| Because of the interaction between the steel pipe and concrete,the advantages of the two are complementary.The concrete filled steel tubular column has the advantages of high bearing capacity,good ductility,good fatigue property and impact resistance property.Scholars at home and abroad have done a lot of research on CCFST and achieved fruitful results.However,with the increasing height of the building and the increasing span of the building,the pressure of the column is increasing,and the demand for the earthquake resistance is becoming higher and higher.Therefore,the research on the concrete filled steel tube is becoming more and more deep.In this paper,the data of a large number of cylindrical concrete filled steel tubular(CCFST)stub tests under axial compression are collected.On the basis of the predecessors' theory and foundation,the calculation method of the bearing capacity of the axial compression short column of the circular concrete-filled steel tube is analyzed and compared.On the basis of the analysis and comparison,a revised formula is put forward.Finally,The comparison and analysis of reliability of the typical formula and the revised formula in this paper were carried out.The main research contents include the following aspects:(1)The three theoretical systems for calculating the bearing capacity of short cylindrical concrete filled steel tubular columns are systematically introduced,as well as some typical formulas at home and abroad,including standard regulations and some influential formulas proposed by some scholars.A large number of test data of short columns under axial compression were collected at home and abroad,and the above formulas are compared and analyzed.(2)On the basis of a large number of data,the influence of the confinement factor,the strength of concrete,the strength of the steel tube and the diameter of the steel tube on the accuracy of the formula is analyzed based on the two formulas in the technical specification for concrete filled steel tube(GB 50936-2014).At the same time,the axial compression failure mechanism of the CCFST short column is analyzed by utilizing the collected data.On the basis of the analysis results,the strength of steel tube,the strength of concrete and the size effect of the specimen are taken into consideration,and the revised formula of the bearing capacity of the concrete filled steel tubular short column is put forward by using the superposition principle.(3)Based on the Chinese standard(GB 50936-2014),the American specification(AISC),the European specification(EC4)and the modified formula,the reliability analysis of the cylindrical concrete filled steel tube axial compression short column is carried out.The calculation model error type,the steel ratio,the concrete strength,the strength of the steel tube,the load ratio,the load type and so on which influence of concrete axial compression short column reliability index are analyzed. |
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