Semi-rigid Steel Frame Research And Optimization Design

Among familiar steel buildings, steel frame structure system is not only used in multi-storey civil building but also adopted to multi-storey industrial structures, and be one of the main structural systems. With the social development and technological advancement, how to reduce steel consumption and improve the economy of the frame structure design, in other words, to achieve the optimal design of frame structure is a bottleneck question. According to the main line from joint optimization to the bar optimization and then to structure optimization, the paper will discuss in detail the entire optimization process of steel frame structure.In traditional steel design, the calculation of beam-column joints are usually simplified as an ideal hinge or completely rigid joint; in fact, the connection performance of most beam-column joints is semi-rigid characteristics. A great deal experiments show that the semi-rigid performance of joints has especially great influence on frame structures and can not be ignored. In order to realize the rational optimization on steel frame structures, the paper firstly deduced the static and dynamic finite element analysis process by considering the semi-rigid characteristics, which were the first step of the optimal design and the key of achieving rational optimization.Steel frame structure optimization design is very complicated problem, which includes not only all rods size optimization, and involves bracing system of topological optimization. According to different design requirements, the problem maybe relate to single objective optimization, also involves multi-objective optimization. This article will consider the particularity of steel frame optimization, such as the discrete variable and multi constraints, to improve traditional genetic algorithm and base-structure method to realize the semi-rigid steel frame structural static and dynamic sizing optimization and topology optimization.The main research work of this paper is as follows:1. Based on the zero length spring node model, the angle displacement equation and displacement shape function, the semi-rigid steel frame static and dynamic finite element analysis programs that can consider the effect of the node and the second semi-rigid case on frame were compiled. Then the joint connectivity and the second-order effect on the steel frame and bar mechanical properties were studied through calculating engineering examples.2. In order to realize single-objective optimization, a new improved dynamic population genetic algorithm without penalty function was proposed. Some improved strategies for the new GA can increase the global convergence and optimization efficiency. Then to combine the semi-rigid steel frame static analysis program with the improved GA, the static 'optimization program for semi-rigid steel frame was compiled. Through calculating engineering examples, the effect of semi-rigid connectivity on static size optimization was studied.3. According to the requirement of multi-objective anti-seismic design, a new multi-objective GA with multi-objective proportional sum value was proposed. Based on seismic requirements of steel frame structure, the dynamic multi-objective optimization procedure for semi-rigid steel frame was set up by combined the semi-rigid steel frame dynamic analysis procedures and the new multi-objective GA. Through calculating engineering examples, the effect of semi-rigid connectivity on dynamic size optimization was studied.4. To improve lateral stiffness of steel frame system based on the efficient and economic principles, topological optimization of bracing system was studied in detail. According to the node design requirement, the traditional base structure method was improved, and puts forward the rods beforehand delete criteria. For topological optimization process refers to size optimization and the topological optimization coupling relation, a new genetic algorithm coded form of integer and logic mixed code was proposed. In order to improve the optimization efficiency, the theory of grey relational analysis was introduced to supply constraint correlation step by step judgment criterion. Then, the improved genetic algorithm and base structure method combined with the semi-rigid steel frame static and dynamic analysis procedures to compile steel frame discrete topological optimization program. Based on the engineering examples, the effect of semi-rigid connectivity on bracing topology optimization was studied.Through the above related work, the theory about how to improve the design safety and economy of steel frame structure was given.