Numerical Study Of The Cracking Process Of Concrete Based On Mesoscopic Model

Concrete is a very complex material with a variety of inhomogeneities. Its overall mechanical prosperities depend on the material properties of different composites. Furthermore, the inside configuration of concrete has significant influence on the crack initiation and damage evolution. In this sense, a mesoscale model which treats concrete as a heterogeneous material provides a powerful approach to study concrete deeply. This paper aims to develop a numerical modelling strategy for simulating cracking of concrete, with focus on its heterogeneous material configuration and quasi-brittle mechanical behaviours.On mesoscale concrete is regarded as a kind of three-phase material composed by aggregates, cement mortar and interfacial transition zones (ITZ). In this paper, the mesoscopic internal structure of concrete is represented as a particles structure with polygonal or polyhedral aggregates embodied in homogenous mortar matrix.A so called mesoscopic cohesive model is developed in the present paper. The numerical model is established by inserting cohesive elements into a regular finite element mesh aligned with the phases boundary. A nonlinear traction-separation constitutive law is employed for cohesive elements to describe the cracking behaviour of the material. In order to avoid the divergence problem, an explicit dynamics solution algorithm available in ABAQUS/Explicit is adopted to solve the extremely nonlinear problem.Using the present model, a cubic specimen under three load cases, uniaxial tension, splitting and uniaxial compression is analyzed. Rather realistic mechanical responses and cracking evolution processes, as well as fracture and crash patterns are acquired. Additional study is carried out to find how the load velocity, aggregate volume and random mechanical parameters influence the computation result for uniaxial tension numerical test, and how the aggregate dimension influence the size of fracture process zone. Finally the model is extended to 3-D condition, and a uniaxial tension numerical test is carried out. Similar fracture pattern but higher tensile strength is acquired.