Research On Optimization Of Portal Frame Structure With Variable Cross-section Based On Stressed Skin Diaphragm

In light steel structure,portal frame structure is one of the most widely used structures in China at present.However,in the process of design,the section size of the component is usually determined by the experience of the designer.After simple trial calculation and adjustment,it will be the final design section.This design method obviously has the situation of material waste,so it is very necessary to optimize its structure.Moreover,in the design of portal frame structure,only the force acting on the main frame is considered,while the effect of the most peripheral profiled steel plate is neglected.When the profiled steel plate and the main steel frame are connected reliably,the stressed skin diaphragm will be produced and the overall performance of the structure will be strengthened.Therefore,considering the stressed skin diaphragm in the optimization design can make the optimization result more reasonable.On the basis of previous studies,this paper combines the skin effect with structural optimization design,and carries out the following research by means of finite element analysis:(1)Introducing the portal frame structure system,introduces the concept of stressed skin diaphragm on the basis of traditional calculation model,and summarizes the conditions and principles of its generation.(2)A portal frame structure with variable cross-section is selected as an engineering example,and the finite element simulation software is used to establish the portal frame structure model under the traditional design mode,and its internal force and displacement are analyzed.Then the model is optimized,and the results show that the steel consumption is reduced by 21.29%.(3)Summarizing the method that profiled steel plate is equivalent to orthotropic plate,calculates the equivalent material parameters,establishes the finite element integral model of two kinds of portal frame structures with variable cross-section considering stressed skin diaphragm and without stressed skin diaphragm,compares and analyses their mechanical properties,and studies the influence of skin effect on structural performance.(4)The optimum control program is compiled and the finite element model considering stressed skin diaphragm is optimized.The optimum result shows that the steel consumption is reduced by 35.9%.It shows that considering stressed skin diaphragm in the design stage and optimization process of portal frame structure has great engineering significance and economic value.