Beijing
Room 1507, Kuntai
International Mansion,
No.12 B Chaowai Street,
Beijing 100020
Tel: 86-10-59251256
Fax: 86-10-59251259
 
FII China Email: info@bcfii.cn

Wood-frame construction has benefited from many research projects ranging from tests on the smallest nail to full-scale earthquake simulations on whole houses. The observed seismic performance of traditional wood-frame construction is difficult to model mathematically due to the many load paths and contributions of “non-structural” elements. By gaining a better understanding of the properties of materials and assemblies, researchers are better able to predict the performance of whole houses. Full-scale assemblies are being used to develop sophisticated models of how a whole house works together to resist earthquake loads. This research helps to explain the performance of conventional wood construction and can be used to provide more effective design solutions.

FPinnovations – Forintek is Canada’s foremost wood research institute and has an ongoing multiphase seismic research program focusing on component testing and modeling. Results from their research were used to augment the seismic provisions in the Canadian wood design standard. FPinnovations - Forintek and its research partners have also worked on computer models used to evaluate the performance of wood-frame buildings in earthquakes and this work shows promise as a tool that can help to efficiently design earthquake-resistant wood-frame buildings.

Tests on full-scale wood-frame buildings were undertaken as early as 1965. Since then, there have been other tests at research institutions around the world. The more recent tests involve using a “shake table” to closely simulate the effects of a real earthquake. Of particular interest there is the CUREE project in California. A parallel research project was carried out at the University of British Columbia (UBC).

The Consortium of Universities for Research in Earthquake Engineering (CUREE) (www.curee.org) is a non-profit organization, established in 1988, to advance earthquake engineering research, education and implementation. The project is funded by the US Federal Emergency Management Agency (FEMA) through a grant administered by the California Governors Office of Emergency Services. The CUREE-Caltech Woodframe Project has five components; testing and analysis, field investigations, building codes and standards, economic aspects, and education and research.

The project included full-scale shake tests that involved the construction of a house on a special platform capable of simulating earthquake loads of different magnitudes. Three different shake table projects were conducted: tests of a simplified full-scale two-storey single family house (University of California San Diego), tests of a full-scale multi-storey apartment building (University of California Berkeley) with tuck-under parking garages, and tests of a simplified box-type wood frame building (UBC).

The two-storey house tests included specimens simulating a conventionally framed house and engineered houses. Some specimens were built without finishing materials (bare), and others were finished with stucco. All specimens were subject to 0.89g ground accelerations. A review of the test results by Canadian researchers led to the following general observations:
-In all projects, none of the specimens built with finishes (i.e. stucco) reached a “near collapse” state.
-None of the two-storey “bare” specimens tested in the CUREE project reached a “near collapse” state.
-One three-storey “bare, tuck under garage” specimens tested in the CUREE project reached a “near-collapse” state.
-Test results are in substantial agreement with previous surveys of the performance of wood-frame construction.
-The amount of deflection increases with the degree of openings in the walls.
-Deflection in the conventionally constructed house was higher than deflections in the comparable engineered house.
-Adding a stucco exterior finish and gypsum wallboard interior finishes significantly reduces the lateral deflection, reducing the damage to the finished structure substantially.

The CUREE tests at the University of California San Diego and Berkeley, and tests performed at UBC and FPinnovations have produced many pertinent results that can be applied to the seismic design of North American style wood-frame buildings.

The amount and quality of research devoted to wood-frame construction around the world means an increasing ability to understand how earthquakes affect wood structures and how to design them to perform even better.

[Back]