Experimental Research on Damage Characteristics of Stirrup-Confined Concrete Under Uniaxial Compression

The experiments were designed for the characterizing the damage progress in the stirrup confined concrete. Through the uniaxial compression test, the parametric study was conducted to investigate the effects of loading rate, concrete strength, stirrup diameter, volume stirrup ratio on the mechanical properties and damage behaviors of the confined concrete. The experimental results were analyzed and demonstrated that: 1) with the increase of loading rate, the elastic deformation stage of concrete is shortened; and the plasticity of the whole damage process is weakened; moreover, the damage shows more brittle patterns. At low loading rate, the local failure and shear failure were mainly observed. When the loading rate is reaching at a high level, the longitudinally splitting mainly occurs. 2) Increasing the yield strength of stirrups is equivalent to the enhancement of the lateral confining pressure during the damage process of concrete, which plays an essential role in restraining the damage of the sample; 3) With the increase of stirrup ratio, the confinement effect of stirrups on the damage process is becoming more obvious, which effectively constrains the damage evolution process. 4) The samples with higher strength concrete show more brittle behavior and faster crack development during axial compression. Appropriate increase of concrete strength is beneficial to cooperative work with stirrups to restrain the evolution of damage.