CAREER: Advanced Acceleration Control Methods and Substructure Techniques for Shaking Table Tests

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The research objective of this Faculty Early Career Development (CAREER) program project is to develop methodologies that enhance accuracy and capabilities of shake table testing of structures. In particular, this study aims to improve acceleration control methods to reproduce reference accelerations at shake table and to develop substructure techniques to account for dynamically varying boundary conditions. The accurate reproduction of reference accelerations is critical for the investigation of their true impact on structures. By combining feed-forward and feedback control, innovative, high-performance acceleration control methods will be developed through analytical and computational studies. These acceleration control methods will be experimentally validated based on multiple stability and performance criteria under various conditions. Special attention will be paid to acceleration trajectory tracking performance. When partial structural models are tested on a shake table, substructure techniques that take into account interactions with boundary members are essential for the systems level assessment. Substructure techniques for shake tables will be explored using two approaches: 1) inertial force approach, where the acceleration of a supplemental inertial mass is controlled to generate an inertial force that is equivalent to the boundary force, and 2) direct force approach, where the dynamic boundary force is directly imposed by dynamic actuators. Numerical integration algorithms that are required for the substructure techniques will also be developed. Capabilities and limitations of the substructure shake table tests will be investigated through numerical and experimental studies. The results of this research will have a direct impact on earthquake engineering, by providing accurate experimental means for seismic performance assessment of structures under dynamic loadings and boundary conditions. This research also meshes well with the scope of the National Science Foundation, George E. Brown Jr. Network for Earthquake Engineering Simulation program. The project will provide integrated education and research opportunities for students at all-levels. In activities for K-12 students and the general public, the focus will be placed on linking their knowledge and the project through hands-on laboratory experience. Specific targets include high-school students in the Woman In Science and Engineering Program at the Johns Hopkins University and the Practicum Program at Baltimore Polytechnic High School. At the college level, this research will be integrated into a laboratory for the undergraduate Dynamics course that the PI is currently offering. It will also provide undergraduate research opportunities that help students develop fundamental understanding of theories in dynamics and control. At the graduate level, a new course, "Advanced Experimental Methods for Structures", will integrate the project into the course lecture and laboratory activities. This research will be disseminated through the project website, and the results will be published through a number of significant journals and conference proceedings.