Meso-level Mechanics Analysis On Bending Resistance Properties Of Hybrid Fiber Reinforced Concrete

Large amount of literatures about hybrid fiber concrete (including ordinary hybrid fiber concrete, layered hybrid fiber concrete and different geometric dimension of hybrid fiber concrete) have been collected and reviewed in this paper. research situation of hybrid fiber concrete were then be understood. In this paper, by using numerical analysis software RFPA2D (Realistic Failure Process Analysis) owned by Professor Tang Chunan in Dalian University of Technology to simulate the flexural performance of the hybrid fiber concrete. Based on the existing knowledge of mesoscopic structure of concrete material, t hybrid fiber concrete is assumped to be a two-phase composite material composed of fiber and concrete (the interface is assumed to be an ideal one). In order to consider inhomogeneity of material properties, various components are assigned according to the given Weibull distribution. Elastic damage constitutive relationship could be satisfied within mesoscopic element.Hence, two-dimensional hybrid fiber concrete model could be established. By changing fiber's content, layouts, length in concret, the law of crack growth in the failure process, the final crack patterns, the trend of the load-displacement curve, temporal and spatial distribution of acoustic emission, bending toughness and bending strength, have been analyzed to reveal the failure law and the strengthening mechanism of hybrid fiber concrete. The major contents are listed as following:(1) Establish the numerical models with different incorporation ratios of steel-polypropylene fiber reinforced concrete and carbon–steel fiber reinforced concrete.Through numerical tests of different incorporation ratios, the influence of the different fiber type and the different dosage on concrete bending strength and deformation properties were discussed. By comparing the numerical results and existing experimental results in reviewed liteature,and some significant conclusions can be drawn.(2) Establish the numerical model of layered hybrid fiber reinforced concrete (decorate steel fiber about 20cm , decorate polypropylene fiber in intermediate place). The numerical simulation of whole processes of crack initiation, growth, running through to finally unstable have been obtained for layered hybrid fiber reinforced concrete. with same fiber dosage, the layered hybrid fiber reinforced concrete can improve the strength and toughness better than the other. (3) Establish numerical models ofhybrid fiber reinforced concrete with different geometric sized. The influence of length/short proportion on specimen peak load, flexural toughness, strain etc. have been studied. Conclusions can drawn that when long, short fibers are in the proportion between 2:1 ~ 1:1, performance of hybrid fiber is the best.