On July 27th and August 3rd, OpenFresco (the middleware software commonly used for local and distributed hybrid simulations) was used to conduct continuous geographically distributed hybrid simulations between the NEES facility at UC Berkeley (nees@berkeley) in the United States and the civil engineering laboratory at the University of Kassel (UNIKA) in Germany.
The experimental substructure of the test consisted of a friction device, named UHYDE-fbr, developed by Professor Uwe Dorka of UNIKA (mainly utilized for providing energy dissipation in bridge type structures), and a fixed tuned-mass-damper. The computational portion of the hybrid model consisted of a single degree of freedom mass with viscous damping. Dr. Andreas Schellenberg and Dr. Selim Gunay executed computations at UC Berkeley (shown in image above), and the experimental substructure was located at the University of Kassel.
The communication between the computational platform and the test structure was made possible by using OpenFresco. Based on preliminary tests, the average network communication time was determined to be around 0.2 seconds. Given the uncertainty in network communication speeds, the simulation time step was set at 1 second. The integration time step was 0.01 seconds, resulting in a test 100 times slower than real time; however, with the use of Dorka's substructure algorithm, the actuators never stopped moving. This, therefore, resulted in a successful continuous intercontinental geographically distributed test.
Congratulations to the research team for such an extraordinary demonstration of the benefits of combining hybrid simulation, OpenFresco and international collaboration!
For more information about this test, visit the OpenFresco website.