Size effect on compressive strength of plain and spirally reinforced concrete cylinders

Many experimental and theoretical investigations have been carried out to examine the reduction phenomenon of compressive strength of cylindrical concrete specimens with size, but up until now, an adequate analysis technique has not been developed: In this paper the fracture mechanics type size effect on the compressive strength of cylindrical concrete specimens was studied; with the diameter, the height/diameter ratio, and fire volumetric spiral ratio of cylinder considered as the main parameters. For this purpose, theoretical and statistical analyses were conducted. First, a size effect equation was proposed to predict the compressive strength of cylindrical concrete specimens with various diameters and height/diameter ratios. Second, the model equation derived from the plain concrete teres extended for predicting the compressive strength of spirally reinforced concrete cylinders. The proposed equation showed good agreement with the existing test results for concrete cylinders with and without spiral reinforcement.