Research On The Stability Of Coupler-connected Scaffolding Steel Pipe Under Axial Compression

In the current scaffolding standard,the stability factor ? is directly quoted from the "Technical Specifications for Cold-Formed Thin-Walled Steel Structures" GB50018-2002,and the influence of different connected methods of steel pipes on the stability coefficient is not considered.Studies have shown that the mechanical properties of the coupler-connected scaffolding steel pipe are significantly different from those of non-connected steel pipes.Direct reference to the stability curve in the GB50018-2002 has hidden safety hazards.This article systematically studies the stable bearing capacity of the coupler-connected scaffolding steel pipe.The main works and results are as follows:(1)The finite element model of the stability of the coupler-connected scaffolding steel pipe was established,and the correctness of the model was verified by comparison with the existing test results.(2)The parametric analysis of the coupler-connected scaffolding steel pipe was considered,taking into account six parameters: the ratio of the length of the inner cross plate,the ratio of the length of the outer cover plate,the ratio of the diameter of the steel pipe,the ratio of the length of the upper and lower poles,the initial defect,and the bolt pretension force.The influence of the dimensionless parameters on the stability coefficient of the coupler-connected scaffolding steel pipe is obtained.It is recommended that the height of the inner cross plate is not less than 120 mm,the height of the outer cover plate is not less than 100 mm,the connected position should be close to both ends,the bolt preload force should be greater than 30 N / m,and the ratio of the diameter to thickness of the steel pipe is almost no effect.(3)Applying the stability coefficient formula in the design theory of pressure bar stability in "Standard for Design of Steel Structure " GB50017-2017,the stability curves of different initial defects under the coupler connection are fitted,,and the table of stability coefficients is given for design reference.(4)Contrast and analysis the differences in stability coefficients of non-connected vertical poles,sleeve-connected vertical poles,and coupler-connected vertical poles.When the regularized slenderness ratio is less than 1.0,the stability coefficients of the three connected methods are relatively close.For the convenience of construction and management,it is recommended to select the casing-connected method;when the regularized slenderness ratio is greater than 1.0,it is recommended to select the coupler-connected methods.