Influence of prism geometry on the compressive strength of concrete masonry

The compressive strength of concrete masonry depends on the dimensions of the test prisms. The available international masonry codes apply correction factors based on the height-to-thickness ratio to modify the strength obtained from different sizes of prisms. In this study, finite element models were developed to investigate the accuracy of this approach. Simplified micro-modeling method was used to simulate the behavior of masonry prisms which was verified against experimental results. A parametric study was then performed to examine the effect of key parameters on the compressive strength of masonry. The effect of the length-to-thickness ratio of masonry prisms was found to be significant on the compressive strength and should be considered together with the well understood effect of height-to-thickness ratio to calculate the correction factors. It was also shown that the current correction factors provided in the masonry codes lead to overestimating the strength of masonry prisms. New correction factors have been proposed accounting both the height-to-thickness and length-to-thickness ratio to reliably and safely estimate the compressive strength of masonry prisms.