Mechanical Properties of Deformed Rebars Lapped in Spiral Stirrups Confined Grout-Filled Corrugated Pipes

60 sets of 180 specimens were designed and manufactured to verify the reliability of the splice in which the rebars lapped in spiral stirrups confined grout-gilled corrugated pipes. The specimen parameters include longitudinal reinforcement diameter, concrete strength, and spiral rebar diameter and screw pitch. The monotonic tension loading test results indicated that the ultimate tensile strength of specimens all exceeded the 150 percent of the specified yielding strength and 110 percent of specified tensile strength of the lapped rebars. For the splice specimens with lapped rebar diameters of 10 mm and 12 mm, the effect of the spiral stirrups on the tensile strength of the splice specimens was not obvious. For the specimens with a rebar diameter of 14 mm, larger volume ratio and smaller screw pitch of the spiral stirrups could result in less damage of the concrete block under tension load. For a similar reinforcement ratio, it was recommended to use a smaller rebar diameter and screw pitch. When the spiral configuration was d4@50 and the nominal diameter of the longitudinal reinforcement was not more than 14 mm, the lap length could be taken as the basic anchorage length of rebar.