Grant: Research Tools and Instruments - Category 1 (<$150,000)

Experimental testing is essential for understanding the behavior of structures under extreme loading conditions which leads to the design and construction of safer structures. For example, by introducing properly designed supplemental damping devices (e.g., elastomeric and magnetorheological dampers), it is possible to mitigate the damage to the structural and nonstructural elements during a seismic event. 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. Real-time PSD and hybrid PSD testing methods can be employed for this purpose, 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 real-time test results. These challenges require a substantial program of dedicated research with an appropriate set of equipments. The applicant has the necessary background and experience to conduct further investigations in this area, and the requested equipment for real-time hybrid PSD testing system is flexible and cost-effective. By enabling the applicant's group to conduct coordinated analytical and experimental research, where the observations and results from one will be immediately used to modify (if necessary) the focus of the other, the requested equipment will expedite the progress on the way to enhance the real-time testing methods. By presenting the structural engineers with experimentally validated, enhanced testing methodologies, the proposed program aims to contribute to the design and understanding of next generation structures.