Study On Stress Concentration And Reinforcement Scheme For Openings In Prefabricated Steel Silo Walls

As a new type of thin-walled structure, a prefabricated steel silo has been widely used fortransferring and storing materials in all nations and regions with the advantages of coveringsmall, storing large, constructing fast and etc. In order to meet the technologicalrequirements，some openings are punched in the silo wall, especially the manway which isopened at the bottom of the silo wall. The destruction of structure’s geometric continuity andthe obvious stress concentration which are brought by the openings in the silo wall decreasethe structure’s carrying capacity and using life. The current Chinese code for design of grainsteel silos(GB50322-2011) shows us only stress calculation method of welding grain steel silowall opening, but doesn’t show the reinforcement scheme. The stress concentration at theperforated region of a prefabricated steel silo wall and the particular reinforcement scheme areproposed and analyzed, which has practical engineering significance.Finite Element Analysis (FEA) software-ANSYS is used to construct finite elementmodels of the cylindrical shell-structures with the bottom’s opening which suffer internalpress and axial press that are carried on a practical engineering prefabricated steel silo withmanway, and then considering the influence of the opening’s type and size on stressconcentration, the variation of stress concentration coefficient is concluded. Meanwhile, thepossibility of two reinforcement schemes of the rectangular opening in the prefabricated steelsilo wall is proposed and validated by this thesis which refers to the method of reinforcing paddesign. The main contents and conclusions are presented as follows：(1) In the view of a prefabricated steel silo which dig rectangular and circle manways，ANSYS is utilized to construct finite element models that are based on the cylindricalshell-structures with the bottom’s opening which suffer internal press and axial press.Considering the influence of the two kinds of opening’s size on stress concentration, the resultof this research is determined, which include that no matter which style the opening is, stressconcentration factor firstly increases, and then drops back to the data that is stable, finallycontinues to increase as the opening’s size increases.(2) The reinforcement method of openings on pressure vessel is introduced into thedesign for reinforcement scheme of the opening in prefabricated steel silo wall. Two kinds offinite element models which suffer internal press and axial press are selected and constructedby the method of reinforcing pad design. By comparative analysis of the stress and deformation of the two models before and after the reinforcement, the conclusion that theeffect of the reinforcement is obvious is reached.