Developments for real-time pseudodynamic (PSD) and hybrid PSD test methods

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The potential for earthquakes to cause loss of life, structural damage and interruption of service is of great concern, and has gained increased awareness in the development of performance based design of structures. Numerous devices (e.g., elastomeric and magnetorheological dampers) have been recently developed as a means of reducing the seismic hazard in structures. To enable widespread use of these load-rate dependent devices, it is necessary to develop performance based design codes which require knowledge of structural performance from real-time tests of structures equipped with these devices. The real-time pseudodynamic (PSD) and hybrid PSD test methods offer ideal ways to address this need, where in the latter method only the critical components are physically tested and the remaining part of the structure is modeled in a computer. In real-time testing, the need to operate hydraulic actuators at fast rates inevitably brings along control issues; and unless the time delays (due to actuator response time, communication, computing time, etc.) are accurately compensated, accuracy and stability problems are likely to occur. The challenges include accurate control of multiple actuators that introduce variable time delay, representative modeling of the analytical substructure and its execution in real-time, and the lack of a standardized tool to establish the quality of the real-time test results. The proposed research program aims to gain an in-depth understanding necessary to handle the current challenges; to develop methodologies to overcome them; and thereby to enable a broader domain of application for these test methods. By presenting structural engineers with enhanced testing methodologies, the proposed program will contribute to the design and understanding of next generation structures.