Variation of vibration properties of six RC slabs at different damage levels

Abstract

Structural damage will cause changes in structural vibration properties such as vibration frequency, mode shape and damping ratio. Therefore the structural vibration properties are commonly used in structural condition monitoring and damage identification by comparing them with the theoretical or numerical vibration properties of the undamaged structures. In practice, owing to variations in workmanship, material properties, and environmental conditions, the structural vibration properties derived from theoretical or numerical model may differ from the actual values. This may lead to the damage being undetectable if the change in vibration properties owing to Structural damage is smaller than the modelling difference. In this study, six continuously supported RC slabs having the same dimensions and support conditions were constructed in the laboratory. Four slabs were tested to failure after the concrete was cured 35 days, and another two left unloaded in the lab for more than a year before load tested to failure. Vibration tests were performed on all the slabs before and during the tests at different loading levels to extract slab vibration frequency, mode shape and damping ratio. The primary objective of the study is to demonstrate and quantify the variations of the vibration properties of the RC slab structures.