钢筋混凝土板柱中节点冲切破坏面割线倾角研究

To investigate the punching failure of slab-column connections in cases where the longitudinal tensile reinforcement of the slab yields, a novel experimental approach is proposed. This experimental setup facilitates the application of bending moments at the free end of the slab and vertical loads around the perimeter of the slab. Following this experimental design, three slab-column connection punching tests were conducted, each with varying punching span ratios and relative compression zone heights. The findings from the tests reveal that, when the specimens reached peak loads, the longitudinal tensile reinforcement in the slab had yielded near the column edge. Additionally, an increase in the ratio of longitudinal tensile reinforcement from 1. 04% to 1. 25% corresponded to a decrease in the secant inclination angle of the punching failure surface from 46. 3° to 39. 4°. Building upon the data from this study and compiled punching tests, a calculation formula was developed to determine the secant inclination angle of the punching failure surface, considering the punching span ratio, concrete compressive strength, longitudinal tensile reinforcement ratio, and slab effective depth. Furthermore, a calculation formula for the punching capacity of the slab was established, taking into consideration the punching span ratio, relative height of the compression zone, and secant inclination angle of the punching failure surface.