Calculation method for bending-warping shear stress of single-box multicell box girders

Abstract

To investigate the influence of the shear lag effect on the bending shear stress of single-box multicell box girders (MCBG), the shear lag warping additional deflection is selected as the generalized displacement. The governing differential equations and boundary conditions for the shear lag of the MCBG are derived using the energy variational method. Based on the shear lag warping deformation state of the MCBG and by employing the microelement equilibrium differential equation and the coordination conditions for shear lag warping deformation, the calculation method for the bending-warping shear stress of the MCBG is derived, and the influence of the width-to-span and height-to-span ratios on bending-warping shear stress is analyzed. Example analysis shows that the bending-warping shear stress of the MCBG calculated by the proposed calculation method coincides with the finite element solution, and the warping shear stress satisfies the self-balancing condition of shear warping, thus verifying the accuracy of the proposed method. The warping shear stress exhibits an antisymmetric distribution about the vertical axis of symmetry and has a weakening effect on the shear stress of the elementary beam (EB). The larger the width-to-span ratio is, the larger the proportion of the warping shear stress of the EB. The larger the height-to-span ratio is, the smaller the proportion of the warping shear stress and the more significant the influence of the width-to-span ratio. The more the number of cells is, the smaller the influence of the warping shear stress on the total bending shear stress. The influence of the shear lag effect can be ignored in the calculation of the bending shear stress of three or more cells in the MCBG.

Keywords

single-box multicell box girders (MCBG) / shear lag / shear warping coordination conditions / shear stress / parametric analysis

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Funding

The National Natural Science Foundation of China(52368020)

Gansu Provincial Universities Young Doctor Support Project(2024QB-047)

Gansu Province postdoctoral Fund(386824)