Investigations on Minimum Flexural Reinforcement of HSC Beams

The rational behind providing minimum reinforcement is based on cracking moment of the section. Generally mini-mum reinforcement provided will be 20 % higher than cracking moment of the section. It has been observed from the literature that there are several parameters which affect the cracking moment such as concrete grade, depth of the section and fracture energy or the primary factors. It is also been observed there are secondary factors such as repeated load-ing, deformation and crack width sometimes become important. The minimum and maximum limits on longitudinal and transverse reinforcement ratios provided for reinforced concrete flexural members in the IS Code is based on tests conducted on normal strength concrete, and hence not applicable to high strength concrete beams. Hence comparing the provisions of other national codes, modifications to these limits are proposed for inclusion in the next edition of the code. These modified expressions are necessary in order to prevent sudden and brittle collapse of flexural members and also to provide ductile behaviour. A detailed analysis is been carried out to demonstrate the influence of the parameters while arriving minimum reinforcement to RC section