<b>Introduction Manual for Natural Frequency Identification System of Bridge Piers by Constant Microtremor Measurement</b>

In recent years, disasters have frequently occurred due to rapid river flooding and prolonged high water levels caused by typhoons and localized heavy rainfall. It is, therefore, necessary to establish a method for monitoring the destabilization of river piers during periods of rising water. In response to this need, we have prepared an introduction manual for a natural frequency identification system, which includes an algorithm for identifying the natural frequencies of piers from microtremor measurements, the basic specifications of acceleration sensors required to construct a microtremor measurement system, the application conditions of this system, and methods for evaluating the measurement results.