Modeling of anchor bolt pullout in concrete based on a heterogeneous assumption

In this study, numerical simulation of anchor bolt pullout in plain concrete by a heterogeneous numerical model is presented. The heterogeneity of the concrete material was modeled by randomly assigning strength and elastic modulus to the elements according to Weibull's distribution. The ongoing debonding process was obtained, including crack initiation, crack propagation and formation of the concrete cone. The numerical results indicate that there is a strong size effect on failure resistance of the concrete cone. By increasing the anchor head size, peak pullout load and the volume of concrete cone increase. The peak pullout load and the volume of concrete cone also increase with the increasing of embedded length. With this heterogeneous numerical model, the asymmetrical crack patterns and the crack branching observed in tests is obtained. Moreover, asymmetrical crack and crack branching were easy to occur with lower homogeneity index. The numerical results agreed well with the experimental investigations.

Research highlights
► The heterogeneity of the concrete material was modeled.
► The ongoing cracking process and formation of the concrete cone was obtained.
► The asymmetrical crack patterns and the crack branching observed in tests was obtained.