Premature failure of expansion joints is a concern for bridge owners. After opening to traffic, the Jiangyin suspension bridge experienced frequent damage in expansion joints, and the problem remained unsolved even after replacement with new expansion joints and installation of viscous dampers at the girder end. This paper aims to clarify the failure mechanism of the expansion joints based on field test results. The field tests consist of three scenarios: static test, influence line test, and truck pass-by test. The tests aimed to investigate the behavior of expansion joints on both global and local scales. In the static and the influence line tests, it was found that strain response of the expansion joint is affected by the girder deformation, which reflects effect of global behavior of the bridge on the expansion joints. The truck pass-by test result shows that direct impact of heavy truck axles could induce high strain in expansion joints, which indicates that the expansion joints are affected by vehicle axle loading on a local scale. These results are in accordance with the premature failures observed in the expansion joints of the Jiangyin Bridge. (C) 2016 American Society of Civil Engineers.