This paper reports on a study to develop a new design equation for compression lap splices. Current design codes allow a compression lap splice to be calculated to be longer than a tension lap splice in high-strength concrete because the provisions for compression splices do not properly consider the effects of the compressive strength of the concrete and end bearing. An experimental study was conducted using compressive concrete strengths of 40 and 60 MPa (5800 and 8700 psi) without transverse reinforcement. A design equation was derived for compression lap splices without transverse reinforcement through regression analysis of the test results. The splice strength in compression was found to be evaluated with the square root of the compressive strength of the concrete. Spacing between bars had little effect on the splice strength. The bar stresses developed by bond were nearly identical to those calculated by the ACI 408 equation. Therefore, the strength increase in the compression splices is solely attributed to end bearing. An equation for a splice length in compression was proposed through a regression analysis for 30 specimens in which splitting failure occurred. Using the 5% fractile coefficient of 0.8, the splice length calculated by the proposed equation has a reliability equivalent to reinforcing bars.
