Composite box girder beam element with corrugated steel webs considering shear force interaction in flange plates

To investigate the shear force distribution in composite box girder with corrugated steel webs (CSWs), a novel box girder beam element (TBTF-CSW) comprehensively was proposed considering the shear force distribution relationship between CSWs and flange plates, as well as the influence of diaphragm constraints. By introducing shear strain transfer coefficients for the flange plates, the shear forces carried by CSWs, top and bottom flange plates were effectively decoupled. Considering the variable cross-section effect, analytical expressions for the shear force distribution in variable cross-section composite box girders with CSWs were derived, and a theoretical analysis model was established considering shear deformation influence in both the flange plates and CSWs. Based on the energy variational principle, the controlled differential equations that consider the shear force interaction of the flange plates were formulated. The shear deformation of the CSWs was then introduced as an additional degree of freedom. The homogeneous solutions of the controlled differential equations were used to construct interpolating functions for the generalized displacements, including vertical deflection, CSWs equivalent shear strain, and equivalent bending rotation. By integrating the finite element method, a two-node six-degree-of-freedom box-girder beam element considering the shear deformation influence of both CSWs and flange plates was developed. A series of typical numerical examples were analyzed to verify the accuracy and applicability of the TBTF-CSW beam element in calculating the shear stress and shear force distribution for composite box girders with constant and variable cross-sections. The results indicate that in the constant cross-section composite box girders with CSWs, the CSWs carry the majority of the shear force, with the distribution primarily affected by material characteristics and geometric parameters. The diaphragms and concentrated loads introduce local disturbances. In variable cross-section composite box girders, the axial force in the bottom flange plate leads to significant variable cross-section effect. Either the bottom flange plate or CSWs may experience "shear overdistribution". In such cases, it becomes unsafe to assume that the CSWs carry the entire shear force. The proposed TBTF-CSW beam element provides an effective support for theoretical analysis of shear force distribution and engineering design for composite box girders with CSWs.