Fiber beam element for thin-walled steel members considering shear deformation based on co-rotational coordinate system

To perform a static elastic-plastic analysis of complicated thin-walled box section steel structures with highly computational efficiency, a co-rotational coordinate system-based fiber beam element considering shear deformation for thin-walled steel members is proposed. Aiming at the intermediate-length members, the element stiffness matrix is derived based on the Euler beam theory. Thin-walled elements are adopted to simulate the thin-walled section, which can provide section fiber information for the consideration of material nonlinearity. And the section method can be adopted to calculate the shear deformation coefficients to consider the effect of shear deformation. In the solving process, rigid body displacements are eliminated by the co-rotational coordinate system method to expedite convergence. Meanwhile, a numerical adjustment strategy for material nonlinearity is presented, which can enhance the applicability of uniaxial constitutive model when it is applied to the beam element considering shear deformation. And corresponding calculation code is written. The analysis of curve beam, flat arch, cantilever beam and column verifies the accuracy of the developed program in handling geometric and material nonlinearity calculations of thin-walled components. Furthermore, calculations of frames with stiffened section steel members indicate that the developed program can effectively predict the nonlinear response of structures with complex thin-walled sections considering shear deformation. © 2024 Science Press. All rights reserved.