对房屋抗震评估中采用的非线性静力分析方法的评估
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摘要
基于设计的性能分析方法的一个关键部分是,对地震需求谱参数的准确采用。非线性静力方法(NSPs)现在广泛应用在工程实践上,主要用于预测房屋建筑的抗震能力。利用NSPs,地震需求谱可以从特定地点的危险性谱中直接计算出来,而非线性时程分析需要全部地面运动和针对地震记录可变性的相关性评估。除此之外,基于恒载模式(ATC-40和FEMA-356中所推荐的)NSP简化版本有条文说明其无法考虑由结构弹塑性而导致的更高模态效应以及模态变化。因此,研究者纷纷提出解决了以上缺点的改进Pushover法。通过对典型的钢结构和钢筋混凝土结构的突出反应特征与一套全面的NTH分析中得到的基准反应的比较,研究了多种非线性静力分析方法(NSPs)的有效性。更重要的是,考虑到多种地面运动特征,还采用了一组从普通的远断层记录到近断层地面运动的时间序列。这项分析研究的结果显示,较之该项研究中的其他非线性分析方法,适应性组合模型方法可以更为准确地预测如层间位移、塑性角等的极值。
An essential and critical component of evolving performance-based design methodologies is the accurate es- timation of seismic demand parameters. Nonlinear static procedures (NSPs) are now widely used in engineering prac- tice to predict seismic demands in building structures. While seismic demands using NSPs can be computed directly from a site-specific hazard spectrum, nonlinear time-history(NTH) analyses require an ensemble of ground motions and an associated probabilistic assessment to account for aleato- ric variability in earthquake recordings. Despite this advan- tage, simplified versions of NSP based on invariant load pat- terns such as those recommended in ATC-40 and FEMA- 356 have well-documented limitations in terms of their ina- bility to account for higher mode effects and the modal vari- ations resulting from inelastic behavior. Consequently, a number of enhanced pushover procedures that overcome many of these drawbacks have also been proposed. This pa- per investigates the effectiveness of several NSPs in predic- ting the salient response characteristics of typical steel and reinforced concrete (RC) buildings through comparison with benchmark responses obtained from a comprehensive set of NTH analyses. More importantly, to consider diverse ground motion characteristics, an array of time-series from ordinary far-fault records to near-fault motions having fling and forward directivity effects was employed. Results from the analytical study indicate that the Adaptive Modal Combi- nation procedure predicted peak response measures such as inter-story drift and component plastic rotations more con- sistently than the other NSPs investigated in the study.
An essential and critical component of evolving performance-based design methodologies is the accurate es- timation of seismic demand parameters. Nonlinear static procedures (NSPs) are now widely used in engineering prac- tice to predict seismic demands in building structures. While seismic demands using NSPs can be computed directly from a site-specific hazard spectrum, nonlinear time-history(NTH) analyses require an ensemble of ground motions and an associated probabilistic assessment to account for aleato- ric variability in earthquake recordings. Despite this advan- tage, simplified versions of NSP based on invariant load pat- terns such as those recommended in ATC-40 and FEMA- 356 have well-documented limitations in terms of their ina- bility to account for higher mode effects and the modal vari- ations resulting from inelastic behavior. Consequently, a number of enhanced pushover procedures that overcome many of these drawbacks have also been proposed. This pa- per investigates the effectiveness of several NSPs in predic- ting the salient response characteristics of typical steel and reinforced concrete (RC) buildings through comparison with benchmark responses obtained from a comprehensive set of NTH analyses. More importantly, to consider diverse ground motion characteristics, an array of time-series from ordinary far-fault records to near-fault motions having fling and forward directivity effects was employed. Results from the analytical study indicate that the Adaptive Modal Combi- nation procedure predicted peak response measures such as inter-story drift and component plastic rotations more con- sistently than the other NSPs investigated in the study.
引文
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