【作者】 孙立；

【导师】 周锡元；

【作者基本信息】 北京工业大学 ， 结构工程， 2005， 硕士

【摘要】 桥梁结构作为生命线工程的重要组成部分,是公路、铁路交通系统的关键设施,而地震则是危害人类社会的一大自然灾害。每次大的地震都造成了或多或少的桥梁结构破坏,不但造成了直接的经济损失,也严重影响了震后救灾恢复生产。现有的桥梁设计规范采用的反应谱抗震分析方法,只考虑一致地震激励的影响,而实际地震过程中,由于震源、地震波传播路径、局部场地条件等的差异导致了桥梁各支承点的实际地震动是不同的,所以有必要对桥梁结构进行多点激励分析。对于结构抗震分析来说,地震动输入、结构自身特性、结构反应的评价是主要的三个环节。本文从这三个环节出发,对多点激励输入方式对连续刚构桥的影响进行了分析,主要工作与成果有: 1、研究改进了符合多点激励要求的地震动模拟方法。良好的地震动描述是结构分析的基础,本文研究了多点激励地震波的模拟方法,对自功率谱模型、互相干函数、强度包线函数等模拟过程使用到的参数与模型进行了讨论,并给出了模拟实例。2、多点激励地震反应分析方法的研究。本文对时程分析法、随机振动分析法、多点反应谱法进行了总结,比较了彼此的优缺点。研究和讨论了加速度输入与位移输入多点激励动力平衡方程式的实际应用。3、就行波效应、不相干效应、局部场地条件效应对连续刚构桥地震反应的影响进行了详尽的分析,得到了影响规律。4、就多点激励下连续刚构桥反应与一致激励下连续刚构桥反应进行了对比,结果发现:(1)行波效应对于连续刚构桥影响显著;(2)不相干效应影响不明显;(3)局部场地效应由于不同支承点输入的地震动相位差异,因而互相影响导致整体反应较低,不如一致激励反应大。从而说明连续刚构桥设计一定要考虑行波效应的影响,可以忽略不相干效应,而对于局部场地条件效应要根据真实工程场地与桥跨布置的不同做具体的分析。更多还原

【Abstract】 Bridges are vital elements of the economic functioning of modern societies. As one of the most devastating natural disaster, earthquakes always cause tremendous losses of life and property. In the event of an earthquake, failure or even damage of a bridge can pose a significant life hazard, and cause difficulties in the emergency response to the earthquake as well as in subsequent recovery activities. Seismic ground motions can vary significantly over distances which are of the same order of magnitude as the dimensions of some extended structures, such as bridges. Three phenomena are responsible for these variations: (1) the difference in the arrival times of seismic waves at different stations; (2) the loss of coherency of the motions due to reflections and refractions of the waves in the heterogeneous medium of the ground, as well as due to the difference in the manner of superposition of waves arriving from an extended source at various stations; and (3) the difference in the local soil condition at each station and the manner in which they influence the amplitude and frequency content of the bedrock motion. Recent analyses with array recording have shed light on the nature of these effects and their relative importance. It is important to develop reliable methods for predicting the performance of new bridge designs and for evaluating the existing structures. It is known that, under realistic conditions, the variations in the support motions can significantly influence the internal forces generated in the structure. While in most cases the magnitudes of these forces are reduced, there are situations where the variations in the support motions may result in larger internal forces. It is important for a better understanding of this phenomenon, and for the development of practical analysis methods that can accurately account for its effects. The main contents of this dissertation are described as follows: 1. The simulation of multipoint earthquake wave. The suitable earthquake wave is very important for the analyses of structure. In this paper, the method to simulate multipoint earthquake wave is systematically studied. The simulating更多还原