An Experimental Study on Shear Performance of Reinforced Steel Fiber Recycled Aggregate Concrete Filled Square Steel Tube Column of 50 MPa

Due to the unstable strength characteristics, the use of recycled aggregates is used only for non-structural members. To use recycled aggregates for structure members, shear performance evaluation experiments were conducted with the variables such as the replacement rate of recycled aggregates, steel fiber reinforcement, and shear span-to-depth ratio. A total of nine experiments were produced. The loading force proceeded at a speed of 0.03 mm/s, and the upper and lower points were asymmetrically arranged to make the shear force and bending moment act on the column without the actual axial force. At this time, the shear span (a) was adjusted according to the experimental variable shear span ratio, and the shear force diagram (SFD) and bending moment diagram (BMD) acting on the test object. The shear load was calculated as 0.875 P when the shear span ratio was 0.8, and 0.78 P when it was 1.6. The load and displacement of the experiments increased proportionally and acted elastically, and the load tended to increase gradually even after yield load. The shear strength and initial stiffness of the experiments in which the recycled aggregate replacement rate was a variable decreased as the replacement rate increased, and the shear strength and initial stiffness of the experiments reinforced with steel fibers increased compared to the non-reinforced experiments.