Numerical Simulation Of Flexural Toughness Test Of Hybrid Fiber Reinforced Concrete Slab With Low Volume Fraction

The toughness of fiber reinforced concrete is an important indicator to fully reflect the intrinsic quality.The flexural toughness of hybrid fiber reinforced concrete can be more clearly reflect the hybrid fiber toughening effect, the motherland and foreign scholars widely will be the main index of flexural toughness as a measure of toughness of hybrid fiber reinforced concrete. At present, the numerical simulation is one of the important methods for studying the flexural toughness of fiber reinforced concrete.In this paper, referenced Standard Test Methods for Fiber Reinforced Concrete(CECS 13-2009), the numerical model of hybrid fiber reinforced concrete circular and square slab was established by using Link180 element and SOLID65 element of the ANSYS. By fixed step loading method, and with the same boundary conditions of the actual test, the paper achieved simulation from micro-cracks initiation, propagation and coalescence process of the hybrid fiber reinforced concrete slab specimens. What’s more, there has been related to the load- deflection curve, crack propagation figure and the stress nephogram. According to the simulation results, this paper analyzed the effect of fiber content, fiber types on concrete slab flexural toughness, and the hybrid effect of steel fiber and polypropylene fiber.The simulation results show that:(1)The polypropylene fiber was not significantly on failure mode, concrete strength of concrete matrix, but it could improve the toughness of concrete slabs and improve the deformation capacity; incorporation of steel fiber could slow down the crack of concrete matrix, extend the crack propagation path, and improve the flexural toughness of concrete matrix.(2)In the early load simulation, effects of hybrid fiber on the load-deflection curve was not significantly, more than the ultimate flexural load of specimens, the loaddeflection curve was roughly same, but the full extent was different. And S5(steel fiber A content was 1.2%, polypropylene fiber content was 0.11%) groups, P4(steel fiber content was 1.2%, polypropylene fiber content was 0.11%)groups showed the best flexural toughness.(3)When the hybrid fiber volume content was the same, ultimate flexural strength of the circular slab with ultrashort microfilament steel fibers was higher 15.5% ~ 17.8% than mixing multiple anchor steel fiber, and energy absorption value increased by 7.2% ~ 77.2%.(4)The energy absorption value of hybrid fiber reinforced concrete square slab and the volume content of the hybrid fiber were positively correlated, when the center deflection of square slab reached 25 mm, the energy absorption value of P4 groups(steel fiber content was 1.2%, polypropylene fiber content was 0.11%)than the P2 groups(steel fiber content was 0.8%, polypropylene fiber content was 0%), P3 groups(steel fiber content was 0.8%, polypropylene fiber content was 0.11%) were increased by 94.6%,83%.