Dynamic Fracture Of Concrete Research Articles

Poromechanical approach to blast‐induced dynamic fracture in concrete

AbstractThis study introduces a novel poromechanical approach to analyze blast‐induced dynamic fracture in concrete considering gaseous kinetics. The objective is to establish a framework for examining the fracture mechanisms during demolition. The simulation employs finite element analysis, incorporating three‐dimensional non‐orthogonal multidirectional cracks induced by gas inflation, through which the gaseous media flows too. The study investigates the principles governing crack network development and the influence of pressurized gas using a multiphase scheme and verifies its findings experimentally. It was also emphasized that benchmark blast experimental data are essential for validating the model, for practical applications in the demolition and renovation of existing structural concrete.

Dynamic Fracture of Concrete–3D Numerical Study of Compact Tension Specimen

The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, and ductility, and, second, there are inertia forces activated. Both influences are clearly demonstrated in experiments. For concrete structures, which exhibit damage and fracture phenomena, the failure mode and cracking pattern depend on loading rate. Moreover, theoretical and experimental investigations indicate that after the crack reaches critical speed of propagation there is crack branching. The present paper focuses on 3D finite-element study of the crack propagation of the concrete compact tension specimen. The rate sensitive microplane model is used as a constitutive law for concrete. The strain-rate influence is captured by the activation energy theory. Inertia forces are implicitly accounted for through dynamic finite element analysis. The results of the study show that the fracture of the specimen strongly depends on the loading rate. For relatively low loading rates there is a single crack due to the mode-I fracture. However, with the increase of loading rate crack branching is observed. Up to certain threshold (critical) loading rate the maximal crack velocity increases with increase of loading rate, however, for higher loading rates maximal velocity of the crack propagation becomes independent of the loading rate. The critical crack velocity at the onset of crack branching is found to be approximately 500 to 600 m/s.

Element-free Galerkin methods for dynamic fracture in concrete

Mixed-mode dynamic crack propagation in concrete is studied using the element-free Galerkin (EFG) method. The EFG methodology allows for arbitrary crack growth in terms of direction and speed. A fracture process zone (FPZ) model is used for fracture in concrete. Comparisons are made to mode I and mixed-mode experiments on concrete three-point-bend specimens. Good agreement is acheived with the experimental results.

Element-free galerkin methods for dynamic fracture in concrete

Mixed-mode dynamic crack propagation in concrete is studied using the element-free Galerkin (EFG) method. The EFG methodology allows for arbitrary crack growth in terms of direction and speed. A fracture process zone (FPZ) model is used for fracture in concrete. Comparisons are made to mode I and mixed-mode experiments on concrete three-point-bend specimens. Good agreement is acheived with the experimental results.

Numerical Simulation of Mode 1 Dynamic Fracture of Concrete

Nonsingular and singular fracture process zones (FPZ) are used to replicate numerically, dynamic fracture of displacement‐controlled and drop‐weight three‐point bend, concrete specimens and crack‐line wedge‐loaded, double‐cantilever beam (CLWL‐DCB) concrete specimens. An inverse procedure, which is based on dynamic finite element analysis, is used to match the measured load, load‐line displacement and three strain histories of the fracturing specimen. This numerical analysis shows that the singular‐FPZ model provides the most realistic simulation of dynamic fracture of concrete. The resulting constitutive relation between the crack closure stress and crack opening displacement for the sigular FPZ model is geometry and strain rate‐independent. The dynamic stress intensity factor, however, is strain rate‐dependent.