Determination of Structural Dynamic Characteristic Using GPS Device

Structural dynamic parameters: natural period, shape modes and damping ratio of vibration, play a decisive role on the seismic behavior of those structures. There are several methods for determining of the structural dynamic parameters, such as: free vibration, ambient vibration and force vibration tests. In this research the structural response of a three-story building (the natural frequencies of vibration and the structural damping values) are monitored by a two-frequency GPS device mounted on the structure. The time in full oscillation of the structure will be the natural period of vibration. The damping ratio is determined using logarithmic formulation. The results from analytical method are the same as the experimental results approximately. For example, the natural period in X direction was determined 1.07 and 0.93 Hz using GPS and analytical methods. Comparing the results of the experiments and the results of the computer analysis shows the good accuracy in determining the parameters.