【作者】 毛建猛；

【导师】 谢礼立；

【作者基本信息】 中国地震局工程力学研究所 ， 防灾减灾工程及防护工程， 2008， 博士

【摘要】 如何选择合适的工程结构抗震分析和设计方法一直是地震工程领域引人关注的重要问题。随着基于性态抗震设计思想的提出和发展,作为一种简化的实现性态设计分析的方法,Pushover方法引起了广大学者和工程人员的兴趣,并得到了广泛的研究。本文针对以往Pushover方法的研究中存在的缺点和不足,对Pushover方法进行了改进,主要包括对模态Pushover方法的改进、对钢筋混凝土框架结构Pushover位移反应的修正、Pushover荷载模式与结构性态指标相关性的探讨、基于模态Pushover分析方法确定结构滞回耗能计算四个方面的问题。本论文主要研究内容和成果包括以下几个方面:1.模态Pushover分析方法的一个重要假定是,结构在强震作用下进入非线性状态时,作用于结构的Pushover荷载模式保持不变;可是众所周知,结构发生屈服后,结构的动力特性会发生改变,结构遭受的地震荷载也会发生变化,因此各阶振型采用固定不变荷载模式的模态Pushover方法存在不足。本文提出将结构的第一振型荷载模式改进为两阶段加载模式,高阶振型荷载模式保持固定不变,对结构进行改进的模态Pushover分析。2.建议了一种计算钢筋混凝土框架结构动力弹塑性位移反应的简便方法。通过对5个不同高度的钢筋混凝土框架结构在四类场地上80条地震动作用下的动力和静力弹塑性位移反应进行统计分析,给出了结构由静力弹塑性方法得到的目标位移估计动力时程方法得到的目标位移的修正公式。结果表明:场地条件对钢筋混凝土框架结构静力弹塑性位移反应和动力时程位移反应之间的关系影响显著;对于II类和III类场地,可以直接采用结构的静力弹塑性方法计算结果替代动力时程计算结果;对于I类场地和IV类场地,须采用修正公式对结构的静力弹塑性结果进行修正。3.通过对4个不同高度的钢筋混凝土结构,分别进行了中等硬度场地上15条地震动作用下的非线性动力时程分析和不同荷载模式下的静力弹塑性分析,求解了结构的几个重要反应指标,包括能力曲线、顶端位移角及层间位移角、以及塑性铰分布,探讨了不同荷载模式对钢筋混凝土低层和高层结构反应指标的影响程度,建议了适用于钢筋混凝土低层和高层结构的Pushover荷载模式。4.提出基于模态Pushover分析的结构滞回耗能计算方法。首先采用模态Pushover分析计算结构各阶模态单自由度体系的特征参数,然后计算结构各阶模态单自由度体系对应的滞回耗能,并将其进行线性组合进而确定结构的滞回耗能,并与结构通过动力时程分析计算得到的滞回耗能进行比较,从而给出一种物理概念简单、计算操作方便的确定结构滞回耗能的方法。另外,为了便于计算结构各阶模态单自由度体系的滞回耗能,本文选取了国内外四类场地土上总计320条强震记录作为地震记录数据库,在统计分析的基础上,给出了对应于不同场地土和不同烈度区的单自由度体系等强度滞回耗能设计谱。更多还原

【Abstract】 How to select the adequate procedure for seismic analysis and design of structures is an essential problem in earthquake engineering field. With the development of Performance-based Seismic Design, Pushover Analysis procedure has attracted many scientists’and engineers’attentions and been widely used for its conceptual simplicity and computational attractiveness. To overcome the limitation of Pushover Analysis procedure, some improvements on this procedure were performed in this paper, including the improvement on Modal Pushover Analysis, the revision of target displacement from the pushover analysis for reinforced concrete frame, the correlation of structural response parameters with different lateral load patterns, and the computation of the structural hysteretic energy based on Modal Pushover Analysis etc. The main contents of this dissertation are as follows.1. There is an important assumption that the pushover load patterns keep unchanged even after the structure yields in Modal Pushover Analysis procedure. Recognized the adoption of invariable lateral force distributions in the Modal Pushover Analysis procedure, an improved modal pushover analysis procedure is presented in this paper to estimate the seismic demands of structures, considering the redistribution of inertia forces. It is suggested that after establishing the idealized bilinear curve, a pushover analysis is once again conducted for the first mode in two phases: before and after the structure yields. For the two phases, the structural elastic natural mode and the floor displacement vector at the initial yielding point are used as the displacement shape vector, respectively.2. The approximately estimating method of displacement of reinforced concrete (RC) frame from static pushover analysis (POA) is developed with that from non-linear response history analysis (RHA). Based on the statistic analyses of the RHA and POA results for five RC frames with different height under 80 ground motions recorded at four site conditions, the revised formula of displacements from POA is presented from RHA. The results show that the site soil condition has an important effect on the relation between RHA and POA response results. And the POA results for I and IV site condition should be revised with the formula given in this study while the POA results for II and III site condition can be approximately considered as same to the RHA results.3. The RHA under 15 ground motions recorded on the medium site condition and POA with different lateral load patterns are performed for four RC structures with different height. Several important response quantities are obtained from the RHA and POA, including capacity curves, top displacement ratios and story drift ratios, and location of plastic hinges. The influence of different load patterns on the structural performance demands is discussed for the low- and the high-wise structures. And the rational load patterns for the low- and the high-wise structures are also suggested.4. A simple procedure is presented in this paper for estimating hysteretic energy demands of MDOF systems based on the modal pushover analysis (MPA). Firstly, the characteristic parameters of the modal SDOF systems of structures are computed, and the hysteretic energy is calculated for the modal SDOF systems, then the hysteretic energy demand of structures is obtained by combining these modal demands. In addition, with statistic results of nonlinear analysis of SDOF for 320 ground motions recorded at four site conditions, the equal-strength hysteretic energy design spectra are presented for different site condition and intensity regions.更多还原