Smart Damping Strategies for Seismic Protection of Urban Structures

这项研究的目的是为在高度城市化地区减轻地震灾害的创新智能结构概念奠定广泛和完整的基础。研究计划分为两个相辅相成的工作：低/中高层建筑和桥梁，以及中/高层建筑。对于低/中层建筑和桥梁，将研究一种自适应基础隔震系统，该系统能够适应与近断层地震相关的高速、长周期地震事件产生的严重地面运动。提出的自适应隔振系统由低阻尼隔振轴承和使用磁流变(MR)流体的智能阻尼器组成，可以有效地适应不可预测的激励水平和类型。采用隔震支座和磁流变阻尼器的建筑结构克服了许多费用和技术困难，无法大规模实现可控隔震系统。对于中高层建筑，将研究智能阻尼器互联建筑。混合质量驱动器对于减小结构在大地震和风激励下的响应具有很高的潜力，它的另一种替代方法是使用一类主动控制系统，在具有不同动力特性的相邻建筑之间放置控制执行器。然而，对可靠性、外部电力、资本成本和维护的担忧依然存在。智能阻尼器，如磁流变阻尼器，已被证明具有主动控制方法的适应性，同时保持与被动阻尼器相似的可靠性。开发适用于这一应用的MR阻尼器具有很大的前景。该项目将专注于理解并将这两个互补的智能结构概念整合到保护土木结构免受近断层地震影响的可行方法中。这项研究将涉及：(1)智能基础隔震概念，(2)智能互联建筑概念，以及(3)能够利用自适应系统在减轻城市地震中的独特功能的控制策略。几种结构系统配置的概念验证实验将在圣母大学进行，并将开发出200 kip的原型阻尼器。该项目获得了美国国家科学基金会98-36“美日城市地震减灾合作研究”的资助。

This investigation is aimed to develop a broad and integrated foundation for innovative smart structures concepts for earthquake hazard mitigation in heavily urbanized regions. The research plan is divided into two complementary efforts: low/medium-rise buildings and bridges, and medium/high-rise buildings. For low/medium-rise buildings and bridges, an adaptive base-isolation system will be studies that are able to accommodate the severe ground motion generated by high-velocity, long-period, seismic events associated with near-fault earthquakes. The proposed adaptive isolation system is comprised of low-damping isolation bearings used in conjunction with smart dampers employing magnetorheological (MR) fluid and can effectively adapt to unpredictable excitation levels and types. The proposed architecture employing isolation bearings and the MR damper overcomes many expenses and technical difficulties, which preclude the broad-scaled realization of controllable isolation system.For medium/high-rise buildings, smart dampers interconnecting buildings will be investigated. An alternative approach to the popular method of hybrid mass driver, which has high potential for reducing structural responses due to large earthquake and wind excitations is to use a class of active control systems that places control actuators between adjacent buildings with different dynamic characteristics. Yet, concerns over reliability, external power, capital cost and maintenance remain. Smart dampers such as the MR damper have been shown to possess the adaptability of the active control approach while maintaining reliabilities familiar in passive dampers. Development of appropriate MR dampers for this application shows great promise.This project will focus on understanding and integrating the two complementary smart structures concepts into viable means for protecting civil structures against near-fault earthquakes. The research will involve development of: (1) smart base isolation concepts, (2) smart interconnected buildings concepts, and (3) control strategies that can exploit the unique features of the adaptive system in mitigating urban earthquakes. Proof of concept experiments for several structural system configurations will be carried out at the University of Notre Dame, and a 200 kip prototype damper will be developed. This project is awarded under NSF 98-36 "US-Japan Cooperative Research in Urban Earthquake Disaster Mitigation.