Fiber-Based Nonlocal Formulation for Simulating Softening in Reinforced Concrete Beam-Columns

Abstract

A nonlocal formulation framework is presented to address mesh-dependent strain localization in displacement-based frame element models in the presence of constitutive softening. The framework consists of a nonlocal displacement-based frame element and a nonlocal fiber-based plasticity model, and is used to simulate the postpeak response of RC structural members. The algorithmic implementation of the framework is discussed, and its performance is thoroughly investigated. Mesh sensitivity studies reveal that the proposed approach eliminates mesh-dependent strain localization and leads to objective global (i.e., load displacement) and local (i.e., curvature profile) response in the presence of concrete softening. Comparison with historical test data from 24 column specimens shows that the postpeak response of RC beam-columns is predicted with reasonable accuracy. The limitations of the presented framework are discussed along with areas for further development.