Internal Force Analysis And Optimal Design For Tapered Section Portal Frame

In recent years, structure of light-weightsteel is one of the vigorous styles in our country, in the light-weight steel system, portal frame has the installation of speed,cost savings,expansion flexibility,low maintenance charge,singleness Availability and the other advantage.Portal frame used tapered section to adjust to the bending moment changes in order to achieve the purpose of saving steel. This article discusses section optimization method of tapered section of potal frame light-weight steel structure and edit optimization program to calculate result to contrast design example, examples of comparative analysis conclude that optimization methods is of the importance in engineering design.This article analyzes the light-weight steel structure in the development of domestic and international , internal forces analysis of portal frame and optimal design of changed section. For the internal forces analysis of portal frame can use a variety of internal force analysis method . First to determine its structure and layout, in order to determine the basis of its calculation sketch, omitting secondary factor ease to analys and calculate, as far as possible, reflecting the actual structure of the main force characteristics. The portal frame structure is a statically indeterminable construction, we can use the graph multiplication method of structural mechanics to determine the basic structure ,then paint various loads of Mp chart and the chart M1. At last, we can calculate multiplication unknown forces with graph calculated excess, and work out the other internal forces. Calculation of the process is more cumbersome, but the analysis is clear, simple, easy to calculate, and its accuracy is also designed to meet the design requirements. The optimal design is the whole of the key elements, as well as the design of the essence.The portal frame use the penalty function method of optimized design , The portal frame can go to optimization design within the the volume as objective function, the structure, mechanical design requirements as constrained function.The research result can calculate the optimal value of every frame control section, we can reduce design time using the procedures which programmed by the discussion group, and give a good guiding for the engineering practice.