Influência do confinamento na ductilidade e redistribuição de momentos em vigas de concreto com armadura de GFRP

Abstract

The present work conducts the analytical and experimental study of concrete beams, reinforced with Glass Fiber Reinforced Polymer bars (GFRP), subjected to flexure Once non-metallic reinforcement has no plastic behavior, ductility – a crucial characteristic for reinforced concrete elements – and its favorable effects such as warning of failure and redistribution of forces in statically indeterminate structures are initially not observed in structural elements of this type. Among the strategies that can be used to improve this behavior, confinement of concrete is here studied to increase the ductile behavior, and it is achieved using GFRP stirrups in the flexural zone of the beams. The experimental program developed involved the test of 15 beam models, with longitudinal and transverse reinforcement in GFRP, eleven of which were statically determinate and four statically indeterminate. For the statically determinate beams, the main objectives were to verify load-carrying capacity, modes of failure, and behavior regarding maximum vertical displacements, crack widths, and deformations in both reinforcement and concrete. This was considered across different reinforcement arrangements, including under-reinforced, over-reinforced sections, and various configurations and spacings of confinement stirrups. For the statically indeterminate beams, the campaign aimed to study moment redistribution and behavior regarding flexural stiffness degradation due to cracking. The test results and their interpretation led to the conclusion that solely using stirrups, without other strategies reported in the literature, is sufficient to promote improvement in the ductile behavior of elements. This facilitates better control of failure, cracking, and allows for moment redistribution in statically indeterminate beams.