【作者】 范振华；

【导师】 张谢东；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2013， 博士

【摘要】 近年来我国墩高超过100米的超高墩刚构桥发展迅速,是当前桥梁工程的重要前沿。然而近年来发生的几次大震中,不乏桥梁结构的倒塌事故,造成了巨大的人员伤亡和经济损失。超高墩刚构桥抗震安全,尤其是地震作用下抗倒塌能力成为亟待解决的重要课题。针对目前我国桥梁结构的抗震设计思想——“小震不坏、中震可修、大震不倒”,开展大型桥梁结构的倒塌分析、倒塌极限状态点的确定等有关倒塌问题的研究具有重要的现实意义。目前复杂结构的倒塌分析主要借助数值模拟的方法进行,准确建立结构的分析模型是倒塌分析要解决的首要关键问题。其次,合理的倒塌判别准则也是研究结构倒塌问题需要解决的关键问题,现有的倒塌判别准则主要是针对规则桥梁,对于动力响应复杂的超高墩刚构桥还需要专门进行研究。第三,结构在使用过程中由于环境或者其他因素不可避免的存在不同程度的劣化情况,不考虑这一因素,实际上只是对拟建结构的评估,因此,进行倒塌分析还要考虑结构在服役期间的劣化。本文首先对国内外研究现状进行了总结,指出了超高墩桥梁结构倒塌分析需要解决的关键问题。其次,提出了考虑纵筋屈曲的方法,并通过钢筋混凝土构件拟静力试验的数值模拟分析,研究了纵筋屈曲对构件后期破坏阶段的模拟的影响；研究结果表明所提出的方法能有效考虑试件在加载后期由于纵筋屈曲而导致强度和刚度的退化现象。第三,提出了超高墩刚构桥倒塌判别准则,建立了超高墩刚构桥基于单地震动IDA的倒塌分析方法,并运用该方法对一典型工程实例进行了倒塌全过程分析,探讨了超高墩刚构桥的破坏模式和倒塌机理；研究结果表明,纵向钢筋屈曲对超高墩刚构桥的倒塌性能影响很大,超高墩刚构桥在地震作用下的倒塌破坏模式为桥墩截面多处同时形成塑性铰的竖向倒塌破坏,所提出的基于墩顶竖向位移的倒塌判断准则适用于周期长、高阶振型贡献大的高柔桥梁。第四,研究了劣化对结构抗倒塌能力的影响,主要考虑了混凝土剥落、钢筋截面减少、和钢筋强度降低对超高墩刚构桥抗倒塌能力的影响；研究结果表明劣化对结构的自振周期和抗倒塌性能有影响。第五,在单地震动倒塌分析的基础上进行了多地震动倒塌分析,即倒塌易损性分析；研究表明考虑结构劣化的地震倒塌易损性分析能反映结构抗地震倒塌破坏的实际能力。本文研究工作可为超高墩刚构桥基于性能的抗震设计和地震倒塌研究提供参考。更多还原

【Abstract】 In recent years, there are many long span rigid bridges with super high rise piers more than100meters have been built in China. They play important role as lifeline engineering in certain cases such as earthquake relief and so on. Research on these bridges is one of the most important frontiers of bridge engineering. Moreover, several earthquakes have made huge casualties and enormous financial loss in China, in which many bridges collapsed and exaggerated the disaster. Avoiding bridges collapse is an important mission in seismic design and has been paid more attention after the earthquake took place in Wenchuan2008. Based on the popular seismic design method "bridges after small earthquakes could be used continuously; bridges after middle earthquakes could be repaired; bridges after huge earthquakes could be stand as usual" researches on the collapse limiting condition and collapse analysis in bridges have a practical significance to ensure a safe life.Numerical simulation is the main method to analysis the collapse of the complex structure. The first key point is to build an accurate model to analyse the collapse of structure; the second is to set up a precise collapse criterion for the rigid frame bridges with super-long piers based on dynamic response; the third ont is to simulate the effects of the surroundings and other negative factors during the bridge service period.In this dissertation the present research status at home and abroad and the key points of research on callapse of the rigid frame bridge with super high rise piers are introduced in Chapter1. In Chapter2the method of modeling the buckling of longitudinal reinforcement is presented and verified by the pseudo-static tests. The results show that in order to model the degradation in strength and stiffness of RC columns loaded to their failure, the buckling of reinforcements should be taken into account in simulation. In Chapter3the criterion of collapse based vertical displacement of pier top for rigid frame bridge with high piers is proposed and verified by an engineering example. It is demonstrated that the proposed criterion is effective in evaluating the collapse of the structure, and the failure mode of the structure is vertical callapse with several plastic hinge appeared simultaneously in the bridge piers. In Chapter4the effects of deterioration on the callapse ability including spalling of concrete cover, deceasing of steel areas and strength are investigated in depth. It is shown that the deterioration will result in the change of period and collapse capacity of the structure. In Chapter5, the collapse fragility of the bridge under multiple ground motions is investigated. It is illustrated that the deterioration should be taken into account to reflect the real collapse capacity. Finally in Chapter6the full summary and the future research work are given.This study will be a reference for seismic design and earthquake collapse analysis of these rigid frame bridges with super high rise piers.更多还原