Study On Bond Slip Behavior Of Section Steel And Reactive Powder Concrete At Room Temperature

In order to improve the utilization of resources and improve the construction environment,the state needs to develop new building materials.In engineering construction,the most commonly used material is concrete.In the current new high-strength concrete materials,reactive powder concrete(RPC)is a representative one.Compared with the common concrete in engineering,RPC has higher compressive strength,tensile strength,and stronger durability in the same environment.It has a broad development in the future engineering construction and reinforcement View.Reactive powder concrete(RPC)combined with section steel inherits the characteristics of high ductility and stiffness of ordinary steel reinforced concrete structure,and has better fire and corrosion resistance.The bond slip behavior between profile steel and reactive powder concrete interface is an important research topic,which is closely related to the stiffness of the structure,the shear distribution between the interfaces and the calculation of bond strength.It has an important reference value for the preparation and supplement of technical specifications related to structural design.In this paper,seven rectangular columns of reactive powder concrete are designed and poured,and the push-out test is carried out at room temperature,which is used to study the viscous slip between the steel and reactive powder concrete.Among them,the factors considered by five specimens are: the thickness of reactive powder concrete protective layer,stirrup ratio,etc.;the other two specimens are divided into two groups to compare the contribution of the web and flange of the profile steel to the bond strength by applying separators to different positions of the profile steel.Strain gauges are arranged on the surface of longitudinal bars,stirrups and the flange of the upper and lower ends of the section steel.By analyzing the strain values at different measuring points of the test piece,the law of stress change at multiple positions in the bond area is obtained.The load slip curve(p-s curve)ofthe interface between steel and concrete is obtained by means of the press and the displacement meter at the upper and lower ends of the specimen.According to the ratio of load to the surface area of steel,the stress(τ)can be obtained,and then the bond strength displacement curve(τ-s curve)between steel and reactive powder concrete can be calculated.Based on the observation of experimental phenomena,the fracture morphology and failure mode are summarized,and two simplified fracture model diagrams are obtained.Because the interface bonding is affected by many factors,it is necessary to consider the correlation of various factors when calculating the total bond strength of steel and reactive powder concrete at room temperature.In order to study the change rule of different factors on the bond strength of reactive powder concrete,the calculation method of the bond strength of the interface is obtained.In this paper,the thickness of reactive powder concrete cover and stirrup ratio are considered.The data of each factor are analyzed,and the expression of characteristic average bond strength under the influence of each factor is fitted.For the test piece of this push out test,the ABAQUS finite element analysis software is used to input the cross-section size and mechanical performance index of the composite column,establish the analysis model,and simulate the interface adhesion between the medium-sized steel reactive powder concrete in the whole push out process.The slip phenomenon simulated by the software is basically consistent with the phenomenon of the test result.