【作者】 张行；

【导师】 李黎；

【作者基本信息】 华中科技大学 ， 结构工程， 2010， 博士

【摘要】 在我国刚构桥仅仅有二十年的发展历程,作为山高谷深、地形复杂山区的首选桥型,其在抗震救灾等各种情况下扮演着重要生命线工程的角色。由于其跨径长、墩高差异大,结构动力特性及地震反应特点相对一般桥梁更为复杂,因此特别需要对其抗震性能进行研究。高墩刚构桥的抗震研究对同类桥梁的抗震设计及评估意义重大。本文对大跨度刚构桥的动力稳定性能进行了研究,主要包括第一类动力稳定(弹性稳定)计算理论和实例分析、刚构桥的非线性模拟方法、混凝土和钢筋的材料参数的确定、全桥及高墩的第二类动力稳定(非线性稳定)研究等几个部分。具体包括以下几点。1)通过查阅大量有关刚构桥的稳定问题、抗震研究以及实际工程结构的动力稳定研究现状的国内外文献,总结了刚构桥动力稳定研究的两个主要问题是：稳定性判别准则和求解方法。针对这两个问题提出了采用基于Liapunov运动稳定性理论的稳定性判别准则来进行刚构桥的动力稳定判别和通过数值求解方法来解决复杂结构在复杂地震动作用下的动力稳定问题的研究思路。2)为了确定符合本工程的钢筋和混凝土的材料参数,并评判刚构桥在地震作用下动力失稳时的性能水准,通过研究地震作用下钢筋混凝土桥墩的五种损伤状态——构件屈服、混凝土保护层压碎、混凝土保护层剥落、纵向钢筋屈曲和结构极限状态,确定了本工程对应的钢筋和混凝土的五级应变。3)刚构桥数值模拟的关键是如何考虑恰当的结构的非线性,而这一问题一直是刚构桥静力和动力分析中研究的难点和热点问题。选取纤维模型这一模拟钢筋混凝土材料非线性最精细的方法来模拟刚构桥的非线性性能,编写了矩形空心墩的纤维截面代码,并对高墩进行了非线性静力分析。4)通过基于纤维模型的龙潭河最大高墩和全桥在地震作用下的非线性IDA计算,解决了复杂结构在地震作用下,从初始激振、非线性振动直到失稳破坏的全过程模拟和动力失稳判别问题。根据B-R准则给出了其临界地震加速度幅值,并对其动力性能和特征响应指标进行了深入的探讨。更多还原

【Abstract】 Recently Rigid-Frame Bridges have been built for only twenty years in our country and they have been used as the preferred bridge type in coplicated terrain mountain areas. They play important role as lifeline engineering in certain cases such as earthquake relief and so on. Therefore study on their seismic performance needs to be carried out, especially on their dynamic stability under earthquake action. Dynamic stability of a rigid-frame bridge has been investigated in this dissertation, and the seismic performance of the bridge is evaluated. The research of seismic response of rigid-frame bridge with high piers is of great significance to the seismic design and evaluation of other similar bridges.In this dissertaion, the studies on the dynamic stability of rigid-frame bridge with high piers are performed. The research content includes:the theory and example analysis of the elastic dynamic stability; the nonliear simulation method of bridge piers; the material parameters of reinforcement and concrete; the nonlinear dynamic stability of high pier and full bridge. The specific contents are as follows,1) Based on the massive domestic and international literature of the seismic response, static stability resarch and dynamic stability of rigid-frame bridges, summarizes the two key points of the research on the dynamic stability of rigid-frame bridge:what is the suitable and practical dynamic criteria and how to solve the dynamic stability of the bridge. The criteria based on Liapunov’s motion stability theory and numerical simulation method are put forward to solve the dynamic stability of comples structures under earthquake. And the key point of the numerical simulation of rigid frame bridge is how to deal with the nonlinearity of the structure.2) In order to determine the reinforcement and concrete matrrial parameters which are suitable for this bridge, the strain corresponding to five damage states is investigated, which can also be used to evaluate the performance levels of the bridge under earthquake. The five damage states of the bridge piers subjected to seismic action are:members yielding, concrete cover crushing, concrete cover spalling, bar buckling, structure limit state respectively.3) Due to the challenging nature of accurately modeling the material nonlinearity of both steel reinforcement and concrete, conducting nonlinear static and dynamic analysis of the rigid frame bridge with high pier remains as a significant difficulty. The fiber model is choosed to model the nonlinearity of the rigid-frame bridge which is the most precise and latest method. The section code is developed and the nonlinear static analysis is done to the piers.4) The nonlinear IDA is done to the full bridge and piers based on the fiber model under earthquake action. The whole process of the structure from initial exitation, nonlinear vibrating to instabe failure is simulated. During the analysis B-R criteria is used to judge the critical load of the bridge. The dynamic performance and instablility mechanism of the bridge are researched.更多还原