Results of 51 tests on full scale columns with main reinforcement lap-spliced are presented. Difficulties in evaluating the strength of these specimens led to the development of an alternative method of calculation based on the stress-strain relationship for the concrete. The contribution of the end bearing of the reinforcement is evaluated, and the influence of splice length, concrete strength, and positioning of ties on splice strength is discussed. It is shown that bond strength and end bearing strength may each be regarded as the sum of two components, one related to bursting force and the other to concrete strength. A new type of bond test is used to show that more heavily ribbed bars develop greater average bond stresses. /Author/