A STUDY OF CONFINED STEEL FIBER REINFORCED CONCRETE IN THE PLASTIC HINGING REGIONS OF RC BEAMS

The structures subjected to earthquake, nuclear blast forces etc., demand more ductility to absorb strain energy. The limited ductility of concrete also affects the performance of structure under static loads. Almost all codes of practice around the world stipulate only the ductile failure of structural components, which is the major drawback of the over reinforced concrete beams. It is well known that the confinement of concrete increases the compressive strength and ductility, the latter to a larger degree. Such concrete is called ductile concrete. The limitations on the spacing of stirrups will restrict the improvement in the ductility of concrete confined by the stirrups. The use of Steel Fiber Reinforced Concrete along with the stirrup confinement in the possible plastic hinging regions may enhance the overall ductility of concrete structures. Such engineered application of SFRC may be termed as Engineered Steel Fiber Reinforced Concrete (ESFRC). This paper presents an experimental investigation to study the behaviour of ESFRC by varying the volume percentage content of steel fiber. Four rectangular reinforced concrete beams, with the steel fiber reinforced concrete in critical sections along with the stirrup confinement, have been tested. The findings of the investigation indicate that up to about 80 percent of ultimate strength, the behaviour of ESFRC beams was similar to that of beams with rectangular tie confinement. The effect of the steel fiber was felt prominently beyond the post ultimate stage. The ductility is increased due to increase in percentage of fiber content.