Analysis Of Crack Growth In Seamless Birdge Expansion Joint Based On Extended Finite Element Model

As a new kind of bridge expansion devices which has been gradually applied in recent years,the seamless bridge expansion joint is easy to be damaged because it is directly subjected to repeated actions of the vehicle loads,changes in temperature and so on.Cracking is the most common form of damage.If cracks begin to appear in the seamless bridge expansion joint,it will not only destroy the continuity and integrity of the bridge expansion joint structure,but also affect the safety and reduce the service life of the seamless birdge expansion joint.The existing researches on the cracks of the seamless bridge expansion joint are still in the preliminary stage and lack the in-depth analysis of the crack growth in the seamless bridge expansion joint.In order to solve the problem,the three-dimensional model of bridge seamless expansion joint was established based on the extended finite element method to achieve the propagation of the cracks in the seamless bridge expansion joint.In this paper,the main research works are as following:Firstly,combined with the theory of transient temperature field,study on the crack propagation of the seamless bridge expansion is affected by the temperature because of the difference of initial temperature,cooling amplitude,cooling rate,temperature shrinkage coefficient of the bridge expansion joint and initial crack position.The cracking law of the seamless bridge expansion joint under the change of temperature was summarized by obtaining the crack parameters such as stress intensity factor,the path of crack growth and the relationship between time and the volume value of crack growth.Secondly,the dynamic load of the wheel was applied on the surface of the seamless expansion joint in order to accurately reflect the effect of wheel load on the seamless birdge expansion joint.The influence of different loads on the crack expansion of seamless expansion joint of bridge was studied by changing the position of load,the size of vehicle load,the speed of vehicle,the elastic modulus of elastomer and the driving state.Combined with the CZM,the cohesive element is added to the interface layer of the seamless bridge expansion joint to simulate the influence of load on the interface layer under different interface states.Finally,the thermal-mechanical coupling model was established to explore the influence of temperature and load coupling on the seamless bridge expansion joint due to the change of crack length and angle,and compared with the effect of temperature and load alone.The actual cracking situation of seamless expansion joint of bridge was simulated at high temperature in summer and low temperature in winter with the temperature field in practical engineering.The causes of crack growth in the seamless bridge expansion joint in extreme weather were analyzed from temperature field,temperature stress,crack propagation path and volume change.The research results of this paper provide a theoretical basis for the choice of suitable environmental conditions and daily maintenance measures for the seamless bridge expansion joint.