The Research Of Vertical Bearing Capacity Of Lightweight Aggregate Concrete-filled Round Double Skin Steel Tube Columns

Lightweight aggregate concrete-filled round double skin steel tube column is a newkind of concrete-filled steel tube column which filled with lightweight aggregate concrete.As the advantages of high bearing capacity, light quality, wide cross section, it has a goodapplication prospect in bridge engineering, wind power tower, high-rise structureengineering and so on. Previous research of lightweight aggregate concrete-filled rounddouble skin steel tube column is insufficient. In this paper, the ultimate bearing capacityand stress mechanism under axial loads were researched by means of the ANSYS finiteelement simulation and theoretical analysis, which can be used to provide a reference fordesign and engineering application of such members.Finite element results of lightweight aggregate concrete-filled round double skin steeltube short columns were calculated, in which the parameters of the steel tube thicknessratio, the hollow rate, the concrete strength and the strength of the steel were mainlyconsidered. This paper analyzes the whole process of lightweight aggregate concrete-filledround double skin steel tube column under axial load, and researches the stress mechanism.The unified strength theory was applied to analyze the stress of lightweight aggregateconcrete-filled round double skin steel tube columns, and the calculation method ofultimate bearing capacity was deduced. The results of theoretical calculation are in goodagreement with the finite element method calculation results which verified the accuracyof the formula. The effects of several factors to bearing capacity of short columns wereanalyzed and suggestions for the design of reasonable geometric parameters were putforward: the tube diameter to thickness ratio is30~45, the inner steel pipe diameterthickness ratio is50~88, hollow ratio is0.34~0.51.Finite element model of lightweight aggregate concrete-filled round double skin steeltube medium and long columns were established and the ultimate load were calculated.The stress mechanism was analyzed by means of the load-strain curve, the loaddeflection curve, combine the stress of the steel tube and light aggregate concrete in each stages. The method of orthogonal experiment showed that slenderness ratio and diameterthickness ratio of steel tube inside had great influence on the stability of medium and longconcrete columns. Based on the MATLAB software, regression fitting28specimens withdifferent parameters of finite element calculation results, stability coefficient calculationformula of lightweight aggregate concrete-filled round double skin steel tube medium andlong column is put forward.