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Contributions from Earthquake Engineering

Minimizing damage to the built environment

The focus of the earthquake engineering community is largely directed towards minimizing damage to the built environment during an earthquake. The objectives of current research typically involve the improvement of building codes, the retrofitting and monitoring of public infrastructure, evaluating methods for hardening lifelines, or risk assessment for specific industrial processes.

The red wire loop

A simple but very effective sensor—at least for emergency response—is the "red wire loop," a wire or optical fiber that senses fractures and strain in structural elements.

Acceleration sensors

Simple acceleration sensors can also be used to monitor whether a civil structure has been subjected to forces generating stress beyond its design limits— which eventually would result in permanent structural damage. These methods are generally a form of modal analysis.

Even simple tilt sensors can reflect whether key structural elements have suddenly undergone permanent deformation. Even a small amount of permanent tilt is a sure indicator of a serious structural failure.

On the high end of complexity, a larger building can be equipped with dozens of acceleration sensors, forming a complex multichannel data acquisition system. Commonly connected to a powerful UNIX workstation equipped with appropriate software, this instrumentation reveals a set of vibration parameters characteristic of the actual condition of the structure, for example, modal frequencies, mode shapes, and modal damping.

Straser and Kiremidjian (1998) propose combining post-earthquake modal information with previous records in a Bayesian framework, thus providing actual estimates of probable damage locations and severity.

No matter which technology is used for damage detection, a valuable contribution to emergency management can be made if status information about the most important civil structures and lifelines is conveyed to the crisis center in as close to real time as possible.

Further information about institutions of earthquake engineering will soon be available on our list of websites related to earthquakes.