A meso-scale size effect study of concrete tensile strength considering parameters of random fields

Abstract

This study analyses size effects of concrete under uniaxial tension by Monte Carlo simulations, where heterogeneous strength at meso-scale is modelled by Weibull random fields with statistical parameters including correlation length and variance. For a given sample size and different random field parameters, a sufficient number of random field realisations are simulated to obtain statistical information from macroscopic stress-strain curves, while the complex meso-crack initiation and propagation is captured by the phase-field regularized cohesive zone model (PF-CZM). The effects of sample size and material heterogeneity on macroscopic tensile strength are analysed, and the quasi-brittle transition between plasticity and linear elastic fracture mechanics (LEFM) is well simulated using the nonlocal PF-CZM. It is also found that both the correlation length and the variance affect the trend of size effect in varying degrees: larger correlation length and higher variance with higher heterogeneity lead to more dispersed responses that approach the LEFM descending line. A modified law in three-dimensional parametric space is proposed by data regression for effective assessment of size effect and structural reliability.