Assesment of Codal Provision for SFRC Beam in Minimum Shear

Natural fibres (straw, chip, horse tail, goat hair and plume, etc.), was being used from ancient time for construction purposes. Inspired from ancient time, artificial fibres (vitreous, synthetic, carbon and steel fibre, etc.) are commonly used nowadays in order to improve the mechanical properties of concrete.

Literature has suggested that concrete matrix with steel fibre commonly known as Steel fibre reinforced concrete (SFRC) have enhanced flexural as well as shear behaviour as compared to conventional reinforced concrete (RC). Also it is recommended by ACI building code that steel fibre can use as minimum shear reinforcement in RC beams. In the present study, the experimental results for assessment of ACI building code provisions allowing the use of deformed steel fibres as minimum shear reinforcement in RC beams are presented. Hooked end steel fibres of length 35 mm and 60 mm have been used in concrete matrices at volume fraction of fibres ranges from 0.75 to 1.5% and 0.5 to 1% respectively. The experimental performance of the fibrous concrete beams has been compared with the Indian Standard and ACI codal provisions. It is found that in all the cases, even though at a volume fraction of 0.5%, lower than the ACI code-specified lower limit of 0.75%, the measured shear strengths were higher than the predicted values as per the ACI building code, Indian standard code, as well as from the lower bound value of 0.3√fc′MPa (3.5√fc′ psi). Also confirmed multiple diagonal cracking having crack width lower than the specified permissible values. On the basis, it is suggested that there is a need of relook into codal provisions of ACI.