Investigation of the Behavior of Reinforced Concrete Deep Beams Strengthened with CFRP and GFRP Bars

نوع: Type: Thesis

مقطع: Segment: Msc

عنوان: Title: Investigation of the Behavior of Reinforced Concrete Deep Beams Strengthened with CFRP and GFRP Bars

ارائه دهنده: Provider: Kayvan Jady

اساتید راهنما: Supervisors: Mostafa Moghadasi (Ph.D)

اساتید مشاور: Advisory Professors: Mahmoud Nili (Ph.D) , Fereydun Rezaei (Ph.D)

اساتید ممتحن یا داور: Examining professors or referees:

زمان و تاریخ ارائه: Time and date of presentation: November, 11, 2020 - 10

مکان ارائه: Place of presentation:

چکیده: Abstract: In recent years, with the discussion of improvement and strengthening of reinforced concrete elements by FRP fibers, a new season of studies has been formed in this field. Since that beams are part of the structural system, strengthening them can prevent the collapse and damage of reinforced concrete structures. Considering the dimension ratio of deep beams and high shear deformation, the main weakness of deep beams can be considered as low shear capacity compared to flexural capacity and consequent shear failure. To strengthen these concrete elements, several methods have been used, one of the most effective of them is the reinforcement of deep beams with the means of composite bars. Composite bars are used in various industries such as military, medical and construction due to their properties such as light weight, high strength, higher strength, tensile behavior and properties, better compression and adhesion than other fibers. Although many laboratory studies have been performed to better understand the behavior of reinforced deep beams, even the most comprehensive ones cannot fully cover the interaction of variables participating in the performance of these structures. In addition, real-scale laboratory studies are costly and time consuming, which limits the number of parameters to be evaluated, so numerical simulation is a powerful tool for laboratory studies, although the use of finite element methods requires validation of tasks. There is a laboratory. Despite what has been said, there is a lack of research in which the behavior of reinforced deep beams with CFRP and GFRP bars and steel bars has been investigated comparatively. In order to investigate the performance of this method, in this study, ABAQUS FEM software has been used, 18 deep beam element with simple support were modeled under two concentrated loads; In all loading patterns, the applied load range was applied uniformly so that the applied loads started from zero at the beginning of the analysis -- and increased linearly (Ramp) to the maximum value. The effect of CFRP, GFRP and steel bars was investigated using the nonlinear finite element method. The models were analyzed based on the plastic damaged-concrete model that can be used in static and dynamic calculations. 6 series of samples, each of them was modeled by three types of steel bars, CFRP and GFRP, were analyzed. For each sample, the force and location of the first crack, fracture mode and overload-displacement load diagram were determined to compare parameters such as maximum load capacity, absorbed energy, ductility and stiffness. Investigating the models found that the fracture modes in the elements are almost similar to each other, so that in deep beams, shear cracks were created at a 45-degree angle in the tensile region. Comparing the results of the analysis of the mentioned models regarding the carrying capacity, it was observed that among the used models, the S2 model experienced the largest increase in carrying capacity compared to the G2 model with a 59% increase. Regarding the absorbed energy in the S4 model, with the increase of the area under the curve, the absorbed energy increased by 208.44% compared to the G4 model. On the other hand, in examining the ductility of the modeled deep beams, it was observed that the S6 model has faced an increase of 118.89% compared to the G6. Further examination of the models showed that the hardness of deep reinforced concrete beams is approximately equal and in the range of 89 kN/mm. Also, the force required to create the first crack (Pcr) in steel-reinforced samples was higher than other models. In the end, according to the analysis, it was observed that steel bars have higher bearing capacity, absorbed energy and ductility than deep reinforced concrete beams reinforced with CFRP and GFRP bars. Key Words: Behavior of Reinforced Concrete Beam, Deep Beam, Reinforced Concrete Beam Strengthened, CFRP Bars, GFRP Bars

فایل: ّFile: Download فایل