Earthquakes are one of the most (indirectly) destructive forces of nature. It’s an erroneous assumption to think that earthquakes destroy the built environment because it’s buildings and infrastructures themselves that are destructive. Inadequate accountability for seismic loadings is usually the culprit in a structural collapse during an earthquake tremor. Therefore, various countries have devised specific and stringent structural designs to take into account large seismic loadings. For example, this video shows just how effective a Japanese floor isolation design during the powerful 2011 Japan earthquake.
The engineers of the structure have intelligently designed the floor as an isolated system so it wouldn’t crack and initiate collapse during an earthquake. They have captured the essence of seismic design by devising the floor to detach from the building’s wall and not displace along with the structure.
Large displacements occur because all structures are stiff, so when a continuous dynamic force is applied, they bend and flex producing large strains. And these displacements always begin from the weakest part of a structure – the connections. Cracks and damages would then propagate along the structure from the connections creating significant fault lines that result into failure or collapse. Many seismic concepts are used in engineering design like damping but this clever floor isolation system may be more suitable for structures like buildings.
By detaching from the building’s wall, the isolated floor remained stationary during the tremor. The camera was fixed on the building’s wall giving off the illusion that the floor was moving. This incredible seismic floor isolation design both saved the building and the people’s lives.