Fuzzy logic controller for real-time substructuring applications

Real-time substructuring is a hybrid technique in which the critical component of the structure is tested, while the remainder is numerically analyzed based on a suitable model. The synchronization between the testing and the analysis is maintained by a controller. This paper proposes a new controller based on fuzzy logic for real-time substructuring applications. The advantage of a fuzzy-logic-based controller is that it is rule based and involves far less computations. The performance of the proposed controller is verified through numerical simulations of a substructured linear and nonlinear single-degree-of-freedom system for two different damping ratios. The performance of the controller is compared with that of conventional controllers which are used in real-time substructuring on the basis of a nondimensional error index. The fuzzy logic controller is found to have the least error index for the chosen nonlinear system and performs satisfactorily for a linear system. Furthermore, the effectiveness of the proposed fuzzy logic controller is demonstrated by numerically evaluating the response of a portal frame pinned at one of the beam column joints for the El-Centro earthquake. The displacement time history response was found to closely match that of the emulated system.