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The Federal Highway Administration has mandated that, beginning in October, all state highway projects must use a construction code called LRFD (Load Resistance Factor Design), which is based on the concept of Reliability Based Design (RBD), a procedure that Prof. Sam Paikowsky has been researching and lecturing on since 1999.
“RBD has been on the books of the American Association of State Highway Transportation Officials (AASHTO) since 1996 but it hasn’t been mandatory,” says the professor of civil and environmental engineering.
The old design method, called Working Stress Design, which uses safety factors unassociated with quantified risk, has been the common practice for more than a century.
“Although RBD had been on the books for some time, engineers didn’t use it, didn’t know how to use it,” Paikowsky says. “They were afraid of it. But it’s a much more intelligent design. It’s a live design, meaning that as you gain more knowledge, you improve the design. So, as time passes, it’s the kind of design that will be improved with future experience and knowledge.
“RBD isn’t complex although engineers tend to think it is,” Paikowsky says. “When engineers have used certain design procedures their whole lives, it’s difficult to get them to move to a completely different method. It’s an adjustment issue and an education issue.
“The whole world is moving to the same risk and reliability-based design. When I gave a keynote lecture on the topic at a conference in Japan in 2000, I realized that we could use the expertise that existed in other countries. So I established close collaboration with research groups all around the world, especially in Japan, Germany and Hong Kong. The Japanese had experience in risk-based design because of their earthquake problems. Following a close collaboration with the Japanese over the past eight years, we have invited Dr. Shailendra Amatya of the University of Gifu to join us for the next two years as a post doctoral fellow on a research project. Another collaborator on the same project is a doctor of engineering at Essen University in Germany, Kerstin Lesny, who had been dealing with certain aspects of foundations that we were missing.”
Paikowsky has been conducting research on this topic with the aid of eight grants, five of them totaling about $1.5 million. They were awarded over the past seven years with the support of the National Cooperative Highway Research Program, via the National Academy of Science. The funding ultimately comes from gasoline taxes in all 50 states.
Paikowsky will be lecturing during the summer at four universities in Germany and one in Holland as well as at the annual AASHTO bridge conference.