Behavior of stainless steel sections subjected to non-homogeneous temperatures

There is an increasing interest in building load-bearing structures ofstainless steel because of its corrosion resistance, ease of maintenance, attractive appearance and low life-cycle costs. Full utilization of the special features of stainless steel has not been possible due to the lack of teclmical data for certain design aspects such as its fire resistance behavior. The influence of the elevated temperature on the strength of structural members is an important parameter in the design procedure.The bending moment capacity of the stainless steel cross section atelevated temperatures depends on many factors including the geometricalproperties, the residual stresses, the material properties as well as thetemperature distributions. During fire, the stainless steel structures areinfluenced by the elevated temperatures where, the modulus of elasticity,the yield strength and the local buckling resistance of the stainless steel members decrease with temperature increasing.The main objective of this research is to evaluate the bending momentcapacity about x and y axes of stainless steel cold-formed sections atelevated temperatures. The cross sections are subjected to general case of loading; cross sections also were analyzed under different temperaturedistributions depending on the fire conditions and their locations relativeto walls and slab. Bending moment capacity curves about x and y axes forchosen stainless steel profiles at different temperature distributions arepresented. The integration technique is done calculating numerically inincremental steps the capacity of the cross section. The equilibriummethod at plastic condition is considered. The research discusses also the effect of width / thickness ratio of compressed flat parts of the cross-section, the local buckling of those parts and the effect of adding stiffenerlips on the cross section bending moment capacity.A numerical model (SCFSA) was developed to carry out the requiredanalysis. This numerical model can handle general loading conditions inthe presence of the non-homogeneity of the temperature gradients on thecross section. A validation of the used assumptions and the developednumerical model was done. Six different cold-formed stainless steelsections were studied considering both linear and non-linear temperaturedistributions models based on previous theoretical and experimentalstudies. A full comparative parametric study was presented through thiswork. A structure was taken as a real applied example in which thecritical temperature and the time of total collapse were calculated.