Lap Splices with High-Strength Concrete under Combined Flexure and Shear Loading

Abstract

Pure blending loading with a constant moment is frequently used as a loading method in experiments on lap splices. However, the stress state of the concrete around the lap splices must approximate that of the actual reinforced concrete members. This paper discusses the mechanical properties of lap splices based on results from combined flexure and shear loading tests conducted on high strength concrete (70-MPa grade) and normal strength concrete (30-MPa grade) beams with all lapped splices in a critical section with high stress. The results revealed differences in concrete strength in terms of the splice characteristics under flexure and shear stress. For example, the maximum flexural crack width in the high-strength concrete specimens under service loading is smaller than that of normal-strength concrete specimens. The expansion of the yield zone of the main reinforcement in lap splices was greater than that in normal-strength concrete specimens. Furthermore, the ratio of ultimate bond strength, which was obtained from the equation for bond splitting strength, to bond strength at the time of yield was small in the high-strength concrete specimens.