BOND-SLIP TESTING AND PERFORMANCE EVALUATION OF SEMI-RIGID FLANGE FOLDED WEB SHEAR KEYS

The shear key is crucial to the overall mechanical performance of the structure. A new type of semi-rigid connector-flange folded web shear key was proposed to determine the effective unity of higher bearing capacity and deformation. A total of five groups of specimens were designed, and the push-out test method was used to evaluate the ultimate bearing capacity, bond-slip process, failure mode, and strain distribution of the new shear key. The results show that before sliding, the embedded effect of the concrete and shear key is significant, and it has a significant sliding stiffness. After sliding, the steel plate in the middle of the opening of the outer folded plate buckles, which shows certain semi-rigid characteristics. Compared with equal-area studs, the bearing capacity of the new shear key is increased by more than 40%, and the deformation capacity exceeds 60 %, indicating good bond-slip performance. The constraint range of the shear key is greatly improved compared with the stud, and a trapezoidal area of constraint centered on the shear key is formed, accounting for more than half of the area of the concrete slab. Based on an experimental study, a practical calculation method of ultimate bearing capacity of the shear key is proposed, which can meet engineering safety requirements. Based on the analysis of bond-slip characteristics of different forms of shear keys, compared with the rigid T-shaped shear key, the slip load and ultimate bearing capacity of the new shear key are found to be increased by 39 % and 74 %, respectively, and the deformation capacity is increased more than 10-fold. Compared with the flexible stud shear connectors, the sliding load is increased by 86 %, the ultimate bearing capacity is increased more two-fold, and the stiffness is increased by nearly five times. The device exhibits good comprehensive performance.