Hysteretic energy-based state-dependent fragility for ground-motion sequences

Gentile Roberto; Galasso Carmine

摘要

A framework to derive state-dependent fragility relationships of structures subjected to ground-motion sequences (e.g. mainshock-aftershock (MS-AS) or triggered earthquakes) is proposed. The hysteretic energy dissipated in the sequence is adopted as the main demand parameter, as it is a cumulative measure monotonically increasing with the length of the excitation. For a structure subjected to earthquake-induced ground motions, it is not possible to define a closed-form representation of the hysteretic energy as a function of the peak deformation. However, based on theoretical considerations, the hysteretic energy-peak deformation trend is discussed, highlighting that (a) the significant duration of the ground motion explains the variability of the hysteretic energy for a given peak deformation; (b) the hysteretic energy dissipated in an AS decreases (for a given AS peak displacement) if the peak displacement in the MS increases. A vector-valued probabilistic seismic demand model consistent with these considerations is proposed in the form of a surface relating the hysteretic energy in the sequence to the peak deformation in the MS and a ground-motion intensity measure of the AS. This is calibrated via sequential cloud-based time-history analyses. The framework is demonstrated for 14 reinforced concrete frame buildings with different height, plastic mechanisms, and infill distributions. The results show the feasibility of the proposed approach, effectively capturing damage accumulation without inconsistencies in the obtained statistical model. The framework may be used for risk-assessment applications explicitly incorporating ground-motion sequences. The hysteretic energy versus peak deformation relationship may also be exploited in problems involving long-duration ground motions or soft soils.

机译：提出了一种衍生经受地面运动序列的结构的状态依赖性脆弱关系的框架（例如，主轴 - 余震（MS-AS）或触发地震）。采用序列中渗透的滞后能量作为主要需求参数，因为它是累积措施，随着激励的长度而单调地增加。对于受地震诱导的地面运动的结构，由于峰值变形的函数，不可能限定滞后能量的闭合形式表示。然而，基于理论考虑，讨论了滞后能量峰值变形趋势，突出显示（a）地面运动的显着持续时间解释了给定峰值变形的滞后能量的可变性; （b）如果MS中的峰位增加，则在AS中散发的滞后能量（对于作为峰位移）的降低（给定为峰位移）。载有与这些考虑因素一致的矢量值概率地震需求模型，以序列中的滞后能量与MS中的峰值变形相关的表面和作为作为的地面运动强度测量的表面。这通过顺序云的时间历史分析进行校准。该框架是针对具有不同高度，塑料机制和填充分布的14个钢筋混凝土框架建筑物。结果表明，所提出的方法的可行性，有效地捕获损伤积累而没有所获得的统计模型不一致。该框架可用于明确地结合地运动序列的风险评估应用。滞后能量与峰值变形关系也可以在涉及长期接地运动或软土壤的问题中被利用。

Hysteretic energy-based state-dependent fragility for ground-motion sequences

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