Bond to concrete action of reinforcing bars with different deformation patterns

摘要

At present in Russia hot-rolled reinforcing bars are mainly manufactured using two deformation (rib) patterns, either with ring-like ribs of constant height or with two-row crescent-shaped ribs of 'European' style. Steel of both grades A400C and A500C can be produced with one or other of these rib patterns. Often it is difficult to identify on site an actual grade of rebars. To improve the situation a new specific deformation pattern for A500C grade steel was developed. The rebar-to-concrete interaction for the three patterns mentioned above is evaluated by means of the analysis of failure of concrete keys formed between transverse ribs of a steel bar. For this purpose the authors employed some principles of analysis that previously had been used for key joints of concrete floor panels. The bond behaviour is subsequently classified as 'rigid' or 'soft', the latter being considered as more favourable. The structural advantages of commercial production in Russia of A500CP grade reinforcing steel using the newly developed deformation pattern are described.