Effects of transverse reinforcement on flexural behaviour of high-strength concrete columns

Abstract

This experimental investigation was conducted to examine the behaviour of eight one-third scale columns made of high-strength concrete (HSC). Each column was subjected to a constant axial load corresponding to 30% of the column axial-load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement ( ρ s=1.58, 2.25%), tie configuration (Type H, Type C and Type D) and tie yield strength ( f yh=549 and 779 MPa). Test results show that the flexural strength of every column exceeds the calculated flexural capacity based on the equivalent concrete stress block used in the current design code. Columns with 42% higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. With an axial-load of 30% of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 549 MPa. Analysis of the flexural strength using the confinement model presented by Yong et al. enabled the experimental moment capacities to be predicted accurately.