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Operation and control of a seismic simulator

University of British Columbia

This dissertation deals with issues related to digitally controlled hydraulic shake tables with multi-axis degrees of motion. The recently upgraded table at the University of British Columbia was used for a variety of experiments, demonstrating a number of important issues associated with using a seismic simulator to conduct a test. Physical issues are associated with the stiffness and weight of the table, the force rating of the actuators and the capacity of the hydraulic power supply. Control issues are associated with the computer control algorithms, the configuration of analogue and digital controllers and the feedback system. As part of this study, a simplified simulation method was developed to determine the physical demands of a test sequence on a hydraulic system. The method can be efficiently applied to calculate the supply pressure drop, that results from the hydraulic actuator motions. An algorithm that removes undesirable effects of terminal velocity and displacement of a simulated earthquake of prescribed duration was introduced as part of this thesis. It proved to be a powerful tool for the preparation of earthquake time histories for simulation by a state-of-the- art controller. Post-compensation is used to limit the natural permanent drift and terminal velocity that occurs in recordings of earthquake motions. Results from a number of tests conducted at the University of British Columbia were used to demonstrate performance characteristics and limitations of shake table testing. A series of tests conducted on the table with rigidly attached weights helped calibrate the simulation model. The replication performance of the shake table was investigated with the results from test on the dynamic behaviour of telecommunication equipment racks. A 0.27 scale model of as-built bridge bent and a quarter-scale model of a steel plate shear wall building module were tested with the U.B.C. seismic simulator. These studies demonstrated the complexity of the control system and its interaction with the physical parameters of the shake table.

Thesis/Dissertation

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2009-07-03

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http://hdl.handle.net/2429/10140

Civil Engineering

University of British Columbia

UBCV

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