Straw house design used in Pakistan withstands violent shaking at quake lab

April 4th, 2009 - 3:44 pm ICT by ANI  

Washington, April 4 (ANI): An innovative straw house design used in Pakistan by an engineer has withstood an earthquake-simulation shake table that involved violent shaking.

The full-scale, 14-by-14-foot straw house, complete with gravel foundation and clay plaster walls, was built by University of Nevada, Reno alumna and civil engineer Darcey Donovan.

It was subjected to 200 percent more acceleration/shaking than was recorded at the 1994 Northridge, California earthquake, the largest measured ground acceleration in the world.

After a series of seven increasingly forceful tests, in the final powerful test the house shook and swayed violently, cracked at the seams and sent out a small cloud of dust and straw, and remained standing.

Donovan oversaw the successful series of seismic tests run at the University’s Large-Scale Structures Laboratory.

She was testing her innovative design for straw bale houses she has been building since 2006 throughout the northwest frontier provinces of Pakistan, in the foothills of the Himalayas between Pakistani tribal areas and Kashmir.

Her design uses bales as structural and load-bearing components rather than just insulation as in other straw-bale designs.

“We’re very pleased with the results,” said Donovan. “The house performed exceptionally well and survived 0.82g (0.82 times the acceleration of gravity) and twice the acceleration of the Northridge quake,” she added.

The Geological Survey of Pakistan estimates the 2005 Kashmir earthquake to have had peak ground accelerations in the range of 0.3 to 0.6g.

Most people were killed and injured in that October 2005 earthquake as they slept when their poorly built houses collapsed on top of them.

The magnitude 7.6 earthquake killed 100,000 people and left 3.3 million homeless or living in tents.

“Our goal is to get the largest number of poor people into earthquake-safe homes. We want to make it as affordable as possible so they build a safe home. We want to save lives,” said Donovan.

According to Donovan, “Straw bale houses are used around the world, but those have posts and beams for support and rely on energy-intensive materials, skilled labor and complex machinery, making it unaffordable for the poor.”

“In our design, the straw bales are the support, and not just for insulation. Our design is half the cost of conventional earthquake-safe construction in Pakistan. The materials we use - clay soil, straw and gravel - are readily available; and we utilize unskilled labor in the construction,” she explained.

The earthquake-safe buildings are 80 percent more energy efficient than modern conventional buildings at 50 percent of the cost.

“Our system is different than anything ever tested,” said Donovan. (ANI)

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