Vibration analysis of piecewise straight thin-walled box beams without using artificial joint springs

This investigation presents a vibration analysis of a thin-walled box beam system having angled joints by employing a higher-order beam theory that incorporates warping and distortional degrees of freedom (dof) in addition to the standard Timoshenko dof. In the proposed approach, no artificial spring is inserted between beams connected at an angled joint, but a systematic technique to match all dof of the connected beams is employed. There were similar efforts for static problems, but the vibration analysis using a higher-order beam theory without using joint springs is carried out here for the first time. Three cases were investigated: two box beams connected at an angled joint, a curved box beam modeled by several straight box beams each of which meets an adjacent beam at an angled joint, and a box beam forming a closed loop. The predicted vibration results by the developed approach were compared with shell analysis results.