The Inclusion of Warping in Free Vibration of Structures

Thin walled cellular structures are widely used in many civil, mechanical and aerospace engineering applications. These applications have increased with the economic necessity of providing high strength with low weight and cost. Structural analysis of thin walled girder is usually performed by the beam theory. In the present study, the effect of cross-sectional warping on the dynamic behavior of box girder deck is investigated using discrete element approach in idealizing the structure and incorporating the warping as a seventh degree of freedom in a space frame element. Shear deformation due to uniform torsion in addition to transverse shear deformation are taken into account in the problem formulation. The analysis is performed using the computer programs DNG6 and DNG7.It can be seen that the transverse shear contributes considerably to lowering the natural frequencies of the flexural vibration modes, and the inclusion of warping considerably increased the natural frequencies of the torsional-dominant vibration modes.