Stress–strain model for FRP-confined circular concrete columns developing structural softening behavior

• Autor(a) principal: Shayanfar, Javad
• Data de Publicação: 2024
• Outros Autores: Barros, Joaquim A. O., Rezazadeh, Mohammadali
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/1822/88667
• topic: Concrete; Stress-strain model; FRP confinement; Softening behavior; Fiber-reinforced polymer (FRP) confinement; Engenharia e Tecnologia::Engenharia Civil

Even though several stress-strain models have been proposed for FRP-confined concrete columns subjected to axial compressive loading, very few models are able to predict an axial response featuring post-peak strain softening behavior. Furthermore, the reliability of most of these models are limited only to a certain concrete strength class (either normal- or high- or ultrahigh-strength concrete). This study aims to develop an analytical model for the determination of the axial response of FRP-confined concrete applicable to the cases with different levels of confinement stiffness and concrete strength. For this purpose, this research proposes a new confinement stiffness threshold dependent on the coupled concrete strength and column dimension size effects, to classify quantitatively FRP-confined concrete’s behavior in two distinguished subcategories: strain hardening and strain post-peak softening behavior. For FRP-confined concrete with strain hardening response, a parabolic-linear stress-strain relation is developed where a new formulation is derived for the slope of the linear second portion, calibrated by 583 test data. To simulate FRP-confined concrete with strain post-peak softening behavior, a new methodology is proposed whose key components are calibrated by using 121 test data. With these features, the proposed model is able to objectively account for the integrated influences of concrete strength and confinement stiffness on stress-strain response. The predictive performance of the developed stress-strain model is evaluated by comparing the predictions of a wide range of relevant experimental test data, which confirms the model’s reliability and accuracy. Compared to the other existing stress-strain models, the proposed model provides an improved performance.