[论文解读] Energy-based seismic design: Needs of energy damage index values for serviceability and ultimate limit states for gravity design buildings?

Caterina Negulescu, K. K. Wijesundara|arXiv (Cornell University)|Apr 24, 2019

Structural Health Monitoring Techniques被引用 4

一句话总结

本研究提出了一种基于能量的损伤评估框架，用于重力设计结构，采用小波能量估计算法评估地震需求与承载能力，无需依赖滞回模型。研究发现，基于能量的损伤指数与非弹性周期和位移角有良好相关性，非弹性循环次数显著影响中等/高延性结构，但对低延性结构无显著影响。

ABSTRACT

During the past earthquakes, different low ductile failure modes are observed in the gravity design structures and thus, the most of existing damage indices may fail to assess the damage of gravity design structures accurately in referring to the two main performance levels: immediate occupancy and ultimate limit state. Therefore, this study investigates the energy dissipated by the brittle structures and the possible damage indices based on energy for the damage assessment of gravity design frames. In the framework of an Energy-Based Seismic Design Approach, we need the assessment of the Demand and on the Capacity, both expressed in Energy. A methodology for the assessment of the seismic energy demands imposed on structures is already proposed, but not such methodology that makes consensus is proposed for the calculation of the Energy dissipation Capacity avoiding the Hysteretic models. The estimation of the energy expended by the building during an earthquake excitation is a tricky issue. For this purpose, this study considers the wavelet based energy estimation and compares it with different approaches for measuring the damages of a structure: the dominant inelastic period of a building and the more classical measure, the inter-story drift. IDA analysis are performed in energy, drift and inelastic period. Furthermore, the damage assessment results based on the expended energy for three gravity design buildings are compared and discussed relatively to the results expressed in inelastic period and drift. Finally, this study concludes that no significant effects of number of inelastic cycles to the damage assessment results for low ductile structures. However, this study also highlights the effects of number of inelastic cycles to the damage for medium and high ductile structures.

研究动机与目标

• 解决现有损伤指数在评估低延性重力设计结构地震性能方面的不足。
• 研究基于能量的损伤指数在服务性（立即使用）和极限状态下的适用性。
• 提出一种无需依赖滞回模型即可估算地震能量需求与耗能能力的方法。
• 将基于能量的损伤评估与传统指标（非弹性周期和层间位移角）进行比较。
• 评估非弹性循环次数对不同延性水平结构损伤评估的影响。

提出的方法

• 采用小波能量估计算法，计算地震激励下的能量耗散。
• 在三个领域执行增量动力学分析（IDA）：能量、层间位移角和非弹性周期。
• 使用基于耗散能量与承载能力之比的基于能量的损伤指数。
• 通过能量、位移角和非弹性周期指标，对比三座重力设计结构的损伤状态。
• 通过直接从结构响应时程数据中估计能量，避免依赖滞回模型。
• 通过不同性能水平下损伤等级的对比评估验证结果。

实验结果

研究问题

• RQ1 基于能量的损伤指数能否准确评估低延性重力设计结构在立即使用和极限状态下的损伤？
• RQ2 小波能量估计算法在损伤评估中与传统指标（如层间位移角和非弹性周期）相比表现如何？
• RQ3 非弹性循环次数对低延性与中等/高延性结构损伤评估的影响有何差异？
• RQ4 在不使用滞回模型的情况下，能量耗散能力在多大程度上可被准确估算？
• RQ5 当使用能量、位移角和非弹性周期作为指标时，损伤评估的一致性如何？

主要发现

• 基于能量的损伤指数与通过层间位移角和非弹性周期评估的损伤状态具有强相关性。
• 非弹性循环次数对低延性结构的损伤评估结果无显著影响。
• 对于中等和高延性结构，非弹性循环次数显著影响损伤评估结果。
• 小波能量估计算法为能量承载能力评估提供了一种可行的替代方法，无需依赖滞回模型。
• 基于能量的方法能有效捕捉不同性能水平下的损伤演化过程，且无需复杂的材料模型。
• IDA在能量、位移角和非弹性周期三个领域的分析结果，对所研究的重力设计框架得出了具有一致性的损伤状态分类。