Seismic response analysis of an irregular base isolated building
Seismic response analysis of an irregular base isolated building
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DOI：
10.1007/s10518-011-9267-1
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发表时间：
2011-04
影响因子：
4.6
通讯作者：
L. Sarno;E. Chioccarelli;E. Cosenza
中科院分区：
文献类型：
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作者：
L. Sarno;E. Chioccarelli;E. Cosenza
本文对采用基础隔震系统（BIS）的不规则建筑进行了符合规范的线性和非线性动力分析，并对分析结果进行了可靠性评估。本文以一大型钢筋混凝土多层框架医院为例，对327个高阻尼橡胶支座进行了综合分析。对结构的三维（3D）有限元模型（FEM）进行了谱和时程（线性和非线性）分析;还对单自由度（SDOF）系统进行了简化分析。结果表明，在损伤极限状态下，三维有限元谱分析计算的最大层间位移（d/h）值在规范限值（d/h = 0.33%）的1/6 ~ 1/10之间，因此，对于带BIS的建筑物，应要求更严格的规范限值。相对于地面加速度（自由场地），最大楼层加速度降低约70%;加速度剖面沿多层框架高度沿着均匀。目前缺乏用于评估BIS建筑设备抗震性能的楼板加速度阈值。在极限状态（ULS）下，谱分析提供的作用和变形值比通过时程分析得出的保守性更低。为了进行可靠的基础隔震建筑物的动力分析，关键是选择符合结构系统的基本振动周期的天然地震地面运动。然而，在世界范围内可用的目录中选择适当的自然强烈运动并不简单;包含BIS的建筑物具有通常高于2.0 s的振动周期。因此，远距离和高震级的地震是有效的基础隔震建筑，然而，这样的地震是罕见的地震数据库。本研究的结果还表明，简化的线性分析往往提供估计的响应量，基础隔震器的位移和基础剪力的上部结构，可以可靠地采用在初步设计阶段。当模态质量参与比大于85- 90%时，三维模型的谱分析结果与单自由度体系的谱分析结果趋于一致，即使对于不规则的上部结构也是如此。单自由度谱分析和三维有限元谱分析的结果都包含了线性时程的结果。
This paper assesses the reliability of code-compliant linear and nonlinear dynamic analyses for irregular buildings with base isolation system (BIS). Comprehensive analyses are carried out for a case study comprising a large reinforced concrete multi-storey framed hospital with 327 high-damping rubber bearings. Spectral and time history (linear and nonlinear) analyses were performed on the three-dimensional (3D) finite element model (FEM) of the structure; simplified analyses were also conducted on single-degree-of-freedom (SDOF) systems. It is found that, at damageability limit state, the values of maximum interstorey drifts (d/h) computed with spectral analyses on the three-dimensional FEM range between 1/6 and 1/10 of the code limit (d/h = 0.33%); thus more stringent code limits should be required for buildings with BISs. The maximum floor acceleration is reduced by about 70% with respect to the ground acceleration (free field site); the acceleration profile is uniform along the height of the multi-storey frame. Threshold values of floor accelerations to assess the seismic performance of equipments in buildings with BIS are lacking. At ultimate limit state (ULS), spectral analyses provide values of actions and deformations that are less conservative than those derived through time history analyses. To perform reliable dynamic analyses of base isolated buildings it is crucial to select natural earthquake ground motions compliant with the fundamental period of vibration of the structural system. Nevertheless, it is not straightforward to select adequate natural strong motions in the catalogues available world-wide; buildings incorporating BISs possess periods of vibration which are generally higher than 2.0 s. As a result, distant and high-magnitude earthquakes are effective for base isolated buildings; nevertheless, such earthquakes are scarce in the seismic databases. The outcomes of the present study also demonstrate that simplified linear analyses tend to provide estimates of the response quantities, displacements of base isolators and base shear of the superstructure, which can be reliably employed at preliminary design stage. Spectral analysis results of the 3D model tend to match those of the SDOF systems, even for irregular superstructure, provided that modal mass participating ratios are greater than 85–90%. The results of spectral analyses on both SDOF and three-dimensional FEM envelope the outcomes of linear time histories.