Analytical and Experimental Study on Steel Fiber Reinforced Concrete Corbel

Abstract

The research program for this thesis studies the benefits of using steel fiber in rein- forced concrete corbel. By using Steel Fiber Reinforced Concrete corbel, some of the difficulties associated with it's construction can be overcome and a greater seismic strength can be provided. Use of steel fiber provides ductility to the section, it reduces crack width and also increases the ultimate shear capacity of the section. Several points emerge from a study of the behavior of corbel under vertical load that has been taken into account to develop a method of design. The main factors inuencing the behavior of corbel section under ideal condition are av/d(Shear span/depth) ratio , Percentage of main reinforcement , Concrete strength and Fiber percentage in the section. Various guidelines as provided by different codes i.e. IS-456, ACI-318 and EC-2 were studied and comparison between those guidelines was done. It was observed that the information for designing the section with use of steel fiber was lacking or has not been incorporated in the guidelines. Thus, An analytical method was proposed based on Truss Analogy for estimating the ultimate load bearing capacity of corbel specimen under vertical loads which takes into account various parameters like bond stress, fiber stress, fiber length/diameter ratio(Aspect ratio). A comparison with 51 test results reported in the literature is made and proposed theory is also verified with experimental work. Experimental work comprises of Four corbel specimen constructed without addition of steel fiber in order to reflect current building code , Four steel fiber in reinforced concrete corbel were constructed with a fiber percentage of 0.5 % while Four steel fiber in reinforced concrete corbel were constructed with a fiber percentage of 1.0 % by varying the percentage of main tensile reinforcement as 0.8 % for 6 specimen and 1.2% for remaining 6 specimen. Xorex steel fibers with a length of 30-mm, a diameter of 0.50-mm and an aspect ratio of 60 were used. Design charts for reinforced concrete corbel for various codes were discussed and same charts were modified for steel fiber reinforced concrete corbel. with the use of modification made in chart one can easily derive the increase in strength of section with increase in percentage of steel fiber. The modification factor is found based on Aspect ratio and percentage of steel fiber. .