Earthquake bale out
Straw bale construction resists shaky ground in Pakistan and Reno
Combine a lot of people, poor construction, and shaking ground, and you have a disaster. “Remove one of those elements, and there is no disaster,” said John Anderson, director of the Nevada Seismological Laboratory at the University of Nevada, Reno.
Through the introduction of straw bale construction, structural engineer Darcey Donovan is trying to prevent the kind of devastation northern Pakistan saw in 2005, when a 7.6 magnitude earthquake killed more than 100,000 people and left more than three million homeless. Donovan had been focusing on straw bale construction with her business EcoEngineering when the earthquake in Pakistan hit. “When I read about the earthquake, I realized it was the perfect solution for them,” she said.
What began as a volunteer experience on a pilot program for straw bale construction in Pakistan evolved into her organization, Pakistan Straw Bale and Appropriate Building (PAKSBAB), which was founded in 2006. The UNR alum and Truckee resident is now developing earthquake-resistant straw bale building methods that are affordable, use locally-sourced materials and are energy efficient, and implementing those methods in Pakistan.
Most homes in Pakistan are built with either stone and mud mortar, or with concrete, neither of which does well in an earthquake. With Donovan’s special straw bale design, bales of straw are built into the walls of the home, providing structure and insulation—at about half the cost of other earthquake-safe building methods in Pakistan.
Just how much shaking can these straw bale buildings take? That’s what a shake test attempted to find out at UNR’s Network for Earthquake Engineering Simulation (NEES) building last week. PAKSBAB built a 14-by-14-foot straw bale home model and mounted it atop the shake table. They then conducted a series of tests that first shook the home at 50 percent of the levels of the Northridge earthquake, a 6.7 magnitude quake that occurred in California in 1994. Then they turned it up to 75 percent, then 100 percent, then 125, 150. “I hope we destroy the building,” said Donovan between tests. “We really want to understand how far we can go with this.”
Slowly, a crack opened here, a chip of wall fell off there, a clump of straw dropped from the ceiling beams, until at 200 percent, the home was deemed uninhabitable, far surpassing their expectations.
Donovan hopes the data will help convince more donors and Pakistan’s Earthquake Reconstruction and Rehabilitation Authority that this technology is sound and worthy of support. The group would like to build the structures in other earthquake-prone areas of the region, too, such as India and Nepal.
And while there aren’t many straw bale homes built in Reno, Donovan says the system they’re developing could be applicable throughout the world. “This building method could very well be applied to the Reno area,” she said. “It’s an inexpensive building method. We have our share of poor people in our country, as well, and we could give them much better homes. These homes are earthquake safe, energy efficient, use natural, nontoxic materials and we could involve the owners in the project. This exact same idea could be implemented in the U.S.”