Theoretical and experimental study of coupled vibrations of channel beams

Abstract Studies of the free vibrational behavior of channel beams, which are partly constrained along one end or one flange, are of prime importance for structural engineers. In this paper, studies of thin-walled channel beams with different cross-sectional areas and lengths were conducted using theoretical and experimental approaches. The theoretical approach was based on analytical and finite element methods. The experimental approach utilized the methods of laser hologram interferometry. In the studies reported herein, emphasis was placed on dependence of the natural frequencies and the mode shapes on the cross-sectional area, and on determination of the prediction capability of the Timoshenko model considered in the analytical analysis. The results show that lower modes of slender channel beams are characterized by global beam motions and a non-deforming cross-section. More pronounced C-shapes are increasingly influenced by plate deformations in the web and flanges. The Timoshenko theory compares well with experimental data on natural frequencies, but only for slender beams. The results of the finite element analysis generally compare well with experimental data.