6-Story Wood-Framed Condo Building Subject of World's Largest Full-Scale Earthquake Simulation Test

According to the homepage of the National Science Foundation's (NSF) Network for Earthquake Engineering Simulation wood-frame structure project (NEESWood):

On July 14th, [2009] a six-story condominium building shook with the earthquake motions of the 1994 Northridge quake, but one and a half times as intense--more powerful than any quake California has experienced in modern times.

The final experiment of NSF's multi-year NEESWood project, the effort tested new ways to construct buildings that can withstand severe forces of nature.

NEESWood set out in 2005 to study how wood-frame structures--those consisting of mostly wooden parts, as opposed to concrete and steel--respond to the shaking of earthquakes. Wood-frame construction can be more affordable for mid-rise buildings than other methods, but little is known about how such buildings respond to earthquakes.

Using the 1988 Uniform Building Code as a guide for construction, the project engineers used the resulting test data to develop computer models that may help designers predict how woodframe buildings will fare in an earthquake.

The recent testing by the National Science Foundation of a six story wood framed structure highlights the overall performance of wood framed structures in earthquakes. These structures possess great strength to weight characteristics and flexibility, both of which allow favorable performance in seismic events. The tests were performed at the types of magnitudes which only occur rarely in California and Japan. The testing may result in revisions to current height limits in the model codes for wood structures.

The only drawbacks to the testing were the lack of finishes such as light weight concrete on floors or drywall which impose significant additional weight on the structure without imparting substantial additional strength. Additionally the tested design relied on simple shapes and limited openings in its tested form, both of which would impose limits on designers in the United States. Nevertheless, tests such as these should form the basis for future model codes and evaluation of wooden structures in existence today.

Below is the video of the test on July 14 as well as extensive commentary from some of the people behind the testing:

To summarize, this project involved the construction of a wood-framed six-story condominium consisting of 23 one and two bedroom units above a concrete and steel commercial first story. This structure was placed upon the very large "shake table" housed in the earthquake testing facility at Japan's Hyogo Earthquake Engineering Research Center, known as E-Defense. A series of tests were conducted utilizing a plethora of high-tech sensors. The tests were conducted in simulation of earthquakes up to a 7.5 magnitude, to date the largest full-scale earthquake simulation ever. By comparison, the Northridge earthquake in 1994 measured 6.7 on the Richter scale. The post-testing data will take weeks to analyze but initial results seem promising, according to John van de Lindt, principal investigator on the test and civil engineering professor at Colorado State University, in a press release by corporate sponsor, Simpson Strong-Tie:

"Early results of the testing this summer show that the building performed so well and had so little damage that it validated the design philosophy developed by Colorado State, other universities in the National Science Foundation's Network for Earthquake Engineering Simulation and our industry collaborators," said van de Lindt.

Below are some photos taken from the project. For more information about the photos see the info at Colorado State University Engineering's Capstone Test summary. Additional photos can be found at Steve Pryor's pics from the NEESWood project.

Shake Table at E-Defense Bird's Eye ViewActuators for the world's largest shake tableBuilding in place on shake tableReady for testing

Tom Jenkins, AIA