Estimation Technique of Damping ratio Using the Integral of Response Power Spectral Density Function

The wind-induced vibration of structure is very sensitive to the damping ratio of governing modes of interests. Research to identify the damping ratio from the structural response have been developed for several decades, however is still challenging. A novel estimation technique of damping ratio of a structure is proposed in this research, which is based on the integration of power spectral density (PSD) function. The damping ratio estimation concept is devised on the principle that the integration of PSD have a flattening effect of the external load spectral density so that the integral of spectral density function of decomposed mode can be very closed to the corresponding theoretical integral function. The damping ratio can be identified by comparing the two integral functions. In order to extract the damping ratio, the properties of the integral of theoretical spectral density function is examined, and it is also shown that the estimation technique is applicable to the modal response separated from a non-classically damped system. For the validation of the developed technique in this study, numerical analysis for the mathematical model and application for the site-situ measurement were carried out. From the verification process, it was shown that the technique to estimate the damping ratio is robust and reliable with high stability