Doctor of Philosophy (PhD)


Civil and Environmental Engineering

Document Type



A plastic-damage model for plain concrete is developed in this work. The model uses two different yield criteria: one for plasticity and one for damage. In order to account both for compression and tension loadings, the damage criterion is divided into two parts: one for compression and a second for tension. The superscripts (+) and (-) in this work are used to represent tension and compression cases, respectively. The total stress is decomposed into tension and compressions components. The total strain is decomposed into elastic and plastic parts. The strain equivalence concept is used such that the strains in the effective (undamaged) and damaged configurations are equal to each other. The formulations are extended from the scalar damage to the second order damage tensor. The Lubliner model for plasticity is used in this work. A numerical algorithm is coded using the user subroutine UMAT and then implemented in the advanced finite element program ABAQUS. The numerical simulations are conducted for normal and high strength concrete. The proposed model is also used to compare between the high strength and normal strength concrete. In addition, the three point and four point notched beams are used in the analysis in order to obtain the damage evolution across the beams. Two different meshes, a coarse and a dense, are used for the beams analysis. Beam damage evolution for different displacements is shown at different steps of loading. In all the examples, the results are compared with available experimental data. The results show very good correlation with the experimental data. Damage evolution across the beams is very similar to the experimental crack band. This indicates the accuracy of the method. Computationally, the model is also efficient and consumes minimal computational time.



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Committee Chair

George Z. Voyiadjis