Study On Nonlinear Behaviour And Structural Design Method Of Large-scale Thin-walled Steel Flues

With the fast development of China’s current industries, the apparatus fordenitration of smoke released in the process of electricity production has beenwidely used in power plants. These facilities consist of thin-walled stiffened platesand other members such as internal overarm support. The stability and effectivedesign methods of these structures still remain to be solved. The presentspecification for the design of steel flues can not serve the purpose of constructionof the large-scale flues.In this paper, based on large deflection theory, the nonlinear structuralproperties of flues are investigated by using ANSYS software. The effect ofstiffeners and internal overarm support on the mechanical property of flues is alsoinvolved in the research. Besides, the linear and nonlinear stability of stiffenedplates is studied. At the end of the thesis, post-buckling strength of the stiffenedplate is simply analyzed.The results show that due to the consideration of the large-deflection effects,the equivalent Mises stress of flues decreases by8%to54%while the deflectionof flues increases by8%to57%. This phenomenon for long flues will be moreconspicuous. While designing the internal overarm support of flues, it is importantto make sure that all stiffened plates of flues, including top plates, bottom platesand lateral plates, can be combined together to effectively carry external loads.The internal poles at the transverse direction are always the prior design and ifnecessary, the internal poles at the longitudinal direction can act as constructionalmeasures to improve the overall carrying capacity of flues. It is economical to useangel steel as the stiffeners of flues. The linear and nonlinear buckling loads of thestiffened plates are obviously influenced by its ratio of flexural stiffness. Theoptimum ratio of flexural stiffness ranges from10to20.The study on how to properly select the forms of stiffeners is one innovationin this paper. Another innovation is the research about the effect of the ratio offlexural stiffness on the stability of stiffened plates.