New Plastic Analysis Procedure for Collapse Prediction of Braced Frames by Means of Genetic Algorithm

Abstract

The analysis of frames and the determination of their collapse mechanisms and related loads are desirable for structural designers and also attractive for researchers. Plastic analysis method is one of the most effective and most used methods in this field. Analysis of moment frames has been carried out with the aid of simple plastic analysis by numerous researchers. However, analysis of braced frames due to the buckling of braces and the presence of axial and shear forces simultaneously in the frame members is very complex, and therefore, little research has been done in this area. In this research, a special procedure for the plastic analysis of steel braced frames has been presented. Using the genetic algorithm (GA) and necessary optimizations, a program has been proposed to determine the failure mechanism and collapse load of steel braced frames based on this procedure. The comparison of the results with pushover analysis shows that the proposed procedure is very accurate and is able to determine the critical failure mode and its corresponding load. The genetic algorithm also facilitates the use of this procedure, resulting in very high speed and limited effort of the hardware system to determine the load factor and failure mode of complex braced frames.