Research On Analysis Method Of Main Beam Of Composite Girder Cable-stayed Bridge

The modern composite girder cable-stayed bridge adopts the steel double main beam,and the precast bridge deck and the steel beam lattice form a cable-stayed bridge with the same force by the shear-welded nail through the cast-in-place joint concrete.Compared with concrete beams,it has the advantages of large spanning capacity and components can be made in the factory.Compared with steel main beams,it has the advantages of more steel,wind resistance and higher structural rigidity.In this paper,the composite girder cable-stayed bridge,the Chibi Yangtze River Bridge,is used as the engineering background.The finite element tools such as Midas and ANSYS are used to establish the analysis model from the member to the segment,from the segment to the whole bridge,and the main beam of the composite girder bridge is revealed.The spatial force mechanism provides the optimal design and simplified calculation method for the main girder of the composite girder cable-stayed bridge.Specifically,the work of this paper is as follows:(1)Carry out finite element simulation on the standard launch test in European Standard 4,study the mechanism of the introduction of shear nails,compare the finite element results with the calculation results of shear strength and shear stiffness of shear nails in China’s specifications.The difference is to explore the applicability and limitations of shear springs with shear springs.(2)The finite element model is established by using the shear stiffness of shearing nails to analyze the main beam section of the cable-stayed bridge in this example.Under the effect of temperature difference and double cable,the bridge deck stress results of the two are compared when using the fine solid model and the simplified plate-shell model to simulate the bridge deck.Establish a design method for the main beam joints based on the energy principle.(3)The whole bridge model is built by the shell-and-shell unit to study the spatial force of the bridge deck under the dead load of the bridge,and the variation of the effective width coefficient of the main bridge longitudinal bridge is studied.An effective width coefficient prediction method based on the axial stress of the bridge deck is established.The research results are as follows:(1)In the simulation of the launching process,the spring element is used to replace the shearing nail entity,and the obtained shearing force and displacement result are close to each other,and the difference is less than 25%.(2)In the bridge,the strain beam method is used to design the composite beam joints so that the total strain energy of the combined structure does not exceed 105% of its "ideal minimum" and the strain energy of the joint does not exceed 3% of the total strain energy.,think that the connector design meets the requirements.(3)Using the simplified plate-shell model instead of the fine solid model,the calculated bridge deck stress results are close,and the correlation coefficient is above 0.7.(4)Except for the mid-span,auxiliary pier and side piers,the effective width coefficient of the deck is above 0.7;the effective width coefficient of the bridge deck in the mid-span area fluctuates between 0.3 and 0.7;effective at the auxiliary pier and the side pier The width factor is reduced to 0.55 and 0.1,respectively.(5)The effective width coefficient prediction method based on the axial stress of the bridge deck can estimate the effective width coefficient range of the composite beam cable-stayed bridge deck when only the beam model is established,which is less than 0.05 from the accurate result of the shell model.