Experimental Study on Tightening Torque-Corner Compressive Pressure Relationship and Retention Performance of an SOS Reinforcement Device Under Cyclic Loading

In this study, the compressive pressure at the corner region induced by the tightening torque of an SOS reinforcement system is evaluated, and the structural behavior of the specimen and reinforced member under cyclic loading is investigated. The compressive pressure increased with increasing tightening torque, while residual displacement and gradual hysteresis-loop widening were observed after the fourth cycle. In the ninth cycle, stiffness degradation occurred, with a maximum displacement of approximately 19 mm and a residual displacement of approximately 4 mm. Despite the progressive damage to the specimen, the axial strain of the SOS member showed no abrupt relaxation, indicating that the initial prestress of the device was retained within the tested load range.