| Summary: | 碩士 === 中原大學 === 土木工程學系 === 88 === A comparison study on static and dynamic analysis of cable-stayed bridges is performed in the study. The initial shapes including shape geometry and prestress distribution of the bridge are first determined by using a two-loop iteration method, i.e., equilibrium iteration loop and shape iteration loop. For the initial shape analysis a linear computation procedure and a nonlinear computation procedure are set up. In the former all the nonlinearities of cable-stayed bridges are disregarded and the shape iteration is carried out without considering equilibrium iteration. In the latter all the nonlinearities of the bridges are taken into consideration and both the equilibrium iteration and the shape iteration are carried out. Based on the convergent initial shapes determined by the different computation procedures, the static deflection and the natural frequencies and vibration modes are then examined in details. Three small cable-stayed bridges with different types are first studied and then the Kao-Ping-Shi cable-stayed bridge, constructed in 1999 in Kaohsiung, Taiwan, is examined. Numerical results show that a convergent initial shape can be found rapidly by the two-loop iteration method, and a reasonable initial shape can be determined by using the linear computation procedure and a lot of computation efforts can thus be saved. There exists only a little bit difference in geometry and prestress distribution between the results determined by linear and nonlinear computation procedures. For static deflection analysis under normal traffic loading, there is no significant difference between the results of linear and nonlinear analysis. But, for the analysis of natural frequency and vibration modes, significant difference in the fundamental frequency and vibration modes can be seen and the nonlinearities of cable-stayed bridges appear only in the modes determined based on the initial shape found by the nonlinear computation procedure.
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