Effect of the Frequency Content of Earthquake Excitation on Damage Detection in Steel Frames

Abstract

In this article, the effect of earthquake frequency content and noise effects on damage detection is inspected. For this purpose, the damage was defined as nonlinear behavior of beams and columns, and several ground motion records were scaled so that some elements yield under the applied excitation. Consequently, the acceleration response data of each floor obtained through the nonlinear dynamic analysis. Using the discrete wavelet analysis, the occurrence and time of damage in a frame can be detected based on the spikes appearing in the wavelet details plots acquired from discrete wavelet decomposition. The mean period (Tm) was utilized to compute the frequency content of earthquakes. The implications of this parameter for the analyses with dissimilar ground motion records were investigated and the results indicates that the records with low Tm are more suitable for structural damage detection. In order to examine the effect of noise or measurement errors on damage detection process, the discrete wavelet analysis was repeated with a noise introduced to the acceleration response data.

Keywords

• damage detection
• frequency content
• wavelet transform
• steel frames