"Wall of Wind" creates Category 5 storm in a lab

Miami, Fla. -- As the 20th anniversary of Hurricane Andrew approaches, Florida International University researchers showed off the first laboratory designed to mimic the power of such a monster Category 5 storm.

Until now, they could simulate the destructive force of storms such as Betsy, the Category 3 hurricane that plowed into Florida and Louisiana in 1965.

The "Wall of Wind" changes that.  It is powered by 12 electric fan-motor units that generate winds of up to 157 mph.

Only three Category 5 hurricanes have struck the continental U.S. in recorded history: the 1935 hurricane in the Florida Keys, Camille in 1965, and Andrew in 1992.

"You look at the pictures, complete devastation," said Erik Salna, associate director of FIU's International Hurricane Research Center.

In a test demonstration Tuesday, an FIU research team placed two small buildings side by side, one with a roof built to the pre-Andrew building codes and the other with today's standards.

In the wake of Andrew, the state of Florida required changes, such as hurricane straps to hold roofs in place, thicker roof sheathings, and even tougher nails.  Shingles, rated to 60 mph before Andrew, must now stand up to winds of 130 mph.

During the test, some of the shingles on the pre-Andrew model were flapping at 50 mph, tropical storm force winds.

The model of the modern building showed its first sign of stress at 96 mph.

Within three minutes of the Cat. 5 force winds, half the roof flew off the pre-Andrew model.

"The plywood sheathing has been ripped off completely," said FIU's James Erwin. "Obviously, that's going to allow rain to get in and all sorts of bad things can happen."

In a separate test earlier this month, researchers said the pre-Andrew model suffered complete failure while taking only Category Two winds.

FIU says commercial clients, which have been limited to Cat. 3 tests, are lining up to have their products pummeled by the Wall of Wind.  They want to know precisely when products will fail and at what wind speeds.

"There's a study out there that any dollar you spend mitigating your home, you save four dollars," said Walter Conklin, a member of the research team.

The Wall of Wind is more than a great, big fan.  Researchers also introduce rain into the equation, sheets of water that often produce the greatest damage in a violent wind event such as Andrew.

"We are going to learn about how things get damaged at high winds and when the exterior elements are damaged," said Arindam Chowdhury, Director of the FIU Laboratory for Wind Engineering.