Experimental verification of an accessible geographically distributed real-time hybrid simulation platform

Real-time hybrid simulation (RTHS) has become a recognized methodology for isolating and testing complex, rate-dependent structural components and devices to understand their behavior and to evaluate their ability to improve the performance of structures exposed to severe dynamic loading. Although RTHS is efficient in its utilization of equipment and space compared with conventional testing techniques, the laboratory resources may not always be available in a single testing facility to conduct large-scale experiments. Consequently, distributed systems, capable of connecting multiple RTHS setups located at several geographically distributed facilities through appropriate information exchange, become desirable. This study presents a distributed RTHS (dRTHS) platform that enables the integration of geographically distributed physical and numerical components across the Internet. The essential capabilities needed to establish such a dRTHS platform are discussed, including the communication architecture, network components, and connection reliability. One significant challenge for conducting successful dRTHS is sustaining real-time communication between test sites. To accommodate realistic network delays due to variations in the Internet service, a Smith predictor-based delay compensation algorithm that includes a network time delay estimator is developed. A series of numerical and experimental studies is conducted to verify the platform and to quantify the impact of uncertainties present in a typical distributed system. Through an evaluation of the results, it is demonstrated that dRTHS is feasible for coupling laboratory capabilities and is a viable alternative to traditional testing techniques.