Condition assessment of elastic bearing supports using vibration data

Health monitoring of engineering structures has gained a lot of interest over the last few years. Many engineering structures suffer damage and deterioration when exposed to various loading and environmental changes during their lifetime. This seriously affects structural performance and may even lead to catastrophic structural failures. Thus, inspection and testing of structural components for deterioration and damage is essential when deciding on the maintenance and repair strategies for at-risk structures. A current alternative approach to conventional structural testing methods is dynamic testing, which acquires modal parameters and relates these to the health status of a structure. The fundamental idea underlying the dynamic approach is that modal parameters, namely natural frequency, mode shape, and modal damping, are functions of physical properties of the structure, such as mass, damping, stiffness and the support conditions. Therefore, any change in the physical properties or support conditions causes detectable changes in the modal parameters. Elastic bearing pads are widely used for supporting bridge girders, and as base isolation of tall buildings to reduce seismic demand. The bearings are exposed to various loading conditions and environmental changes which cause deterioration of its stiffness with time. Monitoring of changes in elastic bearing stiffness is very important in ensuring timely maintenance or replacement to prevent occurrence of any serious damage to the structure.