To estimate the fatigue life of long-span steel bridge more accurately, this paper proposes a method for
estimating the fatigue life of long-span bridges by considering vehicle-bridge coupled vibration. Firstly, the universal
equation of vehicle-bridge vibration is derived based on triaxial standard multi-scale model of fatigue vehicle and bridge,
and relevant program for vehicle-bridge coupled vibration is programmed. Secondly, a method for estimating the fatigue
life of long-span steel bridge is proposed based on fracture mechanics theories, and the analysis process is expounded in
details. Finally, the method for estimating fatigue life proposed in this paper is verified by taking a double pylon cablestayed
bridge with orthotropic steel bridge deck slab as an example.