Bouc–Wen class models considering hysteresis mechanism of RC columns in nonlinear dynamic analysis

Abstract

Bouc–Wen class models have been widely used to describe the hysteretic behaviors of structures in nonlinear dynamic and stochastic analyses. Since the existing Bouc–Wen class models cannot fully represent the hysteretic characteristics of reinforced concrete (RC) columns with structural degradation, the model fitted to the hysteresis loop from a specific input loading may not provide accurate response predictions under general loading conditions. To address this issue, we first identify two hysteresis mechanisms of RC columns, namely acute deterioration and pinching relaxation. Next, a new Bouc–Wen model is proposed to describe the hysteresis mechanisms based on the modified Bouc–Wen–Baber–Noori (m-BWBN) model. The proposed model considers the hysteresis mechanisms by two additional parameters, which are adequately bounded to facilitate the parameter identification process. Two different input loadings, i.e., a monotonically increasing one and the other with a sudden increase and decrease of the amplitude, are introduced to investigate the effects of the input loading patterns on the model calibration. The fitted models are applied to predict the responses under a quasi-static cyclic loading and a real earthquake ground motion. The effectiveness of the proposed model is demonstrated by comparison with nonlinear finite element analyses of RC columns in a database. While the m-BWBN and the proposed model show good agreements in the model calibration, only the proposed model calibrated by the input loading with sudden amplitude changes successfully predicts the responses of degrading RC columns. The proposed model will contribute to highly efficient and accurate predictions by nonlinear dynamic and stochastic analyses of a degrading structure modeled by an equivalent single-degree-of-freedom system.