Experimental Study On Bond Slip Behavior Of Shaped Steel Reactive Powder Concrete

Steel-reinforced concrete structure is a kind of composite structure with excellent performance,the structure is composed of steel sections placed in the reinforced concrete structure,thus,it has the common advantages of reinforced concrete structure and steel structure,large bearing capacity and stiffness of the structure and excellent seismic performance.In practical engineering applications,high-rise buildings,super high-rise buildings and long-span structures are all SRC structures.With the progress and development of the society,the traditional concrete has been unable to meet this excellent structural form,therefore,in this paper,reactive powder concrete is used in SRC structure instead of ordinary concrete to form a composite structure of shaped steel reactive powder concrete.It not only has the advantages of high bearing capacity,large stiffness and excellent seismic performance of SRC structure,but also makes up for the shortcomings of traditional concrete caused by the poor crack resistance and fire resistance.In order to popularize the application of SRC composite structure in engineering,it is very important to study the bond slip performance of SRC.It is closely related to the calculation of stress distribution between structural interfaces,structural bearing capacity and interfacial bond strength.The bond slip behavior of SRC composite structure is also the key to the design calculation theory of this structure.In this paper,14 SRC specimens are designed,and the push test is carried out on these 14 specimens,the bond-slip behavior of steel-shaped reactive powder concrete was studied.The five different influencing factors in the experiment are as follows:Reactive powder concrete cube compressive strength,the protective layer thickness of reactive powder concrete,the embedded length of section steel,the ratio of transverse stirrup and the bonding position;This experimental study carried out the following specific work:(1)By trial and error,observe the crack development and failure mode of the specimen,summarize three different main modes of damage.The slip between the loading end and the free end was measured by the displacement meter placed at the loading end and the free end,the load-slip curves of the loading end and free end are obtained and the variation rule of the curves is summarized.By pasting resistance strain gauges on the flange and web of the section steel,the strain distribution of the section steel at different stages and under different loads is obtained.(2)The characteristic bond strength of steel active powder concrete was analyzed and studied,according to the experimental data,the effects of five different reference factors on the characteristic bond strength were analyzed,the relationship between characteristic bond strength and influencing factors is obtained respectively,and the calculation formula of characteristic bond strength is fitted.(3)Further study of the experimental data,in accordance with the definition of characteristic slip value of section steel ordinary concrete,to obtain the characteristic slip value in this experiment,and it is analyzed statistically.Through the processing of the loading side test data,the average bond stress-slip curve is obtained.And then the curve type,to establish τ-s curve constitutive model,and it is described by mathematical expression.(4)According to the test results,the bond stress is different at different locations,the calculation formula of strain along embedded length is obtained by fitting the strain distribution law of section steel mentioned above,the final bond-slip constitutive relation is obtained by further analysis.