Delay estimation and compensation in Real-time Hybrid Simulation with BRB specimen

Real-Time Hybrid Simulation (RTHS) is a novel approach conceived to evaluate dynamic responses of structures with parts of a structure physically tested and the remainder parts numerically modelled. One challenge of the method is to ensure real-time interaction of parts –substructures- via loading control, involving delay estimation, delay compensation and transfer system control. In RTHS, delay estimation is often a precondition of compensation; nonetheless, system delay may vary during testing. Consequently, it is sometimes necessary to measure delay online. Along these lines, we proposed an estimator with Taylor series based on a simplified physical system model, i.e. a pure delay multiplied by a gain reflecting amplitude errors of physical system control. The least-squares algorithm is introduced as well in order to render the estimator more practical yet effective.
In order to physically verify this method, Real-time Hybrid Simulation with a BRB specimen were carried out at the Mechanical and Structural Testing Center of the Harbin Institute of Technology and presented here. The emulated structure is a single degree of freedom structure. The specimen is a Buckling-Restrained Brace (BRB), which behaves linearly and nonlinearly in two tests, respectively.