Study On Interfacial Force Transfercharacteristics Of Concrete Filled Rectangular Steel Tubular Members

Concrete-filled steel tube(CFST)has the advantages of high bearing capacity,good ductility and good seismic performance.It has attracted the attention of scholars at home and abroad and the engineering community.The interface slip of concrete filled steel tube has seriously restricted the mechanical properties of concrete filled steel tube.It has been the focus of research at home and abroad.This paper through acoustic emission technology,acquisition of concrete filled steel tube column launch produced during the test process of the acoustic emission signals obtained load,strain of steel and the acoustic emission signal changes,provide a reference for the study on the bond slip of steel pipe concrete.AE technology has been widely used in the field of damage monitoring and force monitoring of various materials since it was born.Scholars at home and abroad have also applied it to concrete damage detection.The existing research results show that acoustic emission characteristic parameters can reflect the damage degree of concrete.The steel pipe concrete short column is collected through an external steel tube strain gauge.In the test,the strain of the steel pipe varies with the column height,and the strain distribution is approximately exponential.Acoustic emission test was used to collect the acoustic signals produced during launching test,and the relationship between AE characteristic parameters and load was analyzed.The characteristics of AE characteristic parameters at different loading stages are discussed,and the relationship between AE characteristic parameters and interfacial adhesive force is analyzed.Found that the AE characteristic parameters of impact and energy changes can correspond to specimen bond slip stage,there is contact force and bond,impact cumulative curve linear growth after exponential growth curve analysis of typical AE characteristic parameters,characteristic parameters of acoustic emission can be found mutation before reaching the ultimate load.Through the analysis of AE characteristic parameters at different loading stages,the development law of bond slip in concrete-filled steel tube short column launching test is analyzed.It is found that the bond stress distribution is concentrated at the loading end at the beginning of loading,and develops to the middle of the specimen as the load increases.When the limit load is reached,the slip passes through the whole interface of the column,and the cohesive force composition changes at the same time.Through the analysis,the initial loading of acoustic emission source at the interface in the form of exponential distribution,with the increasing of load,the ultimate load is close to linear distribution,the ultimate load interface after the acoustic emission source on the central interface,show a parabolic distribution.The development of different acoustic emission detection equipment parameter setting scheme,comparing the different programs to collect acoustic emission characteristic parameters,set on the AE characteristic parameters with the load parameters analysis of acoustic emission detection instrument,obtains a better solution.