Abstract
A procedure for generating two-dimensional heterogeneous meso-scale concrete samples is developed, in which the multi-phasic features including the shape, size, volume fraction and spatial distribution of aggregates and pores are randomised. Zero-thickness cohesive interface elements with softening traction–separation relations are pre-inserted within solid element meshes to simulate complex crack initiation and propagation. Extensive Monte Carlo simulations (MCS) of uniaxial tension tests were carried out to investigate the effects of key multi-phasic features on the fracture patterns and load-carrying capacities. It is found that the fracture behaviour and stress-displacement responses of the numerical specimens are highly dependent on the random mesostructures, especially the post-peak softening responses. The specimens fail with either one or two macro-cracks, regardless of the shapes and volume fractions of aggregates and pores. Assuming that the aggregate–mortar interface is weaker than the mortar, using polygonal rather than circular or elliptical aggregates, or increasing the aggregate volume fraction will reduce the tensile strength of specimens. The porosity is found to have severely adverse effects on the specimen strength and cannot be neglected in mesoscale fracture modelling of concrete.
Highlights
Concrete is a composite material with multiple phases including mortar, aggregates, interfaces and various defects such as pores and weak inclusions
This paper presents a systematic study of statistical effects of key multi-phasic parameters on the complex fracture behaviour and load-carrying capacities of concrete specimens, through extensive Monte Carlo simulations (MCS) of direct meso-scale finite element models
Numerical models of concrete with random mesostructures comprising circular, elliptical, or polygonal aggregates and circular or elliptical pores have been developed in this study
Summary
Concrete is a composite material with multiple phases including mortar, aggregates, interfaces and various defects such as pores and weak inclusions. The direct algorithms can take into account key multi-phasic parameters such as the shape, size, gradation and spatial distribution of pores and aggregates, phase volume fractions and aggregate– mortar interfaces, and their effects on mechanical behaviour of specimens. This makes the direct algorithms attractive in mesoscale modelling, especially when accurate understanding of detailed failure mechanisms is required. This paper presents a systematic study of statistical effects of key multi-phasic parameters on the complex fracture behaviour and load-carrying capacities of concrete specimens, through extensive Monte Carlo simulations (MCS) of direct meso-scale finite element models. The MCS results are critically analysed, leading to valuable statistical results that may help improve designs of concrete material and structures
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