers on this benchmark building, and then finish materials will be added for each additional phase to test how these affect the response of the structure. Each phase will be run at increasingly higher levels of shaking, designed to simulate the increasing intensities that were recorded during the Northridge earthquake.

Jason Gorss | EurekAlert!
Further information:
http://www.rpi.edu

More articles from Earth Sciences:

nachricht Colorado River's connection with the ocean was a punctuated affair
16.11.2017 | University of Oregon

nachricht Researchers create largest, longest multiphysics earthquake simulation to date
14.11.2017 | Gauss Centre for Supercomputing

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>