Abstract:
Ultra high performance concrete (UHPC) is a kind of cement-based material with high strength, high toughness and high durability. To study the lap-spliced bond performance of steel bars in UHPC, 21 groups of lap-spliced specimens were tested considering the parameters of lap length, fibers content and stirrups ratio. 3 groups of pull-out specimens considering a parameter of anchorage length were conducted to be control groups. Two failure modes, those are splitting-pull-out failure and steel-bar-rupture failure appear. The average bond strength decreases with the increase of embedded length and increases with the increase of stirrup ratio. The steel fibers enhance the confinement for UHPC. Increasing the stirrup ratio and fiber content can reduce the lap-spliced length of the steel bars in UHPC. Combining with the previous research, average bond strength and development length as well as splice length formulas were fitted. Simplified algorithms of development length and splice length were proposed according to the Code for Design of Concrete Stuctures, and the results agree well with the test results.