Abstract
Behavior of reinforced concrete beam cannot be captured by elastic damage models or elastic-plastic constitutive laws only. When these two models coupled, load deflection behavior of reinforced concrete can be observed through numerical modeling. Thus, using concrete damage plasticity approach in finite element modeling can lead researches for sufficient numerical results when compared to experimental tests. In order to determine the material damage model of concrete, some laboratory tests are required. This paper offers an equation for damage parameter to capture damage behavior. In addition, modeling strategies are developed by checking the model sensitivity against mesh density, dilation angle and fracture energy of concrete. Finite element models are verified by three different experimental tests. In this study ABAQUS finite element software is employed to model reinforced concrete beam with concrete damage plasticity approach. This study shows that difference between the results from numerical models and experimental tests are in acceptable range.
1. Introduction
Constitutive behavior of concrete is very difficult to capture by using elastic damage models or elastic plastic laws. In elastic damage model irreversible strains cannot be captured. It can be seen in Fig. 1(b) that a zero stress corresponds to a zero strain which makes damage value to be overestimated. On the other hand when elastic plastic relation is adopted the strain will be overestimated since the unloading curve will follow the elastic slope (Fig. 1(c)). Concrete Damage Plasticity (CDP) model which combines these two approaches can capture the constitutive behavior of experimental unloading (Fig. 1(a)) (Jason et al., 2004).
6. Conclusions
Three different experimental tests are verified by using modeling strategies explained in the previous sections. Results show that experimentally observed loading trends and magnitudes for entire loading range of RC beams can be captured by employing CDP modeling approach. Basically mesh density, dilation angle and concrete fracture energy are calibrated to develop modeling strategies. It is obvious that if material properties and geometrical information about real test are given in detail then numerical models give better results than those with missing information. Also this study proves that defining damage parameters for compression behavior with proposed equation gives satisfactory results. But this equation can be improved with real test results for further investigations.
