RESEARCH ON CONFINING REINFORCEMENT FOR HIGH-STRENGTH CONCRETE COLUMNS WITH HIGH-STRENGTH STIRRUPS

Quasi-static test results of 98 rectangular and 11 circular high-strength concrete (HSC) columns with high-strength stirrups (HSS) are collected to study the confining reinforcement for ductile HSC columns. Based on the analysis of test results, it is concluded the parameters that have significant influences on the ductility of HSC columns are characteristic value of stirrups, axial load ratio, longitudinal reinforcement and concrete cover thickness. Based on regression analysis, design equations and design details are suggested, which stipulate the amount of confining reinforcement required to achieve ultimate drift ratios of 2% and 3% with 85% assurance rate for HSC columns. The design equations and details can be applied to the columns with concrete compression strength of 40MPa―110MPa, stirrup yield strength of 400MPa―800MPa and experimental axial load ratio of 0―0.6.