极寒环境下大跨贝雷梁钢管施工平台力学性能研究

In order to solve the problems of mechanical properties and construction safety of large-scale temporary steel structures in alpine regions, and to provide theoretical basis and engineering value for them, the influence of extreme cold environment on the mechanical properties of large-span Bailey beam steel pipe construction platforms was studied, this paper first uses the existing Bailey beam test results to verify the ABAQUS modeling technology. On this basis, based on the Bailey beam steel pipe construction platform (20 ℃) constructed at room temperature of a certain project, the variation of stress, structural displacement and local Bailey beam bearing capacity of the platform are analyzed when the ambient temperature is reduced to -10 ℃, -20 ℃, -30 ℃, -40 ℃ and -50 ℃. With the decrease of temperature, the stress of Bailey beam in the construction platform increases from 85.0 MPa at 20 ℃ to 232.2 MPa at -50 ℃, and the stress of steel tube column increases from 9.9 MPa at 20 ℃ to 108. 3MPa at -50 ℃. The displacement of Bailey beam increased from 3.7 mm at 20 ℃ to 44.7 mm at-50 ℃, and the displacement of steel tube column increased from 0.4 mm at 20 ℃ to 17.4 mm at -50 ℃. With the decrease of temperature, the influence of the diameter and wall thickness of the steel tube column on the stress change is gradually increasing. When the temperature dropped from 20 ℃ to -50 ℃ °C, the out-of-plane displacement of Bailey beam increased from 0.7 mm to 36.6mm, and the bearing capacity decreased from 561.8 kN to 475.5 kN, which decreased by 15.4%. The decrease of ambient temperature will lead to the increasing stress of Bailey beam and steel tube column; when the out-of-plane displacement of Bailey beam increases to a certain extent, it will have a significant impact on its own bearing capacity.