Adaptive hysteretic model for reinforced concrete columns including variations in axial force and shear span length

Abstract

In this study, a hysteretic model is developed for simulating the nonlinear response of reinforced concrete columns with strength degradation behavior under cyclic loading. During analysis, the proposed model exhibits the ability to adjust the model parameters assigned to the model continually, based on the monitored element boundary conditions. A semi-empirical relationship between model parameters and boundary conditions is formulated from experimental evidence, which is used to adjust the model parameters. The boundary conditions that are monitored include the axial load acting on the column section and shear span length; these are known to have a significant effect on capacity in terms of strength and ductility. The developed model was implemented in the widely used research-oriented structural analysis software, OpenSees. To simulate the nonlinear response of the columns, model parameter predictive equations composed of input parameters such as material strength, reinforcement layout, and specimen geometry were developed using lasso regression. As an application of the proposed column model, an eight-story code-conforming frame building was selected to perform incremental dynamic analyses based on 44 far-field ground motions. The numerical results showed that, without the model parameter adaptation feature, the median collapse capacity and residual story drift can be significantly overestimated.