Materials tested for building hurricane-proof safe rooms

An air-powered cannon sent timbers barreling through wooden walls at the Civil Defense’s test facility in Diamond Head Crater yesterday as engineers began research on next-generation building materials to protect Hawaii’s houses from hurricanes.

The tests, which will continue for the next year, will guide island contractors as they implement new state building codes that require houses to be equipped with hurricane-proof safe rooms. Tests on wind-resistant materials for the rooms are being conducted by the state Civil Defense in conjunction with University of Hawaii engineering professor Ian Robertson and structural engineer Gary Chock.

"We’re enabling a quicker, more efficient implementation by industry," Chock said.

New building codes, drafted by the state’s Building Code Council and approved by the governor in April, require all new houses to be equipped with safe rooms to shelter people from flying debris and strong winds. Chock said the continuing research will help contractors determine which materials and kinds of wall construction meet the stricter hurricane safety standards without costing too much.

"What we’re doing is trying to improve hurricane safety … not at exorbitant cost, but still providing the means for sheltering in place," Chock said.

The 20-foot-long air-powered cannon — what Robertson calls an "oversized potato shooter" — blasts 9-foot-long two-by-fours out of a PVC barrel at up to 80 mph.

During yesterday’s testing the lumber was shot at 34 mph to simulate hurricane conditions. Although hurricane winds can top 100 mph in Hawaii, Robertson said debris generally travels at one-third the speed of the wind.

"The hope is that we can develop products that are Hawaii specific," Robertson said.

The cannon was built in 2005 by Robertson and doctoral candidate Anindya Sengupta in the University of Hawaii’s Department of Civil and Environmental Engineering with $450,000 from the state Legislature. The wind cannon is one of just five in the nation and is closely based on a prototype built by Texas Tech to simulate tornadoes.

The cannon will be kept by state Civil Defense in a National Guard warehouse in Diamond Head Crater. The state will eventually use its findings from the building materials and safe-room design testing to augment the Hawaii building code.

"Bottom line is giving people a safe place to go during a hurricane," Robertson said. "If they don’t have these components, then they need to evacuate."

Although the National Weather Service forecasts a calmer-than-usual hurricane season this year, Civil Defense will be making a major push in September — Hurricane Preparedness Month — to educate residents on hurricane safety. Hurricane season in the Central Pacific runs from June 1 to Nov. 30.

"It doesn’t matter if the prediction is one, 10 or 20 (hurricanes)," said Civil Defense hurricane planner Danny Tengan. "It only takes one."

Tengan said that because the state does not have enough shelter space to accommodate everyone, residents should look try to create safe rooms in their homes. Even if houses are not yet equipped with hurricane-proof materials, Tengan said families can create safe spaces by reinforcing indoor closets and bathrooms with plywood during a storm.

"You’ve got to realize how to shelter in place," Tengan said. "Do not just wait for government to come to you. You have to start doing your own planning."