Dynamic characteristics of elastic beams subjected to traffic loads

The objective of this study is to investigate the dynamic behavior of elastic beams subjected<br />to moving loads. Although analytical methods are available, they have limitations with respect to<br />complicated structures. The use of computer technology in recent years is an effective way to solve the<br />problem; thus using the latest technology this study establishes a finite-element solution procedure to<br />investigate dynamic behaviors of a typical elastic beam having a set of constant geometric properties and<br />various span lengths. Both the dead load of the beam and traffic load are applied in which the traffic load<br />is considered a concentrated moving force with various traveling passage speeds on the beam. Dynamic<br />behaviors including deflection, shear, and bending moment due to moving loads are obtained by both<br />analytical and finite element methods; for simple structures, they have an excellent agreement. The<br />numerical results show that based on analytical methods the fundamental mode is good enough to<br />estimate the dynamic deflection along the beam, but is not sufficient to simulate the total response of the<br />shear force or the bending moment. The linear dynamic behavior of the elastic beams subjected to<br />multiple exciting loads can easily be found by linear superposition, and the geometric nonlinear results<br />caused by large deformation and axial force of the beam are always underestimated with only a few<br />exceptions which are indicated. In order to make the results useful, they have been nondimensionalized<br />and presented in graphical form.