Theoretical And Experimental Study On Fatigue Performance Of Modular Expansion Joints

With the continuous development of infrastructure,the construction of urban overpasses and highway viaducts is constantly underway.The large number of modular expansion joints used in large-scale bridge construction are prone to fatigue damage due to long-term vehicle load.The damage of the expansion joint will not only seriously affect the increasing traffic volume,but also greatly improve the maintenance cost of the bridge.Therefore,it is very important to study the factors affecting the fatigue life of the modular expansion joint.Firstly,in this thesis I introduce the structural form of multi-support beam modular expansion joints,summarizes the design methods of modular expansion joints under Chinese norms and American specifications,and the differences between Chinese and American norms,and combines engineering practice with AEM320 D modular The fatigue test was carried out on the expansion joint,and the fatigue life of the expansion joint was estimated by the finite element method and the linear cumulative theory of Miner fatigue damage.At the same time,the fatigue life calculation program of multi-support beam modular expansion joint was written in Python language,and the factors affecting the fatigue life of multi-support beam modular expansion joint were studied.The research shows that(1)under the fatigue load,the strength and fatigue damage will not occur in the middle beam of the expansion joint and the support beam.(2)The stiffness of the support block and the compression bearing has a direct relationship with the dynamic response of the expansion joint structure.When the vehicle speed is large and the stiffness of the block is degraded,the dynamic response of the expansion joint structure increases,and the fatigue life of the expansion joint decreases.(3)The weld joint of the middle beam-support beam is often prone to fatigue failure.Adding reinforcing ribs at this position can make the weld section stress distribution uniform,reduce the maximum stress and improve the fatigue life of the expansion joint.(4)The horizontal fatigue load has a great influence on the maximum stress of the joint of the expansion joint without the reinforcing ribs,and the maximum stress of the joint of the expansion joint where the reinforcing ribs are provided is small.