| The application of steel fiber reinforced concrete has always been a hot topic in the study of building structures.Subway stations and shield sections will use a lot of reinforced concrete.However,there are many drawbacks such as poor ductility and durability to be improved in the underground structure.Therefore,the introduction of fiber reinforced concrete can improve the toughness and durability of the structure and reduce the amount of steel to a certain extent.Therefore,the application of steel fiber reinforced concrete Sexual research there is a very broad prospect.Based on the scientific research project of shield concrete test section,this paper studies the applicability of fiber reinforced concrete segments by analyzing 63 cubic cubes,36 notched beams,28 girders,8 pieces of segment of experimental data for statistical analysis,using theoretical derivation and numerical simulation and other methods to study.For this purpose,the following work was carried out:In this paper,the mechanism of fiber reinforced concrete is discussed,and a model of damaged constitutive fiber is suitable for analysis.The design method of limit state is introduced,which is used as the whole analysis method.The basic mechanical properties experiment was carried out,and the strength and fiber distribution were analyzed.Based on the analysis of six different fiber ratios,different fiber types and different concrete strength,the residual strength of the notched beam was analyzed.The results show that the C50-5D-40kg fiber concrete notched beam has the same load capacity,and the different ratio has different stress softening or hardening characteristics.The experimental analysis of 8 cases of fiber reinforced concrete segments,28 pieces of fiber reinforced concrete beams(14 pieces of tendons and 14 pieces of non-tendons)were carried out by using self-designed experimental loading platform.The experimental results show that:1)In this experiment,the addition of steel bars can increase the maximum bending moment of the structure by 46%and greatly enhance the ductility.2)The design of eccentricity has great influence on the bearing capacity of the ultimate state of the structure.The new design ideas,in a reasonable combination of load can try to use the structure without ribs.4,L4,L5,L6,L4 four groups of a total of 16 with a beam of experimental results,drawing the ultimate carrying capacity envelope,in addition to steel fiber L7,L4,L5,L6 carrying capacity are better than the design value,The best performance of the experiment is 4D steel fiber content of 20～30kg/m3,the matrix selection C50 concrete;normal use of the introduction of the concept of crack width safety factor,compared to "mixed" and the German standard calculation,Compared with the experimental data of crack without steel fiber L7,it is proved that the crack resistance of concrete beam is basically doubled after adding steel fiber.When the fiber content is 4D,the width of the crack is reduced by 2.65 times.When the fiber content is 25kg and the fiber type is 4D,the crack width is reduced by 1.09 times,the fiber content is 25kg and the fiber type is 5D.And the deflection is reduced by 2 times.ABAQUS is used to simulate the deflection and fracture model of steel fiber reinforced concrete,and the actual experimental results are confirmed.According to the experimental data,the stress state of the beam is analyzed,and the calculation formula of the allowable opening cracking and the non-allowable cracking of the section is deduced.The height of the compression zone is determined and combined with The residual strength of the toughness experiment is compared with the technical specification of the fiber concrete structure,and the limit state strength formula of the fiber concrete is put forward from another angle.From the angle of the energy method of the mountain tunnel,the strain energy is obtained by integrating the load-deflection curve of the incision beam,To guide the design of shield segments. |
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