Damping and frequency changes induced by increasing levels of inelastic seismic demand

Diego A. Aguirre , Luis A. Montejo

Abstract

The objective in this research is to determine the feasibility of using changes on the dynamic properties of a reinforced concrete (RC) structure to identify different levels of seismic induced damage. Damping ratio and natural frequency changes in a RC bridge column are analyzed using different signal processing techniques like Hilbert Transforms, Random Decrement and Wavelet Transforms. The data used in the analysis was recorded during a full-scale RC bridge column shake table test. The structure was subjected to ten earthquake excitations that induced different levels of inelastic demand on the column. In addition, low-intensity white noises were applied to the column in-between earthquakes. The results obtained show that the use of the damping ratio and natural frequency of vibration as damage indicators is arguable.

Key Words

damping ratio; natural frequency; reinforced concrete; bridge column; random decrement technique; wavelets; Hilbert Transform

Address

Diego A. Aguirre — Department of Civil Engineering and Surveying, University of Puerto Rico at Mayagüez, Mayagüez PR 00681-9000, Puerto Rico
Luis A. Montejo — Department of Engineering Science and Materials, University of Puerto Rico at Mayagüez Mayagüez PR 00681-9000, Puerto Rico

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