A Simple Hybrid Testing Approach For Dynamic Analysis of Civil Structural Control Devices

Effective real-time testing of structural control devices relies on a hybrid test system that couples virtual structures under dynamic loading with physical sub-structures or devices in a dynamic test rig. The use of sensors and actuators in a closed-loop feedback system maintains the dynamic equilibrium of the overall system comprising the physical test article and virtual modelled structure. The virtual-real hybrid testing method thus alleviates much of the time and cost associated with full-scale testing and enables tests that would be infeasible without full-scale complete structural tests. Thus, it can reduce the uncertainty in designing such a full scale test by testing, in hybrid hardware in the loop fashion, the devices and subsystems required to ensure the best overall full-scale experimental design. Hence, a major outcome is the savings in the cost, time and complexity of the resulting full scale experiment. To accomplish this goal, this research presents simple, cost-effective and robust hybrid test system, and outlines solutions to the major issues faced in developing any hybrid system. The overall approach is centred on the dSpace TM real-time control system development tool. The major issues in developing a hybrid system are: minimal signal processing lag, optimised sensing resolution and bandwidth, and efficient model computation. All three affect the ability of the system to maintain dynamic equilibrium of the overall virtual-physical system, and thus provide an accurate test. The final system readily accommodates non-linear-single and multi-degree-of-freedom models and an operating bandwidth of 1 kHz. Test results and experimental outcomes are based on studies of a linear single degree of freedom structure and a non-linear rocking wall system that includes impact loads and timing subject to random ground motions. The results clearly illustrate system simplicity, efficacy and how they can be used to illustrate the potential outcomes of full scale experiments but at simple, fast low cost level.