跨断层深水斜拉桥非线性地震响应特性及损伤评估

发布时间：2018-03-31 12:39

本文选题：跨断层地震　切入点：深水斜拉桥　出处：《北京交通大学》2016年硕士论文

【摘要】：断层错动是地震形成的主要原因,国内外抗震规范给出了结构物避让活动断层的距离及跨越建议措施。由于地形、地貌的限制,或选线设计及建设成本等的约束,采用桥梁形式跨越活动断层在所难免。近些年来的数次大地震中,多座跨断层桥梁发生严重破坏或垮塌。目前,国内外对跨断层桥梁抗震设计的问题仍处于初始研究阶段,相关文献资料较少,相关规范条例缺乏。随着越来越多的桥梁结构在高烈度区建设,开展跨断层桥梁的抗震研究具有重要的现实意义。本文以某跨断层大跨度深水斜拉桥为背景,对跨断层地震动输入、结构地震响应和损伤等问题进行研究。本文的主要研究工作如下：(1)系统梳理了国内外跨断层结构抗震分析的研究现状,总结现阶段跨断层桥梁研究方面存在的问题和不足。根据走滑断层的地震动特征,采用低频脉冲和高频波组合的方式分别合成了不同震级下垂直于断层(FN)方向和平行于断层(FP)方向的地震动,并对比了不同方向跨断层地震动的特征。结果表明,在断层两侧,FN方向地震动大小相等,方向相同,FP方向地震动大小相等,方向相反；FN方向的加速度谱和速度谱的卓越周期均大于FP方向。(2)以某大跨高桩承台深水斜拉桥为研究对象,基于OpenSees平台建立三维非线性精细化模型,并对比分析了土-结构相互作用和入水深度对斜拉桥自振特性的影响。研究表明,斜拉桥前几阶振型均为主梁的振动形态,且自振周期很长；另外,土-结构相互作用和入水深度都会增大斜拉桥自振周期。(3)基于人工合成的跨断层地面运动,在FN方向和FP方向分别采用一致激励法和非一致激励法对深水斜拉桥进行非线性动力分析,分别对比了地震动强度、入水深度、断层跨越角度及断层跨越位置等因素对斜拉桥主塔地震响应和损伤分布的影响。研究表明,在考虑上述因素时,动力响应和损伤指数的最大值均出现在主塔塔底,因此,对于跨断层深水斜拉桥的抗震设计时应特别关注主塔塔底的响应特性。(4)根据断层跨越时不同角度及位置下斜拉桥动力响应和损伤指数的变化规律,提出斜拉桥合理断层跨越角度及跨越位置,为实际工程建设提供理论支持。
[Abstract]:Fault dislocation is the main cause of earthquake formation. The seismic code at home and abroad gives the distance of structures avoiding active faults and the measures for crossing them. Due to the constraints of topography, geomorphology, route selection design and construction cost, etc. It is inevitable to cross active faults in the form of bridges. In recent years, during several large earthquakes, many bridges across faults have been seriously damaged or collapsed. At present, the problem of seismic design of bridges across faults is still in the initial stage of study at home and abroad. As more and more bridge structures are built in high-intensity areas, It is of great practical significance to carry out the seismic research of cross-fault bridges. In this paper, the seismic input of a long-span deep water cable-stayed bridge across faults is taken as the background. The main research work of this paper is as follows: 1) the current situation of seismic analysis of cross-fault structures at home and abroad is systematically reviewed. According to the characteristics of ground motion of strike-slip faults, the existing problems and shortcomings in the research of cross-fault bridges are summarized. The ground motions perpendicular to the direction of fault FN and parallel to the direction of fault FPN are synthesized by the combination of low frequency pulse and high frequency wave respectively, and the characteristics of cross fault ground motion in different directions are compared. The magnitude of ground motion is equal in FN direction and FP direction on both sides of fault. The excellent periods of acceleration spectrum and velocity spectrum in the opposite direction of FN are larger than that in FP direction. Taking a long-span deep water cable-stayed bridge with high pile cap as the research object, a three-dimensional nonlinear refined model is established based on OpenSees platform. The effects of soil-structure interaction and depth of water entry on the natural vibration characteristics of cable-stayed bridge are compared and analyzed. The results show that the first several modes of the cable-stayed bridge are the vibration form of the main beam, and the natural vibration period is very long. Soil-structure interaction and depth of water will increase the natural vibration period of cable-stayed bridge. In the FN direction and FP direction, the nonlinear dynamic analysis of deep water cable-stayed bridge is carried out by using the uniform excitation method and the non-uniform excitation method, respectively, and the intensity of ground motion and the depth of entering water are compared, respectively. The influence of fault crossing angle and fault crossing position on the seismic response and damage distribution of the main tower of cable-stayed bridge is studied. The results show that the maximum of dynamic response and damage index appear at the bottom of the main tower when the above factors are taken into account. For seismic design of deep water cable-stayed bridges across faults, special attention should be paid to the response characteristics of the main tower bottom. (4) according to the dynamic response and damage index of cable-stayed bridges at different angles and positions during fault crossing, the dynamic response and damage index of cable-stayed bridges should be changed. The reasonable crossing angle and location of faults of cable-stayed bridge are put forward to provide theoretical support for practical engineering construction.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U442.55;U448.27

【相似文献】