Effect of concrete strength on axial load response of circular columns

The behaviour of 10 spirally reinforced concrete columns and 5 plain concrete columns subjected to a concentric compressive load is investigated. The reinforced concrete columns were designed using the CSA A23.3-94 Standard. The experimental specimens were made of concretes with compressive strengths ranging from 35 MPa to 125 MPa. Two types of steel spiral reinforcement, Grade 400 and Grade 500, were used to investigate the ability of a higher yield strength steel to confine the concrete core.The response of the reinforced specimens is compared to predictions using a stress-strain model for confined concrete. The determination of the predicted response is based on the computation of a load-strain response using the effective confining stresses in the concrete core. The effects of the concrete compressive strength and the steel spiral tensile strength on the load-strain response are investigated. The peak loads of the spirally reinforced circular concrete columns are compared to the peak loads predicted by our current codes of practice.The response of the plain concrete columns with a wide range of specified compressive strengths are investigated. The peak loads of the plain concrete columns are predicted using various concrete stress-block factors provided by different codes