The study proposes a practical strengthening method for improving the seismic behavior of reinforced concrete square columns using spiral as lateral reinforcement in moderate seismic zone regions. Two specimens one without ductile detailing and the other with ductile detailing designed as per Indian standard specifications and six specimens with spiral ties (in one direction and cross directions) at 25°, 35°, and 45° of inclination were tested under constant axial load and cyclic lateral loads to study the feasibility of the provision of spiral ties as a seismic-strengthening method. The important variable used was the angle of inclination of the spiral bars. Test results revealed that the column specimen strengthened with cross spirals at 25° had almost similar performance and ductility behavior when compared with the control specimen with ductile detailing and specimen strengthened with cross spirals at 35° had better performance and ductility behavior when compared with the control specimen without ductile detailing and can be adopted in moderate seismic regions. Considering the enhanced behavior, such as the strength, stiffness, and ductility, along with the construction easiness, for better performance of columns in moderate seismic zones, angle of inclination of 35° is sufficient.

中文翻译：

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螺旋钢筋约束钢筋混凝土柱的性能

该研究提出了一种实用的加固方法，以提高在中等地震带地区使用螺旋作为横向钢筋的钢筋混凝土方柱的抗震性能。在恒定轴向载荷下测试了两个试件，一个没有延性细部，另一个具有按照印度标准规范设计的延性细部，以及六个具有 25°、35°和 45° 倾角的螺旋拉杆（在一个方向和横向）的试件和循环横向荷载来研究提供螺旋拉杆作为抗震加固方法的可行性。使用的重要变量是螺旋杆的倾斜角度。试验结果表明，25°交叉螺旋加固的柱试件与具有延性细部的对照试件具有几乎相似的性能和延性行为，35°交叉螺旋加固的柱试件与对照相比具有更好的性能和延性行为试件无延性细部，可用于中等地震区。考虑到强度、刚度和延展性等增强的行为以及施工的容易性，为了在中等地震带中获得更好的柱子性能，35°的倾斜角就足够了。