Pancake Collapse

Another common problem that occurs in an earthquake is the pancake collapse. This is often caused by the failure primarily of only one or two floors. This may lead to the kind of appearance shown in the two examples to the left. Both these are taken from cities in the eastern countries were pancake collapses are common. One of the main causes of the high frequency could be simply that there are a lot of high rise buildings in the eastern countries. However, the USA also has many high rise buildings and they do not seem to fail. What could be the possible reasons for these irregularity? 

In many cases the remainder of the building may maintain it's integrity, but it will need to be demolished in due course. If the failure occurs on more floors than shown above the whole side of the building may fail. The image shown on the right shows two examples. Clearly the issue with a pancake collapse is with the vertical/horizontal support structures. This is clearly an issue that has been addressed to a higher standard in the USA than in eastern countries. The first step to avoid these problems is to strengthen the upright supports and the vertical joints. Metal girders are a good start and more complex technology is being created all the time to help remove the problems and minimise the risk to life.

The best way of ensuring that buildings are able to withstand earthquake forces is to enforce building standards. The final page will take a brief look at building standards and the problems that are often encountered with the enforcement of such regulation.

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By Paul Wittle