Ductility and Deformation Performance of Hybrid Fiber Reinforced High Performance Concrete Shear Deep Beams

The shear tests were made on 18 different groups of deep beams with steel fiber and polypropylene fiber according to the orthogonal experimental design. For comparison, 2 groups of high performance concrete deep beams without fiber were conducted. Shear ductility and deformation performance of deep beams were analyzed quantitatively. Results illuminate that failure mode of high performance concrete shear deep beam is splitting failure, while hybrid fiber reinforced HPC shear deep beam has two failure modes (splitting failure and diagonal compression failure). The mixing of hybrid fiber makes rigidity of HPC deep beam increase obviously, the strain of web horizontal reinforcement and web vertical reinforcement decrease significantly. The catastrophe of strain of cracked concrete is also obviously smaller and the descending step of loaddeflection curve is flatter when adding hybrid fiber. Hybrid fiber can greatly increase shear ductility of deep beams and shear ductility is at the most increased by 40.7% whereas it can not change the brittleness of shear damage radically. The volume fraction of steel fiber plays the most important role in shear ductility whereas the shape of steel fiber has minimum effect among analyzed six factors.