Axial Behavior Of Corrugated Steel Tubular Steel Reinforced Concrete Short Columns

Concrete-filled steel tube(CFST)and confined concrete-filled steel tube(CCFST)have been widely used at home and abroad because of their advantages of high bearing capacity,good seismic performance,convenient construction and superior fire resistance.In recent years,with the development of their application fields,The external environment of steel pipe is becoming more and more complex,the corrosion problem of structure becomes more and more serious,and the existing anticorrosion treatment measures also have many problems,such as high maintenance cost,large maintenance workload,high difficulty in construction operation and so on.In order to solve the corrosion problem of the structure,reduce the difficulty of the anticorrosion measures and maintain the superior mechanical properties of the structure,this paper presents a new type of composite member filled with concrete in galvanized corrugated steel pipe and equipped with a steel section inside,which is called corrugated steel tubular steel reinforced concrete.Galvanized corrugated steel pipe is directly contact with the external environment,under the protection of galvanized layer,the component has good anticorrosion ability,and the corrugated steel pipe can also provide enough restraint to the inner core concrete and steel section.the axial compressive mechanical properties of corrugated steel tubular reinforced concrete short columns are studied experimentally and analyzed by finite element method.The main contents are as follows:1.The tests of 9 short columns under axial compression have been completed,include 1 short steel reinforced concrete column(SRC),1 short steel reinforced concrete column confined by steel tube(TSRC-S),1 corrugated steel tubular steel reinforced concrete columns with gaps(TSRC-CSP with gaps),2 corrugated steel tubular steel reinforced concrete columns(TSRC-CSP),2 columns with simple combination of steel section and concrete(S+C),2 steel reinforced concrete columns confined by steel tube and reinforcement cage(TSRC-SS).In the experiment,the failure modes of above members are observed,and the integral deformation of specimens under axial compression load and the strain change of external steel pipe are tested.The distribution of stress along the height of ordinary steel tube and corrugated steel pipe is discussed by elastic-plastic stress analysis.The results show that the stress of corrugated steel pipe is cosine distribution along the direction of column height,and corrugated steel pipe can provide enough restraint for the core concrete and steel section.Corrugated steel pipe with gaps do not affect the axial compression mechanical properties of the members.2.The finite element model of corrugated steel tubular steel reinforced short columns under axial compression is established by using the finite element software.The model is verified by experimental data.Based on the established finite element model,the bond between corrugated steel pipe and concrete is discussed.The stress distribution of external corrugated steel pipe is verified and the influence of corrugated form,friction coefficient and spiral angle on axial compressive mechanical properties of corrugated steel tubular steel reinforced concrete short column is analyzed.The results show that the corrugated steel pipe is close to the inner concrete,and the influence of the spiral angle of the corrugated steel pipe can be neglected.The ratio of wave height and wave distance of corrugated steel pipe is advised to be 0.2.3.Based on the established finite element model,the key parameters which affect the axial bearing capacity of steel members are analyzed,such as concrete strength,steel yield strength of corrugated steel pipe,ratio of diameter to thickness of corrugated steel pipe and steel content of steel section.On the basis of discussing the calculation method of axial compression bearing capacity of similar members,the calculation method of axial compression capacity of corrugated steel tubular steel reinforced concrete short columns is proposed,and the formula is verified by experiments and finite element examples.The results show that the calculation formula of axial compression capacity of corrugated steel tubular steel reinforced concrete is in good agreement with the finite element results.