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Abstract Modeling the mechanical behavior of reinforced concrete is still one of the most difficult challenges in the field of structural engineering. Concrete is a quasi-brittle material, its response under loading cannot be modeled as brittle behavior due to the presence of the large fracture zone, and on the other hand, it cannot be modeled using the classical mechanics of material techniques, such as plasticity theories, as they cannot handle materials with severe discontinuities such as cracks. The fundamental characteristics of concrete behavior have been established through experimental testing of plain concrete specimens subjected to specific, relatively simple load histories which revealed the highly nonlinear response of concrete especially close to and beyond the peak load. In order to describe the complex behavior of concrete, a large variety of constitutive models have been proposed to characterize the stress- strain relation and failure behavior of concrete. The presence of numerous models for describing concrete behavior reflects the difficulties encountered in formulating and interpreting such a behavior. The main objective of this research is to investigate the macroscopic behavior and progressive failure of reinforced concrete structures under static loading using the finite element techniques. The benefits and limitations of using these techniques for modeling the behavior of reinforced concrete have been studied. In addition, a comprehensive assessment of the reliability of numerical nonlinear analysis as a versatile tool for understanding the behavior of reinforced concrete beams under static loading have been addressed. The significance of this research lies in creating a road map for researchers using finite element codes such as ABAQUS in studying concrete behavior, showing the different stages for formulating each model accurately, the restrictions and limitations of each model, the accuracy of these models in interpreting concrete material behavior, and the difference between these models and their results when compared to the experimental results available in the literature. A comprehensive review of the input parameters of each model, and their influence on the obtained solution have been emphasized in order to achieve the goals of this study and guide researchers to build the most accurate and reliable model for each case study. In order to achieve the objectives outlined in this thesis, a calibration process have been conducted to verify the ability of the tested concrete models to describe concrete response under static loading, in addition a classification of the key parameters governing the construction of a sound and accurate model have been outlined. Furthermore, a detailed description for the modeling of three different reinforced concrete beams as case studies has been introduced. The first case study has been chosen to validate the three models offered by ABAQUS to study concrete behavior. The behavior of this case study was modeled using the different ABAQUS concrete models and a comparison has been conducted between the outputs of ABAQUS models, in order to demonstrate the drawbacks and limitations of each model. In addition, the findings of this comparative study have been used as a guide to construct the other two case studies by applying the most suitable model. The results of the applied model (Concrete Damaged Plasticity Model) are in good agreement with the experimentally documented results in the literature. The results of the model can be used in validating and guiding experimental work, in addition to exploring concrete response under complicated loading conditions such as the behavior of reinforced concrete deep beams with and without web opening, which have been studied under monotonic loading in comparison with the ACI 3\8-08 (Appendix A) and the Egyptian Code (203 - 2006) provisions. |