Fast hybrid simulation with geographically distributed substructures

The hybrid simulation test method is a versatile technique for evaluating the seismic performance of structures by seamlessly integrating both physical and numerical simulations of substructures into a single test model. Using hybrid testing, complex structural systems composed of multiple large-scale experimental and numerical substructures can be evaluated by linking experimental facilities using the internet. In this paper, a distributed control strategy is presented that supports the implementation of hybrid testing with geographically distributed substructures using advanced algorithms that offer improved accuracy. The objectives are to provide a scalable framework for multiple-substructure testing at distributed sites and to improve the reliability of the test results by minimizing strain-rate and force relaxation errors in the remote experimental substructures. The control strategy is based on a multi-threaded simulation coordinator combined with an event-driven controller at the remote experimental sites. The effectiveness of this procedure is demonstrated by computing the earthquake response of a six-span bridge model with five remote experimental and numerical column substructures distributed within laboratories across the U.S. Further, the distributed tests were implemented using a secure network link between the testing sites that was developed for the NEES cyber-infrastructure. Copyright ASCE 2006.