Implementation Issues of Structural Control for Near Field Earthquakes: Hardware Malfunction and Saturation

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9615731 Jabbari This project will address critical implementation issues associated with active control for urban seismic hazard mitigation, particularly excitations due to near-field earthquakes. These issues include hardware malfunction and actuator saturation, which arise in the performance-based design of control systems. The recent near-field earthquakes of Northridge and Kobe have raised great concerns regarding the applications of both passive base isolation systems (such as rubber-bearing isolators) and active/hybrid protective systems. The characteristics of near field earthquakes, including unexpected large peak ground acceleration and shock-type time histories, may render both passive isolation systems and active/hybrid protective systems ineffective or even detrimental. In the implementation of active control systems possible malfunction of hardware, such as actuators or sensors, may occur due to the infrequent use or due to shock-type excitations, such as that of near-field earthquakes. Due to the limited capacity of any actuator, as well as the random nature of earthquake excitations, the actuator may become saturated, particularly under the near-field earthquakes. Further the robust controller design for the reduction of peak structural response needs to be carefully addressed. This project will attempt to establish control design methods that guarantee high performance in the presence of potential hardware malfunction and actuator saturation. The performance obtained depends explicitly on the reliability (or malfunction) characteristics of hardware, actuator capabilities and the design earthquake. Consequently, the evaluation of costs and benefits for implementing an active control system becomes possible. Finally, a comprehensive experimental test program will be conducted suing the state-of- the-art shaking table at the University of California-Irvine to verify and demonstrate the effectiveness of the proposed techniques. A di stinguished feature of our technical approach is that all the issues to be addressed, including the malfunction of hardware systems, actuator saturation, peak response reduction and system robustness, can be formulated in a unified and comprehensive framework. The main thrust of the project can thus be summarized as developing a comprehensive control design methodology that will provide reliability with respect to actuator/sensor malfunction, high performance with actuator saturation, robustness and peak response reduction, and experimental verification and evaluation. ***