Bridge dynamic interaction and optimum design

A formulation, a solution algorithm, and a numerical implementation scheme are developed and presented for accurate analysis of vehicle-bridge dynamic interaction problems, as well as for optimum design of bridge structures subjected to general traffic conditions. The finite element-based formulation and solution algorithm take into account the dynamic interaction between the bridge and vehicles, and among the vehicles, as well as the effects of multiplicities of vehicles, traffic lanes, and traversing directions. Furthermore, the realistic analysis algorithm, which is based on the numerical method of lines, is capable of considering various types of bridges, and arbitrary bridge geometry and configuration, as well as bridge roadway surface irregularities. The Newmark method in connection with a multi predictor-corrector scheme is employed to obtain accurate results of bridge dynamic response.;The consideration of the bridge structure as an integrated system in the design process necessitates the use of a multilevel optimization technique. By using this technique, the problem is decomposed into three sublevels: (1) component level, (2) structural level, and (3) configuration level. The optimization is carried out in an iterative manner in connection with structural response and design sensitivity analyses to preserve the coupling among the sublevels.;The formulation and the solution scheme are implemented into a computer program developed for this investigation. A computer graphics module is incorporated into the computer program to display interactive dynamic response of the bridge and the vehicles traversing the structure. The preprocessing capabilities of the program include on-screen display of the configuration and finite element mesh of the bridge. A number of illustrative optimum design and analysis example problems are solved using the computer program in order to verify the validity and efficiency of the formulation and solution algorithm. Based on the numerical results, technical as well as practical conclusions concerning dynamic response and optimum design of bridge structures are presented and discussed.