Study On The Collision Effect Of Simply-supported Skew Girder Bridge Under Earthquake

Under earthquake,the upper structure of the longitudinal and transverse displacement in the the skew girder bridge will be too large,if the collision happens in the upper structure,and ultimately lead to the destruction of the bridge or even falling beam.At present,the research on the seismic behavior of the skew girder bridge is mainly based on numerical analysis and theoretical analysis,and the experimental research on the skew girder bridge is mainly focused on the static or collision-free response.Therefore,it is of great necessity to carry out seismic simulation shaking table test on the skew girder bridge.The collision process of the skew girder bridge under earthquake is simulated by the shaking tablet test.The results of shaking table test and finite element software simulation are compared and analyzed to provide reference for the accuracy of collision simulation in finite element software.In this paper,under the prerequisite of statistical analysis of structural design parameters,a single-span structure with skew angle of 45 ° is selected as the research object.The shaking table test and the numerical simulation about the collision of the single-span simply supported skew beam bridge are carried out.The main work and conclusions are as follows:(1)A shaking table test model was designed and manufactured.Through the shaking table test of the scale model,the effect of the peak acceleration of the earthquake on the seismic response of the single-span simply supported beam bridge is analyzed and the results of the numerical analysis and test under the collision and non-collision are analyzed.To investigate the impact on the upper part of structure.The acceleration and displacement of the bridge deck increase with the increase of the peak value of the input ground motion,and the number of collisions of the structure increases,and the acceleration response at the acute angle of the collision surface increases obviously.Compared with the results without collision,the collision can not only increase the acceleration and the lateral displacement of the srtucture,but also make the longitudinal displacement be controledl.(2)The finite element model of different collision simulation method is established and the numerical analysis and experimental results under collision are compared with each other to discuss the reasonableness of the collision simulation of the skew girder bridge and finally to provide the reference for the accuracy of collision simulation in the finite element software.By comparing the experimental data with the numerical simulation,the numerical simulation results are close to the experimental values when the stiffness of the axial girder is 0.1-0.5 times more than siffenss of the collision.Considering the calculation error of each model under different input peak and the stability of the results of different models under variable stiffness,the conclusions are drawn:The Hertz-damp model has wide adaptability and high accuracy.When the stiffness of the Hertz-damp model is 0.5 times the stiffness of the axial girder,it can meet the actual requirements.(3)Considering the collision between different materials in practical engineering,this paper has carried out shaking table test and numerical simulation research on the collision effect of steel-concrete and rubber-concrete on the basis of the above research.The Hertz-damp model is better than the linear elastic model and the Kelvin model in terms of the collision response of different material structures.It is worth noting that,for steel-concrete collision,the collision stiffness is about 0.5 times the axial stiffness of the main girder;and for the rubber-concrete collision,the parameter is recommended to take 0.1 times the axial stiffness.In addition,through the comparative analysis of the collision reaction between different materials,it is concluded that the collision reaction can be effectively reduced when the filling material in the gap of the expansion joint is made of flexible material(for example,rubber).The use of a flexible material in the gap not only reduces the impact force,but also does not increase the displacement response the other side of collision surface.