STRENGTH AND DEFORMATION CHARACTERISTICS OF FIBER REINFORCED CONCRETE IN FLEXURE

Abstract

The load-deflection behavior is fundamental for the evaluation of strength and deformation characteristics of flexural members. These may be include determining the first crack load, ultimate load carrying capacity and the ductility of the member as a whole together with the mode of failure. Established analytical procedures based on moment-curvature characteristics or on finite element analysis are available for determining the complete load-deflection behavior of non-fibrous reinforced concrete sections. However relatively few studies have addressed the issue of analytically determining the load-deflection response of fibrous reinforced concrete flexural members. The efforts in the present investigation, unlike many of the past investigation, have been directed towards the theoretical evaluation of the strength and deformation characteristics of steel fibrous reinforced concrete section. Emphasis has been laid on; predicting the load-deflection behavior of fiber reinforced concrete beams using the analytical methods. The proposed method is based on the moment-curvature relationship approach which takes into account the fiber-matrix interfacial bond stress, fiber stress, fiber aspect ratio and volume fraction of the fibers. In essence, the moment capacity of the fibrous concrete section is evaluated independently and then added to the moment capacity furnished by reinforced concrete. If the moment-curvature relationship of a section is known, the bending moments, shears, axial forces and deflections of fibrous reinforced concrete members at any stage of loading from zero to ultimate load can be determined analytically using the conditions of static equilibrium and geometric compatibility. Starting from this premise the present study has been carried out to determine theoretically the load-deflection behavior of steel fiber reinforced concrete beams. The theoretical evaluation of the load-deflection response has been carried out for RCC beams containing straight, crimped, hooked end, and duoformed fibers, for various volume fractions (0.5, 1 and 1.22 percent) and aspect ratios (60, 75 and 100). The theoretically obtained results have been compared with experimental results reported in literature and a good agreement has been obtained between the two.