Experimental Evaluation of Seismic Residual Performance for Deteriorated Rubber Bearings in Highway Bridges

Abstract

Aging deterioration of rubber bearings (elastomeric bearings) in highway bridges is an issue of great significance for bridge management, in view of the influence to the seismic performance and functionality during regular condition of the bridges. In Japan, the use of rubber bearings in the construction of bridges started in early 1980’s, and also an extensive number of conventional bearings of existing bridges have been extensively replaced with rubber bearings since 1995. As a consequence of the duration of service exceeding 20 years, a considerable number of surface rubber cracks of rubber bearings due to aging deterioration have been found by inspection of highway bridges. In this study, seismic residual performance of rubber bearing samples with aging deterioration taken from a highway bridge site was evaluated by shear loading tests and the material tests. The reduction of the load bearing capacity and that of the stiffness obtained by the test are indicative measures of the aging deterioration effect on the rubber bearings. A particular feature of debonding between rubber and steel layers are found in the deteriorated bearings.