Optimization Design Of Portal Frame Structures Based On APDL

Portal Frame Structural is the most normal light-weight steel structural which is widely used in china, and there is great improve on the level of design,manufacture and construction. As now, there are 200 million square meters of light weight-steel buildings new builded per year. But the traditional design method is "trial and error" method, that is firstly suppose the section dimentions according to the experience of the designer, and then try to examine the strength,stiffness,stability and some other restrictions. Usually the economical efficiency of the structures is ingnored. Thus, it is necessary and significant to study the application of design optimization theory in the field of steel structure design.ANSYS is well known as the most powerful FEA program widely used in the field of computer aided engineering. The ANSYS parametric design language APDL and the Design Optimization module attached in ANSYS is an efficacious way to optain the best design set of the light-weight steel structure.The object of this paper is try to illustrate the basic theory of design optimization and the operation steps of ANSYS parametric analysis, and then optimize a light-weight tapered portal frame structure of three spans based on APDL, in this process, the section parameters such as the width,height and thickness of the flags are studied as the design variables, the stress,translation and stability is studied as state variables, the total weight of the structure is processed an the object function. At the end of the thesis, the analysis results ANSYS and STS is compared,All of the optimization steps is operated under the restriction of the relationed design codes, such as GB 50011-2001 and CECS 102:2002. Command streams of the whole optimization design steps is listed in chap. 3, it can be a beter reference of the static,dynamic,model and antiseismic analysis based on ANSYS.