Japan’s Tsunami Debris Offers Wealth of Data
“Engineers should become more involved in research and fundamental knowledge,” says Ian Robertson, a professor of civil engineering at the University of Hawaii at Manoa. In April, he was on the first of seven teams sent by the American Society of Civil Engineers to Japan to analyze the March 11 quake and tsunami. “There is a tendency to just do what’s in the code,” says Robertson, “but in this case the code has been idling. It’s time to bring it up to speed.”
The tsunami team, under leader Gary Chock, president of Martin & Chock Inc., Honolulu, followed up on aerial photos and videos to examine structures that survived. The team took photographs, measurements and rebar and concrete samples for analysis. The data will be used to validate water height, velocity, momentum over land and the impact-force of water and debris.
Validating formulas for calculating impact loads of water-borne debris is of particular interest. Debris loads are a source of tremendous damage but are difficult to test. Calculations also are complicated by the damming effect of the striking objects. The force of the water driving forward adds to the momentum of the debris. Some of the damage is expected to provide clear examples of the pure force of the water pressure and velocity, while other examples likely will generate a new appreciation of the need to consider not only onrushing waves, but the force of the returning seas as well.
