Analysis Of The Force Impact Of Joint Length On The Hybird Beam Bridge

The new combination-concrete composite continuous girder bridge is a new structural system which adopts the structure of composite beam and the prestressed concrete beam.As the joint of two kinds of materials,the joint structure is complex,mainly including the concrete filling section and the stiffening rib transition section.The shear component in the concrete filled segment is the main transmission component.Due to the difference between steel girder and concrete beam,if the stiffness and stress transition are improper,it will affect the comfort and safety of the structure.Therefore,it is of great significance to evaluate the performance of the composite beam bridge with the smooth transition of the stiffness and stress of the joint.In this paper a three span concrete continuous girder bridge as the research object,set in the original background of bridge span across to 50 m composite beams,the rest are for the prestressed concrete beam through the joint connection,making it a new combination-mixed concrete continuous girder bridge.Using the finite element analysis software MIDAS CIVIL,the length of the transition section of 1.5m,2.0m,2.5m,3.0m and 3.5m was selected,combining with the construction of phase change of the load on the internal forces of the hybrid girder bridge,the influence of combination-mixed concrete continuous girder bridge is set up respectively finite element model analysis and calculation under the action of dead load,different impact on the overall structure of the transition section length.In addition,three kinds of connecting parts,such as PBL shear connector,shear pin connector and composite shear connector,are selected in this paper,by using ABAQUS to simulate the three kinds of joints,the stress distribution state of concrete and three kinds of joints are analyzed.Results show that when the main girder of transition section length 3.5 m,across the bending moment and joint bending moment and joint changes of the curvature is relatively good,both the steel beam and concrete beam stiffness transition is smooth,the structure more reasonable,the structure deformation and internal force transmission is smooth,the natural and the driving comfort peace is good.In addition,when the length of the transition section is increased from 1.5m to 3.5m,the maximum tensile stress of concrete is gradually reduced,and the decreasing trend is gradually reduced,at the same time,there is a certain degree of reduction in the force of the bottom plate connecting pieces under the action of the shear force.Among them,the reduction of the force on the webs of the web is 20~25%,and the reduction of the force on the bottom plate joints is about 15-20%,but this slowdown is not an unrestricted increase.However,as the length of the transition period increases,the mitigation effect gradually decreases,the longitudinal stress distribution of the stiffening rib is not related to the length of the transition section,and the longitudinal stress of the stiffener is basically completed within 0.6m of the pressure plate.