Abstract: Expansion joints are key bridge components and play an important role in ensuring bridge load-carrying capacity and service safety.Vehicle-induced impact on the bridge deck is a major cause of damage and failure in expansion joints.A field vehicle-induced vibration test was conducted on the modular expansion joint of a newly constructed bridge.Measured data on the impact vibration acceleration and dynamic strain of the load-bearing components under different vehicle loading conditions were obtained.The vibration response characteristics and evolution patterns of the expansion joint were analyzed with respect to varying vehicle speeds,vehicle loads,travelling directions,and front and rear axle loads.The results show that the dynamic response of the expansion joint increases significantly with vehicle load.The acceleration response first increases and then decreases as vehicle speed increases,whereas the strain response decreases with increasing vehicle speed.The acceleration response under uphill traffic loading is greater than that under downhill traffic loading.The field vehicle vibration test can provide important engineering measurements and technical support for mechanical mechanism analysis,service condition assessment,and operation and maintenance management of bridge modular expansion joints.