Experimental Study On Shearing Behaviour Of Fiber Reinforced High Strength Concrete Beams With Stirrup

In this paper, results of an experimental and analytical investigation on shear behavior of 22 steel fiber reinforced high-strength concrete beams under even loads are presented. The study explores the effects of concrete strength, contents of stirrup, ratio by volume of steel fiber and types of steel fibers on shear behavior of beams. The tests show:1. For high strength concrete, steel fiber cannot drastically change the mechanism of the beam's shearing behavior, so its failure pattern is still within the typical ones: shear-compress , shear-tension and so on.2. The steel fiber cannot obviously improve the loads corresponding to the first inclined cracks. But after the appearance of cracks, steel fiber has significant effect on restriction of the extension of the crack's width. The process of the fracture and the crack shape show the following three characters: "late, thin and thick".3. To some extent, steel fiber can improve the beam's strength capacity, and the enhancement of ultimate strength of steel fiber beams with high strength concrete is greater than that with plain strength concrete because of the better bond between the high strength concrete and steel fibers.According to tests and researches acquired at home and abroad, and also consistent with the Code For Concrete Structures Design, the formulae for shear capacity of high strength steel fiber reinforced concrete beams under even loads are derived. Good consistency is achieved between the calculated result and the test one. For each specimen, approximate reliability of the results given by the two equations is presented.The following conclusions can also be drawn according to the tests: Given the same contents but different types of steel fiber, the enhancement of shear capacity of beams shows little difference. Based on this, a unified formula for the loads subentry considering concrete and steel fiber is given.In addition, certain extent of rupture of steel fiber is found in the high strength concrete beams. It is suggested that for high strength concrete, the problem of rupture of steel fiber should be considered.