The Real-time Multi-directional (RTMD) Earthquake Simulation Testing Facility has recently been commissioned at the ATLSS Center. This facility has state-of-the-art servo-hydraulic equipment (servo-valves, accumulation and piping systems). The control system for this equipment is a digital system with a PID control law programmed on a DSP. A recent study at Lehigh University has established that PID control alone cannot be reliably used for real-time testing of structural components or systems. This is because the overshoot and steady state error in the target displacement of the actuator is too large and a latency in feedback command exists that does not enable accurate control of an actuator under high rates of loading resembling earthquakes.
A study is proposed to develop adaptive servo-hydraulic control and to implement it into the RTMD facility. These new control laws will be implemented for real-time hybrid simulation. The project will involve constructing a damper test bed, consisting of a rate-dependent damper attached to the laboratory floor and dynamically loaded in real-time using one of the NEES servo-hydraulic actuators. A reaction bracket will be utilized to attach the damper to the laboratory floor. An adaptive control law will be developed based on tracking error.
The project is to establish real-time testing capabilities with advanced servo-hydraulic control capabilities at the Lehigh University NEES Equipment Site for testing of structural systems with dampers. This includes a test bed (consisting of the damper test setup that is coupled to an analytical model of the remaining part of the structure) for conducting research and training, and training software for hydraulics-off mode.
The project will expand the capabilities of the ATLSS facility, and enable the laboratory staff to become well trained and experienced in large-scale fast testing. A graduate student will be supported by the project, who will become trained and experienced in conducting real-time testing. The results from the project will offer numerous additional benefits. The Lehigh NEES Equipment Site will be at the forefront in real-time structural testing by having advanced servo-hydraulic control capabilities to support its state-of-the-art equipment. The project will also extend the state-of-the-art in integrated experimental-analytical simulation in earthquake engineering.
James Ricles, Cheng Chen
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