Modelagem elastoplástica de colunas de concreto confinadas por polímeros reforçados com fibra

Abstract

The effect of confinement improves the strength and ductility of concrete columns. Most of the existing predictive models of the stress-strain diagram of confined concrete are semi empirical and do not allow a direct extrapolation to materials with distinct properties of the ones used in tests. Therefore, a search for models based in rational theories such as continuum mechanics, as is the Plasticity Theory, is conducted, targeting a more efficient performance and ample applicability. In this work, a study of the behavior of confined concrete columns with circular or square sections, laterally confined by sheets of fiber reinforced polymers (FRP) and submitted to concentric and monotonic compression axial load, is carried out, based on Plasticity Theory. In this study, the behavior of confined concrete is assumed as a Drucker-Prager plasticity model, while the confining material is considered linear elastic. The analysis is developed through a semi analytical incremental-iterative procedure that allows the description of the stress-strain behavior of the mentioned columns. To consider columns with square sections, a strategy of homogenization of the stress and strain fields throughout the section is applied, so that the procedure of analysis is unified and used to describe the behavior of columns with circular or square sections. To validate and verify the proposed model, comparisons of stress-strain diagrams are made with the results of the proposed model and other existing models and experimental data. These results show a satisfactory performance of the proposed model in describing the behavior of circular and square columns.