Refined Simulation of Cracked Reinforced Concrete Beams Based on Enhanced Bond-Based Peridynamics

Abstract

Peridynamics (PD) has been widely used in simulating the crack behaviors of brittle material due to its extraordinary capacity in analyzing deformations with discontinuities. In this paper, an enhanced bond-based peridynamics (BPD) model is proposed to study the crack behaviors of reinforced concrete (RC) beams. A modified nonlinear concrete bond model is presented to simulate the tensile-compressive softening and improve the model’s convergence. A novel steel bond model is developed considering the nonlinear behaviors in both axial and shear directions. A coupled axial–shear interaction (ASI) model is adopted to simulate the bond-slip behaviors between concrete and steel. Furthermore, reformulated BPD equilibrium equations are modified for implicit static analyses. A gradually weakening fictitious element (GWFE) approach is presented to improve the stability in implicitly solving the BPD equations. The algorithms are implemented in an open-source finite element (FE) software, OpenSees, for BPD analysis. Experiments are conducted for three RC beams with different shear span to depth ratios under concentrated vertical loads to verify the enhanced BPD model. The comparative studies are performed between experimental and simulated results, and nonlinear responses of RC beam are investigated, e.g. the responses of deflection-shear force, strain distribution on stirrups, the shear resistance, and the propagation of cracks. The results show that as the shear span-to-effective depth ratio increases, the capacity provided by RC beam decreases while stirrups gradually provide more capacity instead. It is also found that the yield deflection increases significantly with the growing shear span-to-effective depth ratio.