Softened Truss Model Theory for the Analysis of Fibre Reinforced Concrete Deep Beams and Corbels - E

21 Softened Truss Model Theory for the Analysis of Fibre Reinforced Concrete Deep Beams and Corbels S. A. Al-Ta’an, Professor N. S. H. Al-Husaini, Assistant lecturer Department of Civil Engineering, Dept. of Building and Construction, Mosul University, IRAQ Technical Engineering College, Mosul Corresponding author, S. A. Al-Ta’an, Email: saad.altaan@yahoo.com Abstract Reinforced concrete members may be subjected to axial load, bending moment, shear and torsion. However the behaviour of these members under shear or combined shear and torsion is a complex phenomenon. In this study the softened truss model theory is applied for the analysis of fibre reinforced concrete deep beams and corbels. The theory is more promising than the strut and tie model which satisfies the equilibrium conditions and to some extent materials constitutive relationships. While this theory, considers the equilibrium, compatibility, materials constitutive relationships and the degrading effect of the diagonal tension cracks on the compressive strength of cracked reinforced concrete element when subjected to biaxial compression-tension stresses. The previously developed algorithms for the analysis were modified by incorporating the effect of short discrete steel fibres on the behaviour and strength of concrete subjected to shear. Fibre reinforced concrete deep beams and corbels were analyzed using the adopted algorithm and materials constitutive relationships. The predicted effects of the shear span / depth ratio, volume fraction of steel fibres and the longitudinal steel ratio on the shear strength of fibre reinforced concrete deep beams and corbels showed good agreement with published experimental results.