Optinal Research On Joint Position Of Combination-Concrete Mixed Continuous Beam Bridge

Combination-concrete continuous mixed beam bridge means to use composite beams and concrete beam of combination form on continuous beam bridge.Specific as follows: some of the main span uses composite beam,and the side span uses concrete beam,than uses different types of connectors to connect them into a whole bridge.The weight of the combination-concrete continuous mixed beam bridge is reduced when comparing with concrete beams,therefore it reduces the force of the structurethe.Because of the advantages already mentioned before,the new bridge can improve the span's capacity of the bridge and to a certain extent reduce the size of structural members.Integral hoisting method can be adopted for the main span of the combined beam to reduce the impact of traffic under the bridge during the progress of construction.In addition,as a result of the combination of beams using concrete concrete slab,it improves the stability of the steel beam,also makes the bridge deck can be used asphalt and concrete pavement so the fatigue problem of steel beam is weakened,so as to improve the durability of the pavement layer.The joint position directly affects the length of the composite section and the internal force of the main beam,and the joint position is the weak position of the whole beam,therefore,it is necessary to optimize the position of the joint.In this paper,a prestressed continuous beam bridge with three spans in Changchun is used as the background of the research.Under the condition of keeping the original shape of the bridge and the span of the original bridge,part of theconcrete beam of the original bridge's main span longing for one hundred and fifty meters change to steel-concrete combined beam structures,making the original bridge become a new bridge which is combination-concrete continuous mixed beam bridge.This paper uses Midas civil ' s finite element to simulate the main girder,than calculates the main beam with different joint positions.Under the action of dead load and considering the influence of the process of construction on the internal force,the author summarizes the effects of the change of the joint position on middle bending moment,moment at the support,moment of joint,joint shearing force and the strain energy of moment in the span of the main beam.Aiming at the problem of joint position,this paper uses the methods of mathematical programming to build the multiobjective and optimal model in the targets of joint moment and joint shearing force to be the minimum.A linear weighted method based on a single objective problem is used to solve the problem,consequently reach the optimal location of joints under certain constraint conditions.Finally,the paper references to the choice of the joint position in the design of the combination-concrete continuous mixed beam bridge.