| Title |
An Experimental Study on the Lap Splice Performance of Headed Steel Reinforcements with Confinement Details |
| Keywords |
Headed Bars ; Lap Splice ; Confinement Details ; Bond Stress ; Bearing Stress |
| Abstract |
Headed bars have used to the anchoring of the tension or compression longitudinal bars and of the shear reinforcing bars. Recently, lap splices of headed steel reinforcements are attempted to the joints of precast concrete members and to the connections between old and new concrete members. Previous experimental and analytical researches for the lap splice of headed bars hadn't be studied except Michael's 2003. In this study, the lap splice performances of headed bars with confinement details are evaluated through the experimental works. Twelve 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: lap length(10 and 14 times the diameter of reinforcement), lapped reinforcements spacing (in contact or not), and confinement type (no confinement, transverse bars, transverse bars and hairpin confinement in lap zone). 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) Transverse bars and closed tie-down bars provide the effective confinement for lapped reinforcements, especially in the noncontact reinforcements. To improve the workability and the lap splice strength, it is effective that the headed reinforcements with the confinement reinforcements are placed in out of contact. 3) CCD method evaluated the maximum strength as 2.71∼5.26 times the test maximum strength. It was caused by the reduction of lap length where headed reinforcements were located less than 1.5 times lap length from three or more edges. For evaluation of the lap strength of headed reinforcements, it needs to consider the bearing stress of heads, the bond stress of reinforcements, and the confining effects. |