Stress versus strain relationship of high strength concrete under high lateral confinement

A common application of high strength concrete (HSC) is in columns subjected to large compressive forces. However, a major problem is the insufficient ductility available in HSC columns. To determine the required lateral reinforcement to maintain sufficient ductility, a good understanding of the stress-strain behaviour of confined concrete needs to be established. This paper describes a testing program carried out to obtain experimental data of complete (ascending and descending) stress-strain relationships between axial stress, axial strain and lateral strain for HSC. Compressive strengths of concrete tested were 100 MPa and 60 MPa. The confining pressures used were 4 MPa, 8 MPa and 12 MPa. A total of 18 stress-strain curves are presented. The experimental results obtained seem to indicate that, for high confining pressures, the lateral strain at peak stress for 100 MPa concrete was 20% less than that of the 60 MPa concrete.