Mechanical performance of grout-filled coupling sleeves of electric resistance welded steel tube with interior projections and bond stress-slip relations of reinforcing bars in the splices under uniaxial tensile loads are discussed using the results of experimental studies, in this paper. Experimental variables adopted in the investigations are development length of reinforcing bars, kinds and compressive strength of grout as filler materials, some mechanical devices to improve the splice performance, and so on. Following, main conclusions are obtained. (1) The mechanical performance of the splices employed herein are improved significantly with increase in development length of reinforcing bar and compressive strength of grout. (2) Assumption of respective constant bond stress in pre-and post-yield region of reinforcing bars in the splices leads equations to estimate practically both load capacities and failure modes of the splices.
