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.

桥梁支座（bridge bearing）是设置于上部结构与下部结构连接部位的结构构件。其作用在于将荷载从上部结构传递至下部结构，适配活荷载与温度变化引发的上部结构必要转动及伸缩变形，并吸收上下部结构间的相对位移。桥梁设计依托反映支座功能的全桥分析模型（whole bridge analysis model）开展。当支座功能劣化时，桥梁结构体系可能发生改变，进而影响上部与下部结构的工作性能。因此，保障支座作为结构构件的功能完好至关重要。然而，仅通过目视检查（visual inspection）难以评估支座功能的劣化程度。针对上述情形，本研究基于位移（displacement）与应变（strain）测量，针对作为结构构件的桥梁支座的三项基本功能——承荷、水平位移及转动，开展了定性评估方法的研究。本研究对在役钢桥支座的位移与应变进行了现场实测，并基于所提出的评估方法尝试对支座的劣化程度进行评定。