The aftermath of the recent earthquake in Japan will forever be etched in our minds. What made this natural phenomenon deadlier is the tsunami that accompanied it. Tsunamis are common in seismic regions surrounding the Pacific especially those located near the “Ring of Fire”.
Videos posted on the internet as well as those we saw from different newscasts, showed buildings, houses, boats, vehicles, bridges, trees, etc. being carried away, tossed and eventually destroyed by the powerful waves of the tsunami. What are tsunamis and can prefabricated metal buildings be designed to withstand tsunamis?
A tsunami is a Japanese term for “harbor-wave”, meaning a big wave or a series of big waves. They can be caused by a disturbance in the Ocean or other bodies of water, such as an earthquake – like what happened in Japan last March 11, 2011.
Why do building fail during a tsunami? For a building that stands in the tsunami’s path, the first wave will hit the wall facing it. The water can overload walls, windows, doors, columns, or bracing systems, and may push the building out of its foundation. A 7 feet deep wave will have pressure of 450 pounds per square feet, much more than any normal structure can withstand. The deeper the water, the higher the pressure.
Prefabricated metal buildings are perfect solutions for construction of buildings situated in seismic regions. For such structures, it is best to design them with a suspended lower floor level, even if the elevation is just modest. This creates a path for the water so it can go under the building as well as around it.
Prefabricated metal buildings should be built not at right angles with the beach. Their foundations should be deeper than usual and be braced right down to the footing.
Another design feature of prefabricated metal buildings that would make them resistant to tsunamis, is the use of a structural frame that is continuous in both directions. The frames must be designed to resist substantial seismic loads. Preferably, the lower floor must be made of concrete to give some weight. Pre-cast concrete flooring systems are available for prefabricated metal buildings.
Prefabricated metal buildings have no problems accommodating the needs of consumers in seismic regions because they can be designed to resist earthquakes and the resulting tsunamis.