OREGON STATE UNIVERSITY

Wave Tests Measure Forces of Hurricane Flooding

12/12/2007

CORVALLIS, Ore. – It’s flood season in the Pacific Northwest, and one house is being particularly hard-hit – large waves are lapping at its door, over and over again.

This modest wood-frame structure, however, is at the Hinsdale Wave Research Laboratory at Oregon State University, only about three feet high, and can be rebuilt after it collapses, time after time.

From it, experts are learning much about just what happens when a structure is battered repeatedly by waves, especially the type found in hurricane storm surges. At some point in the future, that knowledge may translate into better building codes or improved construction standards that could reduce both the physical damage and loss of life from these catastrophic events.

“When we toured the areas near the beaches that suffered the most damage from Hurricane Katrina, it was apparent that much of the greatest physical damage came not from the wind but from the storm surge,” said Rakesh Gupta, a professor of wood science and engineering in the OSU College of Forestry. “These waves are very powerful, and most wood structures simply can’t resist those kinds of forces.”

In the end, Gupta said, it may never be economical and practical to build wood structures capable of withstanding a 10-20 foot wall of water driven by a hurricane. But that’s not a foregone conclusion, he said, and researchers will only know the possibilities once the data is all processed. Improved building concepts may go a long way toward reduce storm-surge damage to all types of buildings, he pointed out.

The storm surge from Hurricane Katrina in some places came inland almost a mile, causing enormous damage. Storm surges from hurricanes or other major storm events can vary greatly depending on the severity of the storm, topography, wind speeds, barriers, tide levels and many other factors.

“We have a fairly good understanding of the forces on homes caused by conventional flooding, but not these more powerful storm surges,” Gupta said. “In this study, we’re measuring those forces very carefully, how they are being transferred, and will be able to use that data to consider different construction approaches.”

On the small model, four sensors determine loads on the structure and one measures the amount of deflection. The research, done by the Hurricane Katrina Woodframe Damage Assessment Team, is funded by the National Science Foundation, one part of larger efforts to understand and reduce building damage from severe weather events.

Gupta, an expert in timber engineering and mechanics, has done related work in understanding the forces on structures from earthquakes, windstorms, and other issues.

Editor’s Note: Gupta and graduate student Jebediah Wilson will continue their tests on the wood frame home in one of the wave basins at the Hinsdale Wave Research Laboratory on Thursday and Friday of this week. Media interested in still or video photography can contact Gupta directly during that period at cell phone 541-760-8786.