DIAGNOSIS OF BRIDGE BEARINGS BASED ON FIELD MEASUREMENTS

A bridge bearing is the structural member to be installed in the connecting portion between superstructure and substructure. The purpose of the bearing is to transfer load from superstructure to substructure, to allow necessary rotation and expansion of superstructure by live load and temperature variations and to absorb relative motion of superstructure and substructure. Bridge design is based on whole bridge analysis model, which the bearing functions are reflected. When the bearing functions deteriorate, it is possible for structural system of the bridge to be changed and have an effect on functions of superstructure and substructure. Thus, it is important to maintain functions of bearing as structural member. However, it is difficult to evaluate the degree of deterioration of the bearing function in the visual inspection only. Considering these points, we studied qualitative evaluation method of basic functions (load supporting, horizontal moving and rotation) for bridge bearing as structural member based on measuring displacement and strain. In this study, measurement of displacement and strain on the bearing of the steel bridge in service was conducted, and evaluation of deterioration degree of bearing was attempted with evaluation method proposed.