عنوان مقاله [English]
In general, reinforced concrete elements tend to be very crisp, and this phenomenon is most evident when shaken. One of the advantageous of concrete enclosure is the increased concrete strength and concrete ductility which, if the concrete is properly enclosed and the seismic forces cause the concrete to be drilled, the enclosed concrete will resist well. The best way to do this is to use spiral stirrup. In this study, the effect of spiral with regard to the step variables of the spiral and the angle of the bolts on the shear and torsional capacity of rectangular reinforced concrete beams is investigated. ABAQUS finite element software was applied to simulate the samples. The results showed that the angle of cracks created in the specimens with closed stirrup was greater than that of the corresponding specimen (equal distance between the bends and the closed stirrup) with the spiral, and the use of stirrups both in the closed and in the bends situation, have increased the shear and torsional capacity of reinforced concrete beams. This research presented that reinforced concrete beams containing spiral stirrups had greater shear and torsional capacity than those of equipped with the closed stirrups. The use of closed stirrup and spiral stirrup with a step spacing of 80 mm have increased the shear capacity of reinforced concrete beams by 52% and 59%, respectively, which is a significant difference , and the shear and torsional capacity of reinforced concrete beams decrease with increasing step distance. By increasing the distance between the turns from 80 mm to 150 mm, the shear capacity of reinforced concrete beams is reduced by 30%, which is a significant amount. According to the results, the optimum spiral angle that best fits the rectangular reinforced concrete beams is 80 degrees. In this case, the angles of the diagonal cracks are lower than the other cases, and its shear and torsional capacities are significantly greater than the other specimens with equal steps and different angles.