螺旋箍筋约束高强混凝土柱轴心受压性能试验研究

The effects of concrete standard cube compressive strength (58.0-90.6 MPa), stirrup yield strength (480-1 219 MPa), stirrup volume ratio (1.00%-1.60%), and stirrup spacing (45-80 mm) on the bearing capacity and deformation capacity of high-strength concrete columns confined by spiral stirrups were studied through axial compression tests of 42 column specimens. The test results show that the confining stirrups may not yield when the confined concrete reaches the peak compressive stress. When the yield strength and volume ratio of the stirrups remain the same, the tensile strain in the stirrups decreases with increasing concrete strength as the confined concrete reaches the peak compressive stress. When the axial compressive strength of the unconfined concrete and the yield strength of the stirrups remain the same, an increase in the stirrup volume ratio causes increases in the peak compressive strain in the confined concrete, the corresponding transverse strain, and the tensile strain in the stirrups. The test results were then analyzed to determine the relationship between the stirrup tensile strain, stirrup volume ratio, concrete strength, stirrup yield strength, and stirrup spacing under peak compressive stress to establish a formula for the stirrup tensile strain. The formulas for the peak compressive stress, peak compressive strain, and characteristic parameters (axial compressive strain at 85% peak stress following peak compressive stress and axial compressive strain at 50% peak compressive stress following peak compressive stress) of the confined concrete were obtained by fitting. The stress-strain relationship of high-strength concrete columns confined with stirrups was finally derived considering the influence of the stirrup volume ratio, concrete axial compressive strength, stirrup spacing, and stirrup yield strength.