Experimental Study And Finite Element Analysis On Shear Behavior Of Steel Fiber Reinforced High-strength Concrete Full-scale Corbel

As a vertical load-bearing component providing cantilever support,reinforced concrete corbel is widely used in industrial buildings,roads and bridges,hydraulic structures,power plants and other structures.With the development of society,the practical engineering puts forward higher requirements for the crack resistance and bearing capacity of reinforced concrete corbel.In theory,it is one of the effective ways to make reinforced concrete corbel with steel fiber reinforced high strength concrete.However,due to the nonlinear characteristics of concrete materials and the complexity of the shear mechanism of the corbel,the actual shear performance and the calculation method of shear capacity of the steel fiber reinforced high-strength concrete corbel need to be further explored and studied.For a long time,scholars at home and abroad have done a lot of research on the shear performance of the corbel by combining theoretical analysis and experimental research,and obtained some semi empirical and semi theoretical calculation formulas.However,most of the existing researches focus on the common concrete corbel,whether these formulas are applicable to the actual steel fiber reinforced high-strength concrete corbel with large section size remains to be verified.However,most of the existing researches focus on the common concrete corbel,whether these formulas are applicable to the actual steel fiber reinforced high-strength concrete corbel with large section size remains to be verified.In this paper,with the support of National Natural Science Foundation of China(U1404526),the shear behavior of full-scale corbel of steel fiber reinforced high-strength concrete with shear span ratio of about 0.3 is studied.The influence of shear span ratio,main reinforcement ratio,hooping ratio and steel fiber content on the shear performance of corbel is studied by the method of static load test and nonlinear finite element analysis.The main research results of this paper are asfollows:(1)The shear span ratio has a significant effect on the failure mode of the corbel.The failure mode of the corbel is oblique shear failure when the shear span ratio is equal to 0.2.With the increase of the shear span ratio,the failure mode of the corbel is transformed from oblique shear failure to oblique crush failure when the shear span ratio is greater than 0.3.(2)Shear span ratio and steel fiber content have great influence on bearing capacity of normal section.The bearing capacity of oblique section is mainly affected by shear span ratio,main reinforcement ratio and stirrup reinforcement ratio.Steel fiber can effectively control the crack width of high-strength concrete corbel,but has little effect on the oblique section bearing capacity of full-scale corbel.(3)Shear span ratio,main reinforcement ratio and hooping ratio have great influence on the ultimate bearing capacity of full-scale corbel.Reducing shear span ratio and increasing stirrup ratio can increase the actual compressive strength of concrete in the inclined compression zone.Increasing the main reinforcement ratio is equivalent to directly improving the strength of the tie rod in the Strut-and-Tie model.When the main reinforcement ratio is too high,the ultimate bearing capacity of the corbel is mainly determined by the concrete strength in the inclined compression zone.(4)The addition of steel fiber can improve the ductility of corbel slightly,but it does not change the brittle failure characteristics of high-strength concrete corbel.(5)In this paper,the shear transfer mechanism of full-scale corbel is analyzed.The prediction formula of the ultimate bearing capacity of full-scale corbel considering the combination of vertical bearing capacity of SFRC in shear compression zone,bolt capacity of steel bar and shear capacity of shear resistant steel bar.The results calculated by the prediction formula are in accordance with the test results.(6)Through the nonlinear finite element analysis of the corbel structure,the distribution of stress and strain in the corbel is obtained.It provides a numerical support for the calculation of the bearing capacity of the corbel structure using the Strut-and-Tie model.Combined with the test results,this paper confirms the shear transfer mechanism of the corbel structure,and further verifies the applicability of the calculation method of the shear bearing capacity of the corbel.