Numerical Solution Of Shear-lag Effect In Composite Girder Cable-stayed Bridge

The steel-concrete composite girder cable-stayed bridge has more and more applications in practical engineering because of its wide width,light weight,excellent seismic performance and ease of construction.However,due to its large horizontal scale,shear-lag effect is obvious,especially as cable-stayed bridge,which has a significant concentrated axial force acting on its girder,the shear-lag effect can not be ignored,otherwise it will endanger the safety in construction process.In previous research,many scholars have carried out a lot of theoretical analysis,numerical simulation and experimental research about the subject of shear-lag effect in compression-bending girder,and achieved fruitful results,make great contribution to the development of ?-shaped girder cable-stayed bridge.However,the studies on shear-lag effect of the thin-walled compression-bending members often ignore the interaction between axial displacement and shear-lag effect,simply including the load potential energy of beam-column effect in the energy variation method,to consider the influence of axial force;or applying complex multi-parameter corrections to shear-lag warping displacement,to account for the effects of additional axial forces.However,these studies do not regard the axial displacement as an independent degree of freedom in the analysis of shear-lag effect.The axial displacement is neglected in the stiffness matrix of beam element only considering the mutual influence of deflection and shear-lag effect,which can not form a uniform method for the analysis of shear-lag effect of thin-walled compression-bending members,and can not be well applied to the shear-lag analysis in cable-stayed bridge.Based on the existing theories,the paper derived the governing differential equations considering the coupling of axial displacement,bending and shear-lag with its corresponding boundary conditions by introducing the section axial displacement,and discussed the interaction between axial displacement and shear-lag effect.Based on the governing differential equations considering the coupling of axial displacement,bending and shear lag,the paper established the finite segment method,and derived the element stiffness matrix of finite segment considering shear-lag effect.Combined with displacement interpolation technique,a bidirectional interpolation beam element is proposed to effectively solve the artificial assumption of shear-lag warping displacement.Based on the rich libraries,the one-dimension finite element program for shear-lag analysis of thin-walled compression-bending members is constructed by using the dynamic programming language Python,to verify the accuracy of the proposed element stiffness matrix.Finally,based on the bridge construction monitoring simulation software CSB,the shear-lag effect in the construction process of Hekou ?-shaped composite girder cable-stayed bridge is analyzed.After numerical simulation and experiments,it shows that the proposed method is accurate and practical,can be widely used in the open and closed thin-walled compression-bending members with various cross-section forms,and provides a reliable method for analysis of shear-lag effect in practical project.