| The development of a comprehensive model for concrete confined by Fiber Reinforced Polymer (FRP) is presented. The model is applicable to both circular as well as rectangular concrete columns retrofitted using FRP jackets. The research consists of three phases.; In the first phase, an extensive experimental program, using 7-million pound capacity compression machine, was conducted to develop the experimental data. A total of 81 large un-reinforced concrete circular, square and rectangular columns, as well as 30 standard 6&inches; x 12&inches; concrete cylinders, were studied. All specimens were wrapped with FRP jackets and tested under pure axial load. The experimental study is unique due to the inclusion of large-scale specimens of the most practical concrete column shapes, which simulates full-scale building columns and half-scale bridge columns. The size effect between the small 6&inches; x 12&inches; cylinders and the large 16&inches; x 32&inches; circular specimens, both confined by FRP jackets, was addressed. Carbon/Epoxy and E-glass/Epoxy jackets, with different number of layers, were used to study different levels of confinement.; In the second phase, large reinforced concrete columns wrapped with FRP jackets were studied. A group of circular, square, and rectangular reinforced concrete specimens were tested. Both spiral and hoops were used as lateral reinforcement to study the difference in behavior. The square and rectangular columns were laterally reinforced using #2 ties. In addition, some octagonal (15&inches; x 30&inches;), and hexagonal (15&inches; x 30&inches;), un-reinforced columns were tested to address section geometry and its impact on the level of confinement achieved.; In the third phase of the study, the experimental data produced from the testing program, as well as other reliable data from the literature, were used to develop a comprehensive concrete confinement model. The proposed model shows an excellent correlation with the experimental findings. The proposed model was compared with other well-known concrete confinement models currently being used in the engineering practice. |
