In the wake of the stunning devastation left by the Great East Japan Earthquake and Tohoku Tsunami, there were teetering remains of scattered mangled structures interspersed with standing, unscathed structures.
Japanese and American forensic engineers still are combing the debris and data from the March 11, 2011, earthquake and tsunami to study the forces and suss out how the wounded and surviving structures differ from those that are gone. Now one group, a tsunami loads-and-effects subcommittee sponsored by the American Society of Civil Engineers, is preparing to publish early next year approximately 350 pages filled with engineering analysis and case studies from the debris
The draft monograph carries a hopeful message. “It is quite possible to design buildings and other structures to withstand tsunami events,” the report states. “This is desirable for taller buildings that may serve as refuges, taller buildings that may not be easily evacuated, buildings whose failure may pose a substantial risk to human life, [as well as] essential facilities and critical infrastructure.”
Team leader Gary Chock, president of structural engineers, Martin & Chock Inc., Honolulu, says, “In our own minds, because the damage was so great, we found ourselves—perhaps analogously to some of our predecessors in the aftermath of the 1906 San Francisco earthquake—trying to create a thorough documentation of the structural damage here.”
“It's an excellent report,” says Marc Percher, a senior engineer with The Halcrow Group in Oakland, Calif., who has a draft and is himself the leader of another ASCE tsunami team developing a report on ports and harbors.
“Japan is going to turn into one of the greatest case studies available,” Percher predicts, adding that the tsunami load study, by getting to the physics of the loading phenomenon, will add a significant basis for understanding what happens to infrastructure as the water overwhelms them and the currents continue build. “Determining the current values is very valuable to the entire community,” Percher says.
A Collaborative Beginning
The ASCE is sending a succession of teams to collaborate with Japanese engineers and draw lessons from the event. The first group, dispatched last spring, focused on the forces the tsunami loaded on coastal buildings, bridges, port facilities and coastal protective structures (ENR 5/9 p. 12).
After the initial reconnaissance trip, the ASCE team became aware of a Japanese building damage survey conducted by the Building Research Institute and the National Institute for Land and Infrastructure Management. The groups exchanged data, and the ASCE team's report includes a summary of the Japanese preliminary study. The appendage provides observations that help validate the findings.
The collaborative exchange continues and includes further tsunami data acquisition and research involving 3D LiDAR (light detection and ranging) scanning of damaged buildings (see page 32).