Real-time substructure testing of nonlinear structures with equivalent force control method

The equivalent force control method (EFC) replaces numerical iteration with feedback control strategy to solve the nonlinear equations of motion for real-time substructure testing with implicit integration method. For nonlinear structural tests, the EFC method with proportional-derivative (PD) controller will induce control errors in the equivalent force response and lead to inaccurate results. This paper chooses the proportional-integral (PI) controller, instead of the PD controller previously used, to eliminate the errors. The EFC method for real-time substructure test was introduced in this paper firstly, then the equivalent force controller was designed, and the effectiveness of the EFC method with PI controller for real time-substructure tests of nonlinear structures was verified with numerical simulations and actual tests. The numerical and experimental results have shown that the EFC method with a PI controller is very effective for nonlinear structural tests.