Research On The Loading Lateral Distribution Of Prestressed Concrete Small Box Girder Bridge

The small box beam section has many advantages such as large bending stiffness,torsional stiffness,high economy and fast construction speed.It has been rapidly developed and widely used in medium and small span bridges at home and abroad.In the bridge design,stress analysis and calculation,the calculation of the loading lateral distribution coefficient is an indispensable component.Therefore,the analysis and discussion of the loading lateral distribution law of this type of bridge,and the loading lateral distribution practical calculation method to adapt to this type of bridge have important research significance for optimization and improving the design level of the current prestressed concrete small box girder bridge.In this paper,taking a prestressed concrete small box girder bridge with a standard span of 20m as the engineering background.According to the structural characteristics of the small box girder,the lateral distribution of loading is analyzed by means of spatial finite element numerical simulation and model test to discuss the loading lateral distribution law of stress concrete small box girder bridge and the applicability and accuracy of its theoretical calculation method.The specific research work is as follows:(1)Space finite element numerical simulation:spatial finite element software is used to establish superstructure solid element calculation model of the prestressed concrete small box girder bridge.By extracting the deflection and stress value of the small box girder bridge model under different loading conditions,the deflection distribution curve and stress distribution curve are obtained.To discuss the accuracy and reliability of inverse loading lateral distribution coefficient of the deflection effect and stress effect,the inverse loading lateral distribution coefficient based on the deflection and the stress effect is compared with the calculation results of the rigid beam method.(2)Model test research:According to the prototype of 20m standard span small box girder bridge with prestressed concrete,the model of which was manufactured with 10:1 ratio,and inserted pre-stressed steel strands into the reserved holes of the web and bottom plate of the small box beam model.The static loading test is carried out on the bridge model according to the control loading and loading conditions in the test plan.And the measured results were analyzed and compared to investigated the loading lateral distribution law of the prestressed concrete small box girder bridge.(3)Research on practical calculation method of lateral loading distribution:adopting the rigid beam(plate)method and the hinged plate(beam)method in the traditional loading lateral distribution calculation method to calculate the coefficient of lateral distribution of the above 20m span prestressed concrete small box beam bridge loading at mid-span.By comparing the calculation results of the hinged plate method,rigid beam method,spatial finite element numerical simulation method and model test method,it is found that the loading lateral distribution coefficient of the prestressed concrete small box girder bridge calculated by the hinged plate method is closer to the loading lateral distribution coefficient calculated inversely by the deflection effect of the space finite element and the model test method.(4)Based on the above research,this paper put forward a corrected method suitable for the calculation of loading lateral distribution of small and medium-span prestressed concrete small box girder bridges,which combines the calculation results of the traditional rigid beam method and the hinge plate method,and is closer to the actual value.