Dynamic analysis of highway bridges under moving vehicles

A continuum approach is presented for the dynamic analysis of different types of bridges for the vehicular movement. The types of bridges include truss bridge, cantilever bridge, arch bridge, multispan slab-and-girder bridge, cable-stayed bridge and suspension bridge. The formulation is first presented for a single moving load for which the dynamic response at any given point of time is obtained in terms of few recursive closed form expressions in each mode of vibration. The results of this analysis is then utilized for obtaining the response for single or multiaxle moving load idealized as a single, two-dimensional and three-dimensional sprung mass system. Mode shapes and frequencies of the continuum are extracted from eigen value problem which is determined from the dynamic stiffness of the system under various kinds of support and boundary condition consistent with the type of the bridge. In order to make the solution procedure applicable to different types of bridges, each type of bridge is suitably idealized. The analysis considers the vehicle-pavement interactive force idealized as both linear and nonlinear (of hysteretic type), the effects of torsional coupling and random irregularity of the deck surface. The random bridge profiles are synthetically generated from specified power spectral density function of the pavement profile. The response of the 'bridge is obtained in time domain utilizing an iterative procedure to account for the nonlinear interactive force. For the dynamic response of cable-