The Research On Technology Of Concrete Box Girder Being Broaden With Steel Cantilever Beam

This paper puts forward a new method of widening the bridge widening method, which is steel member widening concrete box girder method. This method can solve the problem of the old bridge widening, and can ensure the reliability of the bridge. The method does not need to increase the bridge pier, does not occupy the space under the bridge, and the method is especially suitable for the widening of the bridge of the city box girder. On both sides of the original box girder set up a steel cantilever beam from a distance, the new steel cantilever beam with the original bridge through tensioning prestressed concrete box girder to form a whole. By research to the widening alteration of Suzhou industrial park cloverleaf junction, the solid model is calculated and analyzed by using the ANSYS finite element program. Main jobs of this paper are as follows:(1) First of all, we establish the ANSYS models of the scheme ? and scheme ?, and then comparing with the two projects. When the two bridge widening schemes are used in the condition of 2 and 3 load calculation, the upper edge of the contact surface of the concrete has been cracked. This can be concluded that the scheme two is better than one. we can obtained project ? is the optimization scheme.(2) Second, through adding a anchor plate in the second scheme and different prestress anchoring in different anchor plates.In the same working condition, the project ?'s the compressive stress by the transverse prestressing in the web and top and bottom plate is spread, so the maximum compressive stress of the concrete contact surface is less than project ?. So the project ? is better than the project ?.(3) Third, according to the analysis results of project ?, the compressive stress of the concrete with the steel cantilever beam floor is obviously large than that of the other locations. In view of this kind of characteristic, we set up the number of stiffening rib at the top of the cantilever beam and the bottom plate to get the project IV. We obtain the project ? whose stress reasonable an clear and the effects of optimization is obvious, so determine project ? for the final widened project.(4) Steel cantilever beam transverse prestressing tendon can't conflicts with longitudinal prestressed reinforcement, so the steel cantilever beam spacing and the position of the lateral prestressing tendon need to appropriate adjust. Through the analysis, transverse prestressing tendons of four new steel cantilever beam through upwarding 1.3 degrees in order not to conflict with longitudinal prestressed reinforcement, we optimize the project IV and get the project V. We obtain the project V whose stress reasonable an clear.(5) Then, we establish the ANSYS models of the scheme IV and the scheme V, according to the most unfavorable load case 4, the maximum stress of the new steel cantilever beam's floor, web, anchor plate and orthotropic plate are not more than Q345 steel strength design value. Therefore, it is feasible for the concrete box girder being broaden with steel cantilever beam.