Performance of Equivalent Force Control Method for Real-Time Substructure Testing

Abstract eng:
The equivalent force control (EFC) method has been developed for real-time substructure testing (RSTing) with implicit integration to replace the numerical iterative process with a feedback control. This paper addresses two issues concerning the performance of this method. One is the determination of the force-displacement conversion factor (a key component of EFC) for nonlinear specimens. The analysis conducted here shows that the force-displacement conversion factor is largely governed by the mass and damping properties of the numerical substructure and the properties of the numerical scheme when a small integration time interval is used. Otherwise, the factor has to be determined with the secant stiffness of the specimen and of the numerical substructure if a PD controller is used for EFC. The other issue is the overshooting problem which may arise for multi-degree-of-freedom structures due to the relatively quick response feedback from the numerical substructure in the closed-loop EFC. It is shown that this problem can be resolved by reducing either the EFC gains or the increment size of the equivalent force command. The analytical studies on these two issues are verified by RSTs conducted on structural models with buckling restrained braces and an offshore platform with Magnetorheological dampers.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket