Study On Buckling Performance Of Columns With Random Thickness Based On Kriging Method

Buckling is the main failure mode of steel structures.The initial imperfections,boundary conditions and load patterns will have different effects on their buckling performance.Initial imperfections mainly include geometric imperfections,material imperfections and load imperfections.Initial geometric imperfections are mainly caused by the fabrication and processing of structures or components.Deviation of the thickness is attributed to initial geometric imperfections,and its existence makes critical buckling loads different from the theoretical calculation or numerical prediction of the perfect structure.If influence of geometric imperfections of thin-walled component is not considered,prediction may be wrong.Therefore,the selection of a suitable initial geometric imperfections model to more accurately estimate critical loads has become a key issue in the buckling analysis.In this paper,a method for analyzing the buckling behavior of compression members considering the influence of random thickness imperfections is established.Firstly,the stochastic thickness imperfections model is established based on measured imperfections.Then,based on the Kriging interpolation theory,stochastic thickness is introduced into finite element model to analyze the buckling performance.Finally,different analysis of cross-section columns(I-section,H-section,T-section and 十-section)prove that it is reasonable.The specific work is as follows:(1)The uniformity of plate thickness and the continuum of each state are verified,and a correlation model of the random thickness is established.Based on measured thickness imperfections and kriging theory,finite element model of random steel thickness imperfections is established.According to thickness deviation of measuring points,thickness deviation of each element is obtained by the stochastic model,and finite element model is established by parameterization.(2)Three-dimensional finite element model of the steel columns is established,ultimate capacity and instability characteristics of columns are obtained.Uniform modal imperfections and random thickness imperfections are introduced for steel columns with different cross-section shapes.The effects of traditional deterministic imperfections and random plate thickness on buckling behavior of columns are analyzed.The results show that critical buckling load of the steel columns based on random thickness is closer to measured value than traditional modal imperfections.In addition,modal imperfections are combined with random plate thickness for columns,the results show that critical buckling load is closer to test results.(3)Based on I-section column,the effects of material properties,boundary conditions,slenderness ratio and eccentricity on the buckling capacity of imperfection columns are analyzed.The research shows that when the material and eccentricity are different,the influence of the random thickness imperfections on ultimate capacity of columns is unobvious.With the increase of boundary condition constraint,existence of random thickness causes the decrease of ultimate capacity to increase slightly.As the slenderness ratio increases,random thickness imperfections causes the decrease of ultimate capacity to gradually decrease,and eventually tends to be stable.