FLEXURAL CHARACTERISTICS OF STEEL FIBRE REINFORCED SELF COMPACTING CONCRETE BEAMS

Fibre reinforced concrete with steel fibres attracted the attention of engineers and researchers during the last five decades. In recent times, self compacting concrete has been accepted as a quality product and are widely used. A large number of studies are available with respect to several parameters viz., flexural strength, load deflection behaviour, toughness, ductility, crack control, effects of beam dimensions, concrete filling sequence, flexural toughness parameters etc., of Conventional Fibre Reinforced Concrete. The present study aims to study the flexural behaviour of SCC beams with steel fibres. An experimental programme has been designed to cast and test three plain SCC beams and six SCC beams with steel fibres. The experimental variables were the fibre content (0Vf%, 0.5Vf% and 1.0Vf %) and the tensile steel ratio (0.99%, 1.77% and 2.51%). The type of fibre configuration used was crimped fibre 30mm in length, an equivalent diameter of 0.5mm and with stirrups of 2L-8 mm dia bars @ 150mm c/c. The SCC design mix was proportioned to obtain a compressive strength of 70 MPa and yield strength of steel used was 595 MPa. The experimental constants were the geometry of the beams (2000x125x250)mm as well as the test set up. A series of trials was made to obtain a suitable mix proportioning of SCC based on “Nan Su et al” method. The cracking, deflection and ultimate failure behaviour were experimentally studied. The available theoretical formulae proposed by Suji et al and Samir for FRC beams with conventional vibrated concrete beams were examined for the case of SFRSCC beams with respect to load deflection behaviour, ultimate moment, deflection and width of crack at service loads. A simplified effective moment of inertia function is proposed for the estimation of deflections of SFRSCC beams at all stages of loading. The results are presented and discussed.

Keywords:

Beams , Flexure , Self-Compacting , Fibre Reinforced