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Thermomechanics failure of RC composites: computational approach with enhanced beam model
Ngo, Minh,Ibrahimbegovic, Adnan,Brancherie, Delphine Techno-Press 2014 Coupled systems mechanics Vol.3 No.1
In this paper we present a new model for computing the nonlinear response of reinforced concrete frame systems subjected to extreme thermomechanical loads. The first main feature of the model is its ability to account for both bending and shear failure of the reinforced concrete composites within frame-like model. The second prominent feature concerns the model capability to represent the total degradation of the material properties due to high temperature and the thermal deformations. Several numerical simulations are given to confirm these capabilities and illustrate a very satisfying model performance.
Combined hardening and localized failure with softening plasticity in dynamics
Do, Xuan Nam,Ibrahimbegovic, Adnan,Brancherie, Delphine Techno-Press 2015 Coupled systems mechanics Vol.4 No.2
We present for one-dimensional model for elastoplastic bar with combined hardening in FPZ - fracture process zone and softening with embedded strong discontinuities. The simplified version of the model without FPZ is directly compared and validated against analytical solution of Bazant and Belytschko (1985). It is shown that deformation localizes in an area which is governed by the chosen element size and therefore causes mesh sensitivity and that the length of the strain-softening region tends to localize into a point, which also agrees with results obtained by stability analysis for static case. Strain increases in the softening domain with a simultaneous decrease of stress. The problem unloads elastically outside the strain-softening region. The more general case with FPZ leads to more interesting results that also account for induced strain heterogeneities.
An embedded crack model for failure analysis of concrete solids
Jaka Dujc,Boštjan Brank,Adnan Ibrahimbegovic,Delphine Brancherie 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.4
We present a quadrilateral finite element with an embedded crack that can be used to model tensile fracture in two-dimensional concrete solids and the crack growth. The element has kinematics that can represent linear jumps in both normal and tangential displacements along the crack line. The cohesive law in the crack is based on rigid-plasticity with softening. The required material data for the concrete failure analysis are the constants of isotropic elasticity and the mode I softening curve. The results of two well known tests are presented in order to illustrate very satisfying performance of the presented approach to simulate failure of concrete solids.
Localized failure in damage dynamics
Do, Xuan Nam,Ibrahimbegovic, Adnan,Brancherie, Delphine Techno-Press 2015 Coupled systems mechanics Vol.4 No.3
In this work we present a one-dimensional damage model capable of representing the dynamic fracture for elastodamage bar with combined hardening in fracture process zone - FPZ and softening with embedded strong discontinuities. This model is compared with another one we recently introduced (Do et al. 2015) and it shows a good agreement between two models. Namely, it is indicated that strain-softening leads to a sensitivity of results on the mesh discretization. Strain tends to localization in a single element which is the smallest possible area in the finite element simulations. The strain-softening element in the middle of the bar undergoes intense deformation. Strain increases with increasing mesh refinement. Strain in elements outside the strain-softening element gradually decreases to zero.
Ba-Hung Pham,Luc Davenne,Delphine Brancherie,Adnan Ibrahimbegovic 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.4
In this paper, we present a new finite Timoshenko beam element with a model for ultimate load computation of reinforced concrete frames. The proposed model combines the descriptions of the diffuse plastic failure in the beam-column followed by the creation of plastic hinges due to the failure or collapse of the concrete and or the re-bars. A modified multi-scale analysis is performed in order to identify the parameters for stress-resultant-based macro model, which is used to described the behavior of the Timoshenko beam element. The micro-scale is described by using the multi-fiber elements with embedded strain discontinuities in mode 1, which would typically be triggered by bending failure mode. A special attention is paid to the influence of the axial force on the bending moment - rotation response, especially for the columns behavior computation.