During a tsunami, water isn’t the only problem structures in its wake face. There’s also the debris being carried by the massive waves. One such piece of debris that has proved especially problematic are cargo containers that, when fully loaded, weigh in at 60,000 pounds, reports Science Daily.
“These shipping containers are surprisingly ubiquitous,” Ronald Riggs Riggs, a structural engineer at the University of Hawaii, told Science Daily. “They may have been moving only about 10 miles an hour, but given their weight, this is a significant load for a structure not made for it.”
This type of debris makes for a great unknown for structural engineers when designing the best storm-proof houses and structures they can. So Riggs set out to determine just what kind of impact debris like cargo containers can have, Science Daily reported.
Riggs led a multi-university team in the effort which would benefit not only those in tsunami-prone areas seeking shelter in sturdy buildings, but also coastline storage tanks which hold chemicals and other pollutants.
Using a site at Lehigh University and another at Oregon State University, Riggs and his team swung full-scale wooden telephone poles and cargo containers on a pendulum to determine the force of impact at several speeds.
Riggs was suprised to find that being submerged in the water did not increase the load of the containers. He was also surprised to find that the weight of the containers contents did not increase the impact as much as expected. The impact of a fully-loaded container did not differ greatly from that of an empty one.
Riggs will use these findings to help develop better building guidelines in the future. He will present the findings at the 32nd International Conference on Ocean, Offshore and Arctic Engineering, in France in June.