Higher-Order Beam Analysis of Multiply-Connected Thin-Walled Box Beam Systems Subjected to In-Plane Loads

A one-dimensional beam analysis available for thin-walled closed beam systems (e.g., vehicle body structures), which is fast and easy to change modeling, is required to increase the initial design efficiency. However, unlike the assumptions used in the conventional beam theories, significant sectional deformations occur at a joint of thin-walled beam systems, resulting in complex and more flexible joint responses. In this paper, we propose a onedimensional beam analysis method to capture the complicated behavior of multiply-connected thin-walled box beam systems under in-plane loads, including joint flexibility. To this end, we developed a higher-order beam theory that handles the effects of sectional deformations associated with joint flexibility. In addition, we theoretically derived joint matching conditions between the kinematic variables involving sectional deformation modes. Numerical results show that the proposed method predicts joint flexibility with an average error of 10% compared to the shell analysis results.