degrading Bouc-Wen model parametrers identification under cyclic load

The Bouc–Wen model of hysteresis is used in structural engineering to describe a wide range of nonlinear hysteretic systems, as consequence of its capability to produce a variety of hysteretic patterns. This research focuses on the application of the Bouc–Wen model to predict the hysteretic behaviour of reinforced concrete bridge piers. The purpose is to identify the optimal values of the parameters so that the output of the model matches as well as possible the experimental data. Two repaired and retrofitted reinforced concrete bridge pier specimens (in a 1:6 scale of a real bridge pier) tested physically in a laboratory are considered in this paper. An identification of Bouc–Wen model’s parameters is performed using the force–displacement experimental data obtained after cyclic loading tests on these two specimens. The original model involves many parameters and complex pinching and degrading functions and this makes the identification solution unmanageable and with numerical problems. Furthermore, from a computational point of view, the identification takes too much time. The novelty of this work is the proposal of a simplification of the model allowed by: simpler pinching and degrading functions; reduction of the number of parameters. The latter innovation is much effective in reducing computational efforts and is performed after a deep study of the mechanical effects of each parameter on the pier response. This simplified model is implemented in a MATLAB code and the numerical results are well fitting the experimental ones and are reliable in terms of manageability, stability, and computational time.