Poor construction of older homes in the Gulf Coast region contributed to the severity of the damage caused by Hurricane Katrina’s winds, according to a preliminary report issued by a Colorado State University professor and a team of engineers from around the country.
John van de Lindt, civil engineering professor at Colorado State University, served as the principal investigator on the project, which was funded by the National Science Foundation.
"I volunteered after I gave to the Red Cross in the wake of Katrina and wanted to do more," van de Lindt said of the study.
Hurricane Katrina became the most destructive storm on record after making landfall in southeast Louisiana as a Category 4 storm and devastating the Louisiana, Mississippi and Alabama coastlines. The storm and its aftermath killed more than 1,000 people in Louisiana alone.
Older homes studied by van de Lindt’s team were built with conventional construction methods and performed poorly under hurricane-force winds, which led to significant structural and non-structural damage, the report said. The majority of homes studied were within five miles of Interstate 10 along the Mississippi Gulf Coast in such areas as Gulfport and Biloxi, Miss.
"We hope this information can help decision-makers in the Gulf Coast region and stress the importance of paying attention to design codes and standards," van de Lindt said.
Researchers visited the coast for five days in late September. Other participants in the study are Kenneth J. Fridley and Andrew J. Graettinger, University of Alabama; Rakesh Gupta, Oregon State University; Steven E. Pryor, Simpson Strong Tie; and Thomas D. Skaggs, APA-The Engineered Wood Association.
Highlights of the study:
– Wind uplift load path was not consistently provided, resulting in structural failure.
– Support columns under porch overhangs and in carports were not anchored into concrete.
– Nail spacing did not meet code minimums particularly in roof sheathing, resulting in loss of roof sheathing and allowing water into roofs.
– Homes that followed design codes and newer homes performed well, suggesting effectiveness of design code revisions adopted in 1992 after Hurricane Andrew.
– Small details – such as a lack of nails in hurricane clips – were not addressed.
The committee plans to submit a final report that includes 27 case studies – from single-family homes to entire subdivisions – to the National Science Foundation, van de Lindt said. For more information, visit the project Web page at http://www.engr.colostate.edu/~jwv/hurricane-Katrina-woodframe.htm.
Van de Lindt joined Colorado State in July 2004. Previously, he worked as an assistant professor at Michigan Technological University. He obtained his master’s and doctoral degrees from Texas A&M University in 1995 and 1999, respectively.
Van de Lindt recently received a four-year, $1.24 million grant from the National Science Foundation to develop a new design approach for taller woodframe buildings in earthquake-prone areas. He’s also working under an NSF grant with Bogusz Bienkiewicz, a wind engineering professor in Colorado State’s civil engineering department, to connect a state-of-the-art wind tunnel with a large structural load frame to simulate the effect of wind on structures. This connection will be in "real time" over the Internet 2 backbone – a faster Internet used primarily for research purposes.