【作者】 吴平川； 魏翠玲； 高春华；

【Author】 Wu Pingchuan Wei Culling Gao Chunhua (Hebei Engineering of University Handan 056038,P.R.China)

【机构】 河北工程学院；

【摘要】 在强烈地震作用下,结构将进入弹塑性阶段,结构的刚度随之发生变化,并出现塑性内力重分布。弹性静力法概念简单,忽略了结构的动力特性和结构的非刚性等重要特性,只适用于固有周期很小的结构,对多高层和具有一定柔性的结构会产生较大的误差,反应谱法能考虑结构的动力特性及其与地震作用之间的相互关系,但它不能给出结构弹塑性变形阶段的内力和变形状态,为了研究和计算高层建筑结构的弹塑性变形,有必要进行结构的弹塑性分析。弹塑性分析分为弹塑性动力分析和弹塑性静力分析两大类,弹塑性动力分析计算过程复杂,结果处理繁杂,工作量大,其结果很大程度上受到所选地震波的影响,因此在工程抗震设计中没有得到广泛的应用。弹塑性静力分析方法又称 Push-over 方法,目前被认为是最具有广泛应用前景的弹塑性地震反应简化分析方法。 Push-over 的分析结果在很大程度上依赖于水平荷载分布模式,常用的水平分布模式有均匀分布、倒三角分布等,不同的分布模式得到的结构能力曲线差异较大,一般来说,采用倒三角分布的水平侧向力时,只考虑了对应基本振型的地震作用,忽略了高阶振型的影响,而实际结构的位移向量是由多阶振型共同决定的,尤其是长周期结构,高振型对结构的地震作用效应是不可忽略的。为了考虑高阶振型的影响、结构屈服后惯性力的重分布以及振动特性的变化,一些学者针对常规的 Push- over 方法进行了改进,Chopra 和 Geol 提出的模态 Push-over 法就是其中一种较好的改进,这种方法概念简洁,在估算结构地震需求方面具有较好的精度。本文采用模态 Push-over 方法针对建筑结构进行分析,并与常规的 Push-over 方法做比较,结果表明:该方法具有较高的精度,其在基于性能的抗震设计中具有较好的应用前景。更多还原

【Abstract】 The structure will respond beyond the elastic limits when subjected to strong earthquake.The stiffness of it will alter and the redistribution of forces will occur.The linearly elastic procedure with conception simplicity that neglects the dynamic characteristic of structure can only be used when the natural period of the structure is very small.Although the response spectrum method can consider the dynamic characteristic of the structure and the relationship between the earthquake and structure,it can’t provide the forces and deformation of the structure which beyond the elastic limits.It is evitable to make inelastic analysis in order to study the inelastic response of tall buildings.Inelastic analysis can be categorized nonlinear time-history analysis and nonlinear static analysis. The former is complicated and time-consuming and the analytical result tend to highly sensitive to the earthquake input.This makes it inappropriate in daily engineering.Simplified nonlinear static analysis (pushover analysis) is considered to be the most prospective method in future.The analytical results of pushover analysis largely depend on the lateral load distribution.The common used pattern include:①inverted triangle distribution;②uniform distribution.Different load distribution can provide different capacity curves.Generally,the inverted triangle distribution only considers the fundamental mode.In fact,the displacement profile is decided by several modes especially for the structure with longer period.The impact of higher mode on the structure is negligible.To consider the higher modes and the redistribution of force,researchers have made some improvement on traditional pushover analysis.The modal pushover analysis (MPA) suggested by Chopra and Goel is a significant improvement.The MPA with conception simplicity have higher precision in evaluating the earthquake demand of the structure.In this paper,the MPA is used to analyze a structure and compared with the conventional pushover method.The results indicate that the MPA have higher precision and can be used to serve the performance-based seismic design.更多还原