Fracture Behaviour of Real Coarse Aggregate Distributed Concrete under Uniaxial Compressive Load Based on Cohesive Zone Model

Abstract

Two-dimensional meso-scale finite element models with real aggregates are developed using images obtained by digital image processing to simulate crack propagation processes in concrete under uniaxial compression loading. The finite element model is regarded as a three-phase composite material composed of aggregate, mortar matrix and interface transition zone (ITZ). Cohesive elements with traction–separation laws are used to simulate complex nonlinear fracture. During the experiment, digital image correlation (DIC) was used to obtain the deformation and cracks of the specimens at different loading stages. The concept of strain ratio is proposed to describe the effectiveness of simulation. Results show that the numerical strain ratio curve and stress–strain curves are both in good agreement with experimental data. The consistency between the cracks obtained by simulation and those obtained by DIC shows the good performance of cohesive elements as well as the effectiveness of simulation. In summary, the model is able to provide accurate predictions of the whole fracture process in concrete under uniaxial compression loading.

Numerical Method for Creep Analysis of Strengthened Fatigue-Damaged Concrete Beams

“…The stress-strain curve derived from the uniaxial compression test an the cracked concrete obtained from the tensile test were used to determine t age threshold (W), as presented in Table 4. The values of the other param listed in the table following the literature [27,40].…”

“…The stress-strain curve derived from the uniaxial compression test and the strain of the cracked concrete obtained from the tensile test were used to determine the initial damage threshold (W), as presented in Table 4. The values of the other parameters are also listed in the table following the literature [27,40]. The creep development curve of the uniaxial compression creep test of the concrete prism is shown in Figure 11.…”

Analytical Model with Independent Control of Load–Displacement Curve Branches for Brittle Material Strength Prediction Using Pre-Peak Test Loads

“…This study is based on the analysis of known data and synthesis using the ideas of mathematical modeling and fracture mechanics of brittle materials, reflected in the literature cited above [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The contributions of this study, taking into account the contents of Sections 1.1 and 1.2, as well as methodological aspects, include:…”

“…The analytical expression of this restriction can be obtained from equation d 2 σ/dε 2 = 0. Taking into account Function (8), it follows that coordinate ε of the inflection point of the left and right branches of the complete curve σ(ε) (7) is related to ε peak , respectively, by the relations:…”

“…Damage and fracture analysis has gradually become an independent branch of materials and structures mechanics [1][2][3]. Methods of fracture mechanics combined with numerical methods of computer modeling are implemented in software complexes, which are effective tools to analyze and predict the mechanical state of engineering structures and their fragments [4][5][6][7][8]. However, this is only one facet of the complex of actual problems of modeling and analyzing the behavior of materials in the brittle state.…”