Experimental and theoretical investigation of the shear resistance of steel fibre reinforced prestressed concrete X-beams, part II: theoretical analysis and comparison with experiments

This is the second part of two papers on the experi- mental (Part I)and theoretical (Part II)resistance of steel fibre reinforced precast concrete beams. High strength steel wire,and thin amorphous metal fibres have been introduced into prestressed concrete X beams in order to study their behaviour under shear loads. Experimental tests have determined shear strengths at the ultimate and cracking loads,and shown increased ductility with up to 2 %fibre content.From these tests two differ- ent methods are proposed for predicting the ultimate shear capacity - these are the fibre supplement additive method,and the modified FRC principal tensile stress method.The principal tensile strength of the fibre rein- forced concrete is given as a function of compressive strength and fibre volume.The mean value of the ratio of the calculated to the test strength is 0.89 without partial safety factors,and,being conservative,is proposed for use in design.A calculation model is presented.