FLEXURAL STRESS BLOCK FOR HYBRID FIBRE REINFORCED CONCRETE MEMBERS

Abstract

There is increase in fiber use in concrete for the structural applications from last few decades. There is demand of providing cost effective technique with this innovative material while offering improved structural properties. In this paper the simple flexural stress block is converted for hybrid fiber reinforced concrete.By using the standard experimental study of HyFRC, from the same model we found fiber index for HyFRC. Which can be used for HyFRC member design. The flexural model takes into consideration the fiber orientation with respect to loading axis and fiber distribution at the cracked section. The model is Elastic and perfect plastic model for compression and elastic constant post peak response of HyFRC in tension is considered. Hence a simplified flexural stress block for HyFRC to find the flexural capacity is proposed. The standard experimental study of HyFRC has been done. This experimental study is used for finding the fiber index for the HyFRC. The standard test on HyFRC in compression and flexure are carried out. The tests are conducted using constant aspect ratio (75) and volume fraction (1.25% and 1.75%) by varying steel fiber content and polypropylene fiber content. The fiber index is related with fiber parameters (Aspect ratio, Volume fraction) and concrete compressive strength. The compression tests are conducted on cubes and flexural test on prismatic beams. The analytical results are cross checked with experimental results. A design chart is also proposed to find the fiber parameters during flexural design of HyFRC rectangular member.