Effect of Preexisting Cracks on Lap Splice Strength of Reinforcing Bars

The effect of preexisting subsurface cracks on the strength of lap splices was investigated. Ten full-scale beams with No. 11 (No. 36) bars and lap splice lengths of 33, 79, and 120 in. (838, 2007, and 3048 mm) were tested. The beams had mitigating features that prevented catastrophic failure upon propagation of the preexisting cracks, such as staggered splices and the presence of some reinforcement crossing the plane of the cracks. The effect of preexisting cracks on the bar stress at failure was found to be most severe for the shortest splices and not significant for the two other splice lengths evaluated. The effect was found to be dependent on the amount of reinforcement crossing the plane of the cracks. Splice strength was unaffected in beams with the largest amount of reinforcement, and reduced on the order of 50% in beams without any reinforcement crossing the plane of the cracks.