Preliminary Minimum Weight Design of Moment Frames for Lateral Loading

This paper introduces a new concept for the design of regular rectangular moment frames under lateral loading. The concept is based on the assumption that the entire framework is composed of imaginary rectangular modules, with each module consisting of four uniform prismatic members rigidly connected at their ends. This concept entails the selection of the properties of the constituent elements of the modules in such a way as to reduce the total material consumption to a minimum, and at the same time maintain the least possible drift for the given loading and geometry. In addition to controlling the sideway deflections of the structure, the method presented not only reduces the otherwise complicated task of structural analysis to direct member size selection, but also it achieves substantial cost reductions by reducing the total weight of the structure to a minimum. The use of this concept results in an extremely simple yet powerful method of design for the class of structure treated in this study. Several numerical examples are presented to illustrate the practical applications of the concept. The validity and the consistancy of the proposed method in both the elastic and plastic ranges of behavior are established by the standard techniques of structural analysis.