FOR IMMEDIATE RELEASE
                                                                                                                                   Contact: Jill Andrews  (213) 740-3459, or Denine Hagen  (858) 534-2920  

RESEARCHERS PREVIEW SEISMIC SHAKING TESTS ON A WOODFRAME HOUSE First Comprehensive Study in the United States Will Improve Understanding of Seismic Behavior of Woodframe Construction

SAN DIEGO ­ University of California, San Diego structural engineers, with funding from the $7 million CUREe-Caltech Woodframe Project, are performing earthquake tests on a two-story full-scale woodframe house. A televised demonstration of the fully dynamic shaking test on the house will occur at UC San Diego on April 28. This is the first fully dynamic earthquake test ever performed on a full-scale woodframe building in the United States.

The house, constructed on an earthquake simulation platform or "shake table" inside one of UCSD's Department of Structural Engineering laboratory buildings, will be subjected to ground motions that were recorded during the 1994 Northridge earthquake near Los Angeles. The house is based on common design practices in California and is complete with a tile roof and several rooms upstairs and down. Information from 300 sensors on the building will be used to create computer models to aid in evaluating new technologies and design methods.

Opening remarks will be made by Dallas Jones, director, Governor's Office of Emergency Services and Mike Mahoney, Federal Emergency Management Agency (Mitigation Directorate, National Earthquake Program), representing the two main funding agencies of the project; CUREe-Caltech Woodframe Project Manager Prof. John F. Hall (Caltech), and CUREe Managers for Testing and Analysis Frieder Seible and André Filiatrault (Professors of Structural Engineering, UCSD), who will describe the activities and goals of the Woodframe Project, and answer questions about the dynamic earthquake test.

Invited viewers of the event, which marks the culmination of California's Earthquake Preparedness Month, are limited to reporters and project researchers and guests of UC San Diego and CUREe. However, to accommodate public interest, information about the project and video clips will be available via the Internet at: www.curee.org

CUREe (California Universities for Research in Earthquake Engineering), a non-profit organization that represents a consortium of universities with major earthquake engineering programs, is managing the three-year woodframe project under the direction of Professor John Hall (Caltech). Over two dozen universities and numerous consulting engineers are involved in the project, aimed at developing reliable and economical ways of improving woodframe building performance in earthquakes. "Very few numerical models capable of analyzing the seismic behavior of 3-D woodframe structures exist ­ and our understanding of how a wood structure as a whole system is very limited," stated Hall. The project, funded mainly by the Federal Emergency Management Agency (FEMA) through a grant administered by the California Governor's Office of Emergency Services (OES), was proposed after the Northridge event when more than $20 billion in property damage occurred to woodframe homes. Twenty-five people died because of building damage in that earthquake, and all but one of the fatalities occurred in this kind of construction. 

The impact of the project could be enormous. "Although 99% of residences and many schools and commercial buildings in California are wood, commonly referred to as '2x4' construction, there has been very little research focused on improving earthquake resistance," stated project director and CUREe executive director Robert Reitherman. "Throughout the United States, over 80 percent of buildings are built of wood." Laboratory testing and analysis of both residential and non-residential woodframe buildings and studies of their damage in the Northridge earthquake will be used to improve building codes and standards, make insurance ratings and loss estimates more accurate, and train practitioners in the design and construction industry. Project spokesperson Jill Andrews, public information manager for the project and director for education and outreach at the Southern California Earthquake Center, said "Videotape footage of tests such as these will be used in programs for the general public and in specialized training for engineers, architects and building contractors."

The principal investigators of the Testing and Analysis element, André Filiatrault, Frieder Seible and Chia-Ming Uang (Professors and Associate Professor, UC San Diego, respectively), believe that the level of confidence associated with the seismic analysis and design of woodframe construction is much lower than for concrete or steel construction. "There is a need for more test data on complete full-scale woodframe structures to improve the understanding of the state-of-the-art and the state-of-practice of analysis and design," stated Seible. "The low weight-to-strength ratio of wood structures and the availability of high performance shake tables has indicated that shake table tests appear to be the most attractive procedure for system testing." The goals of the shake table testing of the house are intended to provide data for use in other woodframe project activities, such as development of analytic tools, integration of results from other tests, and recommendations for code changes. "To maximize the information to be gathered and learned, multiple tests are being conducted at various stages of completion of the house. Our primary objective is to measure and quantify the building's dynamic characteristics and its responses, and to document how the distribution of forces within the building may change as we change its configurations," said Filiatrault. "Another objective is to learn more about the relationship between ground motion and damage and repair costs, and to provide data for defining more realistic performance objectives. The shake tests will also provide calibration for the project's other individual component and full-scale building tests and resulting models."

The tests are being conducted on the uniaxial earthquake simulation system at UC San Diego, which features a 4.8-ton shake table of all-welded steel construction. An advanced control system allows the reproduction of earthquake ground motions with high fidelity. Multiple shake tests are being conducted at various stages of construction of the house. Simulated ground motions will test the house to see if it can attain performance from virtually earthquake-proof to near-collapse.

The two-year testing and analysis plan is to conduct two additional shake table projects: 1) tests of a full-scale multi-story apartment building with tuck-under parking garages at UC Berkeley, and 2) tests of a simplified box-type woodframe building model at the University of British Columbia, Canada. Woodframe project researchers are also sharing experimentation results with researchers in New Zealand and Japan.