| With the continuous development of the national economic level and the continuous innovation of building structure type,cold-formed thin-walled steel and lightweight aggregate concrete have gradually come into people’s sight.Because of its small weight and good heat insulation,lightweight aggregate concrete is not used as a load-bearing structure because of its low strength and inconvenient maintenance.The cold-formed thin-walled steel structure can reduce the amount of steel used and reduce the weight of the structure,but it is prone to local distortion and buckling and is greatly influenced by the initial defects.The thin-walled steel tube lightweight concrete can combine the two materials which have certain shortcomings well,the external steel pipe has a hoop effect on the internal concrete,which makes the concrete in the three-axis compression state and improves the strength of the concrete.The internal concrete can restrain the deformation of the steel pipe in the interior and delay the buckling of the steel.At the same time,to make the size of the thin-walled concrete-filled steel tube more flexible,the outer steel tube is designed as a self-tapping joint structure.To verify the reliability of the structure,the axial compression test and numerical simulation of 12 new cold-formed thin-walled steel-lightweight concrete cross-section composite columns and 4 empty steel tubes with unfilled lightweight concrete were carried out.The test results show that the new-type cold-formed thin-walled steel-lightweight concrete composite column has good bearing capacity,the failure is local buckling,and the ultimate bearing capacity of the specimen increases with the increase of section size,concrete strength grade,steel content and wall thickness.The formula for calculating the ultimate bearing capacity proposed in this paper has high precision and can be used as an important index to guide the design of the structure. |
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