| Reactive powder concrete (RPC) is one kind of cement-based composite material with many excellent performances such as high strength, high toughness, high durability and so on. GFRP (Glass Fiber Reinforced Polymer) bar is one kind of composite material with many excellent performances such as light weight, high strength, corrosion resistance and so on. As two kinds of new materials, RPC and GFRP bars used in civil engineering can play the role in reducing weight, increasing carrying capacity and durability with their excellent performances, and both have good prospects. Beams and slabs formed by the organic combination of these two types of material can make both excellent performances into full play and have certain prospects.Considering the deficiency on RPC preparation technology, based on summarizing the research results at home and abroad, two groups of mix ratio test are carried out, mixed without steel fiber in the first group and mixed with steel fiber in the second group. Through the analysis of test results and factors, optimal ratio of RPC without steel fiber and optimal ratio of RPC with steel fiber are obtained respectively.Considering the faultiness of compressive and tensile stress-strain curves of RPC, test researches on basic mechanical properties of RPC without steel fiber and RPC with steel fiber are carried out respectively. In the test of basic mechanical properties of RPC without steel fiber, cube compressive strength, axial compressive strength, strain corresponding to the peak stress, elastic modulus and poisson ratio at different ages are obtained. The ascending part of compressive stress-strain curve is obtained and the equation of the ascending part of stress-strain relation is proposed by modifying the existed formula by introducing the coefficient. Combination of the test of steel reinforced RPC beams, by assuming that the declining part of stress-strain curve of RPC used in the beams is straight and based on the measured flexural carrying capacity and the measured compressive strain of RPC on the compressive ultimate fiber in bending region, the equation of declining part of stress-strain relation of RPC without steel fiber used in calculation of flexural carrying capacity of this kind of flexural component is anti-deduced. So the whole curve equation of compressive stress-strain relationship of RPC without steel fiber used in calculation of flexural carrying capacity of this kind of flexural component is obtained. In the test of basic mechanical properties of RPC with steel fiber, axial compressive test and axial tensile test are carried out. The axial compressive strength, axial tensile strength, strain corresponding to the peak stress and elastic modulus are obtained. And the equations of compressive and tensile stress-strain relations are proposed by selecting of models of compressive and tensile stress-strain relationships and fitting the models and measured compressive and tensile stress-strain curves.To study the mechanical properties of steel reinforced RPC(without steel fiber)beams and anti-deduce the declining part of compressive stress-strain relation of RPC without steel fiber used in calculation of flexural carrying capacity of this kind of flexural component, mechanical properties test of 5 steel reinforced RPC beams is carried out. The mechanical properties such as flexural carrying capacity, stiffness and cracks are studied by one-third point loads experiment. The flexural carrying capacity calculation method, stiffness and cracks calculation methods of steel reinforced RPC beams are given.To study the mechanical properties of GFRP bars reinforced RPC (with steel fiber) beams, mechanical properties test of 8 GFRP bars reinforced RPC beams is carried out. The mechanical properties such as cracking loads, flexural carrying capacity, stiffness and cracks are studied by one-third point loads experiment. Based on the tensile stress-strain relationship of RPC, the calculation method for influence coefficient of section plastic resistance moment and the calculation method for cross-sectional cracking moment are proposed in combination with test data. Tension failure, limit failure and compression failure, the three types of failure mode of GFRP bars reinforced RPC beams are analyzed and the formula of limit reinforcement ratio is given which considers the influence of tensile stress of RPC in the tension zone. The calculation methods of compression failure and tension failure are given respectively. Based on mechanical characteristics and test results of GFRP bars reinforced RPC beams, the calculation methods for stiff and cracks of GFRP bars reinforced RPC beams are deduced which are in convergence with"code for design of concrete structures"(GB50010-2002). Because the compressive strain on the compressive ultimate fiber of RPC beams with steel fiber is about 5500με, the cracking strain on the tensile ultimate fiber is about 750μεand the ultimate tensile strain of GFRP bars is about 20000με, it is a relatively long process from the tensile zone of beam going into plasticity to failure. To study the plastic properties of RPC continuous beams reinforced with GFRP bars, the calculation programs for moment redistribution coefficients are prepared by using nonlinear analysis methods. By comparing the test results of existed FRP bars reinforced concrete continuous beams with simulation results, the accuracy of the calculation programs is verified. Then 18 simulated GFRP bars reinforced RPC continuous beams are selected. Through the nonlinear analysis of simulated beams, moment redistribution coefficients under mid-span concentrated loads, one-third point loads and uniformly distributed loads are obtained respectively, then the formula of moment redistribution coefficients which take reinforcement ratio of mid-span and middle support as variables under the three types of loads are proposed respectively by fitting moment redistribution coefficients and factors. |
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