Study On Shear Lag Of Main Beam Of Long Span Steel Concrete Composite Beam Cable-stayed Bridge

Because of its light weight and high rigidity,the large-span steel-concrete composite beam cable-stayed bridge is competitive in the construction of modern bridges.It is characterized by the connection between the bridge deck and the steel main beam through shearing bonds and the common force.However,the shear lag effect of the laminated beam under load is very obvious.If the unevenness of the distribution of the normal stress of the bridge deck in the width direction is not considered,the local stress of the bridge deck may be excessively damaged.Therefore,relying on the second bridge of Poyang Lake as the engineering background,this paper comprehensively applies the shear lag effect of "duplex steel" type composite beams to the "duplex steel" type composite beams through theoretical derivation and numerical simulation.Research.The main work content has the following aspects:(1)Based on the principle of energy variation,the piecewise function curve is used to formulate the distribution of the longitudinal displacement of the wing along the lateral direction,and the governing differential equation and its closed solution of the shear lag effect of the "double-beam" composite beam are derived.(2)Using the method of regression analysis,an energy variation method for simulating the longitudinal displacement of the wing with a function containing unknown parameters is proposed for the "double-worked steel" type composite beam.According to the principle of minimum potential energy,the parameters of the normal stress are derived,the corresponding finite element model is established,and the unknown parameters in the stress equation are programmed by the MATLAB program to obtain the regression equation.The theoretical solution and the numerical solution are compared and analyzed by example calculation.The results show that the analytical solution under the regression equation is more consistent with the solution obtained by the finite element method,and the error is in the acceptable range.It is verified that the regression analysis method is used to formulate the longitudinal warping displacement.The correctness and applicability of the function.(3)Based on the second bridge of Poyang Lake,the full-bridge finite element model and the local finite element model were established by using MidasCivil and ANSYS finite element software respectively.Aiming at the cross-section form of "double-worked steel" type composite beam,the influence of the interception length ofthe local model on the calculation accuracy is studied,which provides reference value for the research of shear lag effect of the main beam of the same type cable-stayed bridge.(4)By establishing the finite element model,the normal stress of multiple sections of the cable-stayed bridge with large span steel-concrete composite beams is calculated and analyzed,and the shear lag effect of the bridge deck at different positions along the span of the bridge is studied,and the rigid domain is established.The anchoring form of the cable stayed on the main beam is studied,and the normal stress distribution of the deck in the length of the anchor plate on the main beam is studied.(5)The shear lag effect of steel-concrete composite beam considering longitudinal slip effect and overall ascending(lowering)temperature is analyzed by numerical simulation.The influence of bridge deck transverse slope setting on normal stress distribution of composite beam main beam section is studied.