In recent years, emphasis has been made on studying the effect and behavior of beams under pure torsion, which required the emergence of different types of strengthening. Because of concrete's poor tensile strength, fiber can be added with high or low percentages. This paper aimed to study the torsional behavior of reinforced concrete beams and the jacketing technique. Reinforced beams were strengthened using a layer of Slurry Infiltrated Fiber Concrete (SIFCON) and with different types of fiber. SIFCON is a special type of fiber concrete that contains a high percentage of fiber. It is an effective substance used for repair and strengthening. The finite element (FE) method through ABAQUS software is carried out to test seven samples previously tested experimentally. Reasonable agreement was acquired between the ultimate torque and angle of twist of FE numerical models and found experimentally, in which the value of the mean and coefficient of variations were 0.998 and 0.247 %, respectively for the ultimate torque, whilst for the angle of twist, the value of the mean and coefficient of variation were 0.945 and 3.823 %, respectively. The effect of increasing longitudinal reinforcement ratio is found to be higher for torsional unreinforced beams and marginal for other beams for the selected range of reinforcement ratio or diameter (8 to 12 mm bar diameter). The effect of thickness of the SIFCON layer on the behavior is found to be higher for steel fiber SIFCON and lower for hybrid fiber SIFCON jacketing. The effect of hybrid fiber on behavior is studied.