NEESR-SG: Development of Next Generation Adaptive Seismic Protection Systems

该奖项是NSF 08-519项目招标的结果，乔治·e·布朗地震工程模拟（NEES）研究网络（NEESR）竞赛包括莱斯大学作为牵头机构，布法罗大学、伦斯勒理工学院、加州大学洛杉矶分校和加州州立大学弗雷斯诺分校都获得了次级奖项。传统设计的结构框架系统在强震作用下会产生显著的非弹性变形，导致非弹性滞后行为、刚度和强度退化、层间漂移增加和残余漂移损伤。附加阻尼装置形式的被动地震防护系统已经成为通过将非弹性能量耗散从框架系统转移到阻尼器来减少响应和限制损伤的有效方法。然而，这种阻尼器通常不提供自定心刚度能力或反刚度退化。最近的研究表明，自适应刚度和阻尼（ASD）装置的组合可以提供实质性的响应修正，特别是在近断层脉冲型地震中。ASD设备通过优化改变与振动频率和耗散力（阻尼）相关的恢复力（刚度）来提供结构响应修改能力，耗散力（阻尼）控制结构动力系统的行为。迄今为止，与补充阻尼系统相比，自适应刚度系统受到的关注相对较少，因此在地震工程中存在重大差距。因此，有必要开发新的ASD装置，将结构系统的耗能和相关刚度变化转移到ASD装置上，以减少框架内的损伤，消除残余的层间漂移，并提供自定心能力。本项目的研究愿景是将新型的自定心自适应刚度体系与高效耗能相结合，开发下一代抗震防护体系。目标是通过开发带有反馈的独立半主动ASD设备和带有内部液压反馈的被动ASD设备来模拟主动控制设备的行为。核心策略包括对潜在的主动、半主动和被动系统进行全面的分析和实验研究，然后综合和开发实用的可调节被动系统和自包含半主动系统，以便在实际结构中实施。这种方法与国防工业采用的方法是一致的，并有望导致ASD系统在民用结构中的广泛应用。该项目预计将通过调整结构响应来提高抗灾能力，有助于减轻地震危害和震后恢复（由于易于更换ASD系统）。该项目将通过教育外展和通过项目网站广泛传播研究成果，对地震工程实践产生广泛影响。此外，该项目将通过西班牙裔服务机构的积极参与，对代表性不足的群体的学生产生重大影响。该项目将利用NEES设备现场和布法罗大学的实验设施来实现其目标。实验结束后，该项目的所有数据将通过NEES数据存储库（http://www.nees.org）提供。

This award is an outcome of the NSF 08-519 program solicitation George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR) competition and includes Rice University as the lead institution with subawards to the University at Buffalo, Rensselaer Polytechnic Institute, University of California-Los Angeles, and California State University-Fresno. Conventionally designed structural frame systems develop significant inelastic deformations under strong earthquakes, leading to inelastic hysteretic behavior, stiffness and strength degradation, increased interstory drifts, and damage with residual drift. Passive seismic protection systems in the form of supplemental damping devices have emerged as an effective approach for reducing response and limiting damage by shifting the inelastic energy dissipation from the framing system to the dampers. However, such dampers do not generally provide self-centering stiffness capability or counter stiffness degradation. Recent investigations have shown that a combination of adaptive stiffness and damping (ASD) devices can provide substantial response modification, particularly during near-fault pulse-type earthquakes. ASD devices offer structural response modification capability by optimally varying the restoring forces (stiffness) linked to the frequencies of vibration and dissipative forces (damping) that govern the behavior of a structural dynamic system. To date, adaptive stiffness systems have received relatively little attention as compared to supplemental damping systems and thus represent a significant gap in earthquake engineering. Hence, development of new ASD devices is necessary to shift the energy dissipation and associated stiffness variations from the structural system to the ASD devices to reduce damage in frames, eliminate residual interstory drift, and provide self-centering capability. The research vision of this project is to develop the next generation of seismic protection systems by combining a new class of self-centering adaptive stiffness systems with highly efficient energy dissipation. The goal is to mimic the behavior of actively controlled devices by developing self-contained semi-active ASD devices with feedback and passive ASD devices with internal hydraulic feedback. The core strategy involves a comprehensive analytical and experimental investigation of potential active, semiactive, and passive systems followed by the synthesis and development of practical adjustable passive systems and self-contained semi-active systems for implementation in practical structures. Such an approach is consistent with that adopted in the defense industry and is expected to result in widespread application of ASD systems in civil structures. The project is expected to advance the state-of-the-art of increased resilience through structural response modification, contributing to earthquake hazard mitigation and expedient post earthquake recovery (due to easy replacement of ASD systems). The project will broadly impact earthquake engineering practice through educational outreach and wide dissemination of research findings through the project web site. Additionally, the project will have a significant impact on students from underrepresented groups through active involvement of a Hispanic Serving Institution. This project will utilize the NEES equipment site and experimental facilities at the University at Buffalo to achieve its goals. Following the experiments, all data from this project will be made available through the NEES data repository (http://www.nees.org).