cable-stayed bridge
1．Abstract
A comparison on nonlinear analysis of a highly redundant cable-stayed bridge is performed in the study. The initial shapes including geometry and prestress distribution of the bridge are determined by using a two-loop iteration method, i.e., an equilibrium iteration loop and a shape iteration loop. For the initial shape analysis a linear and a nonlinear computation procedure are set up. In the former all nonlinearities of cable-stayed bridges are disregarded, and the shape iteration is carried out without considering equilibrium. In the latter all nonlinearities of the bridges are taken into consideration and both the equilibrium and the shape iteration are carried out. Based on the convergent initial shapes determined by the different procedures, the natural frequencies and vibration modes are then examined in details. Numerical results show that a convergent initial shape can be found rapidly by the two-loop iteration method, a reasonable initial shape can be determined by using the linear computation procedure, and a lot of computation efforts can thus be saved. There are only small differences in geometry and prestress distribution between the results determined by linear and nonlinear computation procedures. However, for the analysis of natural frequency and vibration modes, significant differences in the fundamental frequencies and vibration modes will occur, and the nonlinearities of the cable-stayed bridge response appear only in the modes determined on basis of the initial shape found by the nonlinear computation.
1.摘要
一個拉索高度超靜定的斜拉橋的非線性分析比較在研究中被實(shí)行。 包括橋的幾何學(xué)和預(yù)應(yīng)力分配的初始形狀是使用雙重迭代的方法決定的,也就是,一個平衡迭代和一個形狀迭代。對于開始的形狀分析，一個線性和一個非線性計(jì)算程序被建立。以前斜拉橋所有非線性被忽視，而且形狀迭代是不考慮平衡而實(shí)行的。后來橋的所有非線性被考慮到，而且平衡和形狀的重復(fù)都實(shí)行了?；谑諗坑谝稽c(diǎn)的起始形狀由不同的程序決定,自振頻率和震動模態(tài)也被詳細(xì)地研究。數(shù)字的結(jié)果表明收斂于一點(diǎn)的起始形狀能由二個環(huán)的重復(fù)方法快速地得到,合理的起始形狀能由線性的計(jì)算程序決定，而且那樣許多計(jì)算工作將被節(jié)省。在由線性的和非線性計(jì)算程序決定的結(jié)果之間的幾何學(xué)和預(yù)應(yīng)力分配中只有很小的不同。然而，對于自振頻率和震動模態(tài)的分析來說，基本的頻率和震動模態(tài)將會有顯著的不同，而且斜拉橋反應(yīng)的非線性只出現(xiàn)在由非線性計(jì)算得到的初始形狀的基礎(chǔ)之上的模態(tài)中。