Dynamic characteristics of elastic beams subjected to traffic loads

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