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In order to study the shear resistance and design method of hybrid fiber (steel fiber and polypropylene fiber) reinforced high performance concrete deep beams, the shear tests were conducted according to the orthogonal experimental design. The contributory factors such as the characteristic parameters of steel fiber (types, volume fraction, aspect ratio), the volume fraction of polypropylene fiber, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement were analyzed. Results illuminate that shear failure mode of hybrid fiber reinforced HPC deep beams are splitting failure and diagonal compression failure. Hybrid fiber can notably increase the diagonal cracking strength and shear strength of HPC deep beams. The diagonal cracking strength is increased by 5.6%~83.8% while the shear strength is increased by15.6%~35.2%. A formula to calculate the shear resistance of hybrid fiber reinforced HPC deep beams is put forward based on spatial strut-and-tie mode and splitting failure. Meantime test verification is carried out and the calculated results are satisfied.

18 different groups of hybrid fiber (steel fiber and polypropylene fiber) reinforced HPC deep beams and 2 groups of HPC deep beams without fiber were made. The shear tests under the static load and the numerical simulation by ABAQUS were conducted. Good agreement are found between test results and simulation results.The results of finite element analysis indicate that with the increment of reinforcement ratio, the shear capacity of hybrid fiber reinforced HPC deep beams increases, but quite limited. The variation of shear capacity of hybrid fiber reinforced HPC deep beams is not obvious as the shear-span ratio changes (when ) . The increment of span-depth ratio can improve the shear capacity of hybrid fiber reinforced HPC deep beams, but only with small amplitude. All these regularities are similar to those of ordinary reinforced concrete deep beams.

The shear behavior of 18 different groups of hybrid fiber (steel fiber and polypropylene fiber) reinforced HPC deep beams and 2 groups of HPC deep beams without fiber were discussed through experimental study and nonlinear finite element analysis. The shear tests were made under the static load and the finite element analysis software ABAQUS was used in numerical simulation. Results illuminate that hybrid fiber can significantly increase the diagonal cracking load and the ultimate shear load of deep beams although it can not change the brittleness of shear damage. Good agreement are found between test results and simulative results, including failure mode of hybrid fiber reinforced HPC deep beams, load-displacement curves, stress distribution of steel bars and concrete, etc.

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.

In order to investigate the effect of steel fiber and polypropylene fiber on shear behavior of HPC deep beams, the shear tests were conducted on 18 different groups of deep beams with steel fiber and polypropylene fiber and 2 groups of HPC deep beams without fiber according to the orthogonal experiment. 6 factors, including the shape of steel fiber, the volume fraction of steel fiber, the aspect ratio of steel fiber, the volume fraction of polypropylene fiber, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement, were compared by direct-viewing analysis. Results illuminate that hybrid fibers greatly increase the diagonal cracking strength and shear strength of HPC deep beams. The aspect ratio of steel fiber plays the most important role in diagonal cracking strength whereas the ratio of web vertical reinforcement has minimum effect. Meanwhile the ratio of web horizontal reinforcement plays the most important role in shear strength whereas the volume fraction of polypropylene fiber has minimum effect. An anti-cracking capacity for inclined section calculation formula and a shear bearing capacity calculation formula for hybrid fiber reinforced HPC deep beams are put forward based on current code. Meantime test verification is carried out and the calculated results are satisfied.