Lap Strength of Headed Steel Reinforcements with Confinement
In this research, the experimental works were conducted to study the lap strength of the headed reinforcements with confinement provided by stirrups or tie-down bars. Five lap splice specimens were tested. Wide beam specimens were fabricated with a lap splice at mid-span. They were loaded in flexure, placing the lap splice in tension. The variables in this study were: confinement details (stirrups, tie-down bars with stirrups) and lap length (10, 14 times the diameter of reinforcement). Specimens were instrumented to measure the load on the specimen, strain along the reinforcements with in the lap zone, and mid-span deflection. The cracking behavior was also observed and recorded. The following conclusions were drawn from the test results in this study; 1) The initial crack of the specimens lapped developed at the heads of reinforcements. The specimens failed by the crack with the struts acting between the opposing heads of lapped reinforcements. 2) Bond stress and confinement details contributed to increase strength and deformation. 3) CCD method evaluated the maximum strength as 4.95∼6.87 times the test maximum strength. The ratios of the test maximum strength and the maximum strength assumed by ACI 318-08 for headed deformed bars were 1.38∼2.01.
A. Saimoto and M.H. Aliabadi
S. H. Kim et al., "Lap Strength of Headed Steel Reinforcements with Confinement", Key Engineering Materials, Vols. 452-453, pp. 17-20, 2011