Smart Damping Strategies for Seismic Protection of Urban Structures

本研究旨在为在高度城市化地区减轻地震危害的创新智能结构概念提供广泛而综合的基础。研究计划分为两个互补的努力：低/中层建筑和桥梁，和中/高层建筑。对于中低层建筑和桥梁，将研究一种自适应基础隔离系统，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剧烈地面运动。所提出的自适应隔离系统由低阻尼隔离轴承和采用磁流变（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。采用隔震轴承和磁流变阻尼器的结构克服了许多费用和技术困难，阻碍了可控隔震系统的大规模实现。对于中高层建筑，将研究智能阻尼器连接建筑物。普遍采用的混合质量驱动方法在减少大地震和风激励下的结构响应方面具有很大的潜力，另一种替代方法是使用一类主动控制系统，将控制执行器放置在具有不同动力特性的相邻建筑物之间。然而，对可靠性、外部电源、资本成本和维护的担忧仍然存在。智能阻尼器，如MR阻尼器已被证明具有主动控制方法的适应性，同时保持被动阻尼器所熟悉的可靠性。为这种应用开发合适的磁流变阻尼器显示出巨大的希望。该项目将侧重于理解和整合两种互补的智能结构概念，使其成为保护土木结构免受近断层地震影响的可行手段。该研究将涉及：(1)智能基础隔离概念，(2)智能互联建筑概念，以及(3)可以利用自适应系统的独特功能来减轻城市地震的控制策略。几个结构系统配置的概念验证实验将在圣母大学进行，并将开发一个200基普的原型阻尼器。本项目获国家自然科学基金98-36“美日城市地震减灾合作研究”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.