Study On Bearing Capacity Of Steel Structure Of Passenger Station Canopy Under Atmospheric Corrosion

Atmospheric corrosion is an important factor affecting the durability of existing steel structures,especially outdoor structures.However,there is no unified method of characterizing corrosion degree and feasible method for calculating the load-carrying capacity due to the complexity of steel structure corrosion problem.This paper dealt with residual ultimate strength and durability design of steel structures of station canopies under different corrosion conditions.Firstly,the influence of ideal full-length corrosion on the load-carrying capacity of axial compression members was explored.Considering different cross-section forms and boundary conditions of members,the effect of uniform corrosion was analyzed by theoretical derivation,and verified by finite element methods and the test,which can be expressed as a simple combination of the effects of geometric section reduction and material strength reduction.Secondly,the ultimate load-carrying capacity of axial compression members under full-length random corrosion was studied.Based on the statistic of measured actual corrosion data,the finite element model of tubular columns with random pit corrosion was established to analyze the influence of full-length atmospheric pit corrosion.Based on the above uniform corrosion research,the fitting formula for the random corrosion load-carrying was obtained.Thirdly,the influence of local corrosion on axial compression members was investigated.The load-carrying capacity of axial compression members was studied under local uniform corrosion considering corrosion depth,corrosion height,corrosion location and corrosion shape,for different cross-section forms and slenderness ratios.Next,for the local random corrosion,the finite element model of tubular columns with local random pit corrosion was established conducting parametric studies on the load-carrying capacity after corrosion.Based on the above local uniform corrosion research,the fitting formula for local random corrosion load-carrying capacity was obtained.Finally,the influence of corrosion on steel structures of passenger station canopy was investigated.Two commonly used structural forms namely the portal frame and the arch truss were selected for studying the effect of uniform corrosion,and then the practical formula of residual load-carrying capacity coefficient of steel structure was proposed.Next,for local uniform corrosion,the load-carrying capacity of the portal frame was revealed when the corrosion was located at different regions of portal frame,considering the variation of slenderness ratios of column and beam span.Finally,the corrosion impact classification and durability evaluation method for steel structure of passenger station canopy were established.