【作者】 叶昆；

【导师】 方秦汉； 李黎；

【作者基本信息】 华中科技大学 ， 结构工程， 2008， 博士

【摘要】 在常规地震(远场地震或者近断层非脉冲型地震)作用下基础隔震结构具有良好的减震效果,但是近断层地震的明显长周期速度和位移脉冲运动却给基础隔震结构带来了不利影响。目前国内外对基础隔震结构的研究及应用大多是针对常规地震所进行的,对于近断层脉冲型地震对基础隔震结构的影响也有相关的研究,但仍有一些问题缺乏足够的认识。随着基础隔震技术规范化建设的需要,深入研究在近断层脉冲地震作用下基础隔震结构地震响应是十分有必要,这不仅在理论上是对基础隔震理论研究的完善,而且对土木工程结构的地震防护也有着十分重要的现实意义。考虑到铅芯橡胶隔震支座(LRB)是应用最为广泛的基础隔震体系,本文以LRB基础隔震结构为对象,开展了以下几方面的研究工作:(1)系统研究了LRB基础隔震结构在近断层脉冲型地震动作用下的动力反应。提出了基于Masing准则的非迭代时程计算方法,与传统Newton-Raphson迭代算法进行了比较,数值结果表明该非迭代算法能够满足土木工程计算的精度要求;给出更为合理的人工合成近断层脉冲型地震的方法;对LRB基础隔震结构在近断层脉冲型地震作用下的动力反应进行了参数研究。(2)对LRB基础隔震结构在近断层脉冲型地震作用下可能出现的碰撞响应进行了分析。在对文献中已有不同碰撞分析方法或模型进行综述的基础上,提出了既能够合理反映碰撞物理事实又能够易于确定相关参数的改进Kelvin碰撞分析模型,并对其中相关参数的确定进行了理论推导以及数值验证,同时也对Hertzdamp碰撞分析模型中阻尼常数的表达式进行了修正;通过对使用不同碰撞分析模型所进行的LRB基础隔震结构碰撞响应进行比较,表明改进Kelvin碰撞分析模型的可靠性;运用改进Kelvin碰撞分析模型对LRB基础隔震结构碰撞分析后发现,碰撞响应给基础隔震的有效性带来了极其不利的副作用并显著改变了上部结构的振动特性;对影响LRB基础隔震结构碰撞响应的因素进行了参数研究。(3)研究了LRB偏心基础隔震结构在近断层脉冲型地震作用下的动力反应。建立了能够考虑每个LRB隔震支座变形的单层LRB偏心基础隔震结构的计算分析模型和运动方程;提出了人工合成双向近断层脉冲型地震的方法;对比了在近断层脉冲型地震和常规地震作用下隔震层偏心、上部结构偏心、上部结构转侧频率比以及近断层脉冲型地震脉冲周期等重要参数对LRB偏心基础隔震结构侧移扭转耦联反应的影响。(4)研究了LRB偏心基础隔震结构在近断层脉冲型地震作用下的碰撞响应。建立了基于改进Kelvin碰撞分析模型的多层LRB偏心基础隔震结构碰撞响应的计算分析模型和运动方程;根据所建立的计算分析模型进行非线性时程碰撞分析,对比分析了偏心/对称LRB偏心基础隔震结构的碰撞响应和考虑碰撞/不考虑碰撞两种情况下LRB偏心基础隔震结构的扭转反应;探讨了隔震层偏心、上部结构偏心以及上部结构各层转侧频率比对LRB偏心基础隔震结构碰撞响应中上部结构扭转反应的影响。更多还原

【Abstract】 Base-isolated structure shows excellent performance in effectively reducing the damage resulted from the common ground motion (i.e., far-field ground motion or near-fault ground motion without prominent pulse); however, behaves poorly under near-fault ground motion with long period velocity or displacement pulse. At present, most of research related to the base-isolated structures is based upon the common ground motion; on the contrary, the investigation into the effect of near-fault pulse-like ground motion upon the base-isolated structures is limited. In order to realize the application standarization of base-isolated technology in civil engineering, it is necessary to comprehensive study the effect of near-fault pulse-like ground motions on the base-isolated structures, which can be regarded as the beneficial complement of the base isolation theory. Lead Rubber Bearings (LRB) is the most widely used base-isolated system; therefore, LRB base-isolated structure is selected as research object in this dissertation and corresponding study includes the following aspects:(1) systematically study the dynamic response of LRB base isolated structure under near-fault pulse-like ground motions. Non-iterative computational method for tine-history analysis of nonlinear structures is proposed based upon the well-known Masing criteria, after comparison with traditional Newton-Raphson iterative algorithm, it is indicated that the non-iterative computational method based on the Masing criteria can meet the accuracy demand in civil engineering; the more reasonable method to artificially generating near-fault pulse-like ground motions is given; paremetric study on the dynamic the dynamic response of LRB base isolated structure under near-fault pulse-like ground motions is carried out.(2) analyzing the possible pounding response of LRB base isolated structure under near-fault pulse-like ground motions. Based upon the evaluation of some commonly used impact analytical models, the modified Kelvin impact analytical model, which can reasonably account for physical nature of pounding phenomena and time facilitate the determination of relevant parameters, is for the first time put forward, theoretical derivation of expressions of relevant parameters and corresponding numerical verification are conducted, at the same time, the corrected expression for damping constant in the Hertzdamp impact analytical model is given; Comparison of pounding response of LRB base-isolated structures obtained by using various impact analytical models is made, which validate the modified Kelvin impact analytical model; After analyzing the pounding response of LRB base-isolated structures with adjacent structures using the modified Kelvin model, it can be observed that occurrence of pounding has adverse effect on the LRB base-isolated structure and significantly changes the vibration modes of superstructure; parametric research on some factors influencing the pounding response of LRB base-isolated structures is made.(3) conducting the research on the seismic response of asymmetric LRB base-isolated structrures under near-fault pulse-like ground motions. Analytical model and motion of equation of single-storey asymmetric LRB base-isolated structure, which can incorporate deformation of each LRB, is built; procedures to synthetically simulating bi-directional near-fault pulse-like ground motions is developed; comparative study on the seismic response of asymmetric LRB base-isolated structures under either near fault pulse-like ground motions or common ground motions is carried out; effect of isolation eccentricity, superstructure eccentricity, ratio of torsional-to-lateral frequency of superstructure and pulse period of near-fault pulse-like ground motions on the seismic response of asymmetric LRB base-isolated structures is analyzed.(4) investigating the possible pounding response of asymmetric LRB base-isolated structure subject to near-fault pulse-like ground motions. Analytical model and motion of equations of multi-stories asymmetric LRB base-isolated structure in the case of pounding with adjacent structrures is developed. Comparative study of pounding responses between symmetric and asymmetric LRB base-isolated structures is carried out, at the same time, comparison of torsional response of asymmetric LRB base-isolated structures in the case of both pounding and no pounding with adjacent structures, is made; discussion on the effect of isolation eccentricity, superstructure eccentricity, ratio of torsional-to-lateral frequency of indivisual story in the superstructure on the torsional response of superstructure in the case of pounding of asymmetric LRB base-isolated structures with adjacent structures.更多还原