×
The submission system is temporarily under maintenance. Please send your manuscripts to
Go to Editorial ManagerThe principle aim of this research is concentrated to analyze the effect of cracks and their propagations on the mechanical behavior of a quasi-brittle material such as concrete. The singularity (stress concentration to infinity at the tip of crack) is avoided by using the principal of fracture energy with the fictitious crack approach. The concrete crack is divided into two major zones; the first one is the fracture zone (a combination of bridging effect and the cohesive microscopic cracking) which obeys a special law permitting the transmission of stress across the two faces of crack, this zone is considered as partially cracked concrete. When the opening of the crack exceeds a specific value, this zone is converted to a real crack (an open crack) and cannot transmit any stress across the two faces of a crack. The program of finite element used in this research is prepared by the researcher using discrete-crack approach with the experimental data obtained from the flexural test on notched beam loaded under three-point bending, where fracture mode I is dominated. The response of the applied load-crack mouth opening displacement (CMOD) with appropriate fracture energy is selected. The results show that the cohesive microscopic cracking zone for the plain concrete is very wide. The cohesive stress distributions across the microcracks with the corresponding crack openings are drawn from the first crack appearance till the beam failure.
This research concerns with the fracture behavior of reinforced concrete beams without shear reinforcement numerically. The software ABAQUS is adapted to simulate the crack propagation using the eXtended Finite Element Method (XFEM), taking into account materials nonlinearities using concrete damage plasticity CDP criteria. XFEM is used to solve the discontinuity problems in the simulation. The maximum principal stress failure criterion is selected for damage initiation, and an energy-based damage evolution law based on a model- independent fracture criterion is selected for damage propagation. The traditional nonlinear finite element analysis is used to specify the crack initiation position, which is required to specify the crack location in the analysis of beams using XFEM. Three-dimensional reinforced concrete beam models are investigated subjected to three and four-point loading tests. Simply supported beams under the effect of applied static load are investigated. An elastic perfectly plastic model is used for modeling the longitudinal steel bars. The main variables considered in the study are beam depth and the shear span with beam length. The numerical results are compared with the available experimental results to demonstrate the applicability of the model. The XFEM provides the capability to predict the concrete member fracture behavior.