【作者】 林凯；

【导师】 李黎；

【作者基本信息】 华中科技大学 ， 结构工程， 2007， 硕士

【摘要】 随着现代交通体系的快速发展,曲线梁桥得到越来越多的应用。由于曲线梁桥相对与直线梁桥的复杂性与独特性,其抗震设计方法还不完善。本文对隔震曲线梁桥三维地震反应进行了研究,主要包括以下几个内容:首先,对三维地震动随机过程进行谱特征正交变换,在空间某点定义了一组地震动谱主分量,三个地震动谱主分量在任意时间差时互不相关,利用谱主分量间互不相关的性质,推导出三维地震动随机模拟公式;可以假定某一点上在任意时间差时互不相关的谱特征分量在两点间也互不相关,依此假定建立了两点间不同分量的相干函数模型。其次,给出曲线坐标系下的隔震曲线梁桥有限元建模方法。首先利用计入翘曲影响的每结点八自由度的曲梁单元,推导出桥墩单元的刚度矩阵、质量矩阵和三个方向地震质量矩阵。然后使用可以模拟铅芯叠层橡胶支座的双向耦合效应的微分型恢复力模型,并用四阶龙格-库塔方法模拟铅芯橡胶支座单元恢复力,由此可得到支座单元的切向刚度矩阵。最后,编制MATLAB有限元程序与地震动模拟程序,计算某不隔震与隔震三跨连续曲线梁桥在三维地震与单维地震作用下的反应。计算结果表明:相对在单维地震作用下结构地震反应,在三维地震作用下结构可能产生更大地震反应,因此计算曲线梁桥地震反应时应考虑三维地震作用。更多还原

【Abstract】 As the development of moderm traffic system, curved bridges are adopted more widely. For the complexity and the particularity, research of seismic design of curved bridges is still faultiness. This thesis presents a seismic response study of curved bridges under three-dimensional earthquake excitations. And the major content is as follows:Firstly, apply the Proper Orthogonal Decomposition of the ground motion processes in the form of a spectral proper transformation (SPT), and the SPT of the 3-V 1-D ground motion processes at each point of the space defines a new set of ground motion processes components, called spectral proper components and uncorrelated for any time lag. Assuming, as seems physically reasonable, that principal components uncorrelated at one single point remain uncorrelated in different points, makes it poffible to obtain a new model of the tow-point coherence function of the different seismic ground motions components so as to complete the statistical model of the 3-V, 4-D seismic ground motions. Embedding the spectral principal components in a Monte Carlo framework, makes this model very attractive for the digital simulation of seismic ground motion.Secondly, to include the warping effect the curved beam element with eight degrees of freedom is utilized. The element stiffness matrix, element mass matrix and seismic mass matrix in three directions for both girder and pier elements have been derived. The bilateral coupled restoring force model of lead rubber bearings is introduced, and the element stiffness matrix for the bearing element can be derived from this model by the Runge-Kutta method.Finally, MATLAB program is compiled to conduct time history analysis of a three-span, continuously curved girder bridge under earthquake. Comparisons are made between three-dimensional and single-dimensional responses. It is shown that: the internal forces of structure under the three-dimensional earthquake excitation may be larger than that under the one-dimensional excitation, and seismic analysis considering three-dimensional earthquake motion must be performed for the curved grider beam.更多还原