Experimental study on shear mechanism of reinforced concrete beams with stirrups

Taking shear span ratio, concrete strength and stirrup ratio as variables, shear tests of 16 simply supported reinforced concrete beams under concentrated loads were conducted to study the shear mechanism of reinforced concrete beams with stirrups. HRB600 was used as longitudinal tensile rebar to avoid the high ratio of longitudinal reinforcement. Through embedded resistance strain gages inside the slotted stirrups, the shear force of concrete and stirrups can be obtained by measuring the shear capacity of the stirrups. The test results show that the shear span ratio and the strength of concrete have significant effects on the proportion of the shear force shared by concrete and stirrups in total shear force, and the two variation trends are opposite. When the shear span ratio is relatively small, the stirrups can improve the shear bearing capacity of concrete, but the shear force contributed by stirrups is small, and even cannot reach their yield strength. When the shear span ratio is relatively large, the inclination angle of the inclined crack is less than 45°, the actual number of stirrups intersecting the crack is more than the number calculated according to 45°, and the shear force contributed by the stirrups is larger. Compared with the beams without stirrups, the shear force shared by concrete in large-span beam with stirrups is reduced. Based on the experimental research, the experimental data of 369 beams with stirrups at home and abroad were collected. And the formulas for calculating the shear capacity of beams with stirrups were obtained by statistical analysis method, which are more reasonable and safer than those proposed in GB 50010—2010 ‘Code for design of concrete structures’. © 2022 Science Press. All rights reserved.