الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 142 |  |  |
| | | from | 142 | | |
Abstract
Portal frames sre one of the most important structures in the family of steel industrial buildings. Consequently, the minimization of the design weight had been a legitimate goal for the designers and researchers for the last few decades. The goal of maost optimal steel design problems is to minimize the cost while satisfying performance and construction criteria. Traditionally, the design problem has been solved bt trail-and-error dicated by design specifications and guided by the experience and intuition of the designer. However, researches are continually developing analysis and optimization tools to assist engineers in the sometimes laborious design process and to foster creativity in arriving at the optimal design. Over the past decade, the innovation of these design tools has escalated with the advent of high-speed computer processors.
The focus of this research is to develop an optimization algorithm for the design of single and multi-bay steel portal frames under multiple loadings. Design equations involving local buckling, lateral torsional buckling, shear buckling, combined stresses and deflection contraints, as provided by the latest egyptian code of practice for steel construction and bridges are considered in this work. The objective function is chosen as the minimum weight of the structure. The design variables are the cross-sectional dimensional of the built-up sections for rafters and columns.
The design constraints cover all cases of discontinuity for compact and noncompact prismatic sections. Ordinary mild-steel and high-tensile steel cases are considered. The optimization technique adopted in this research is the modified method of feasible directions by using the automated design synthesis ADS software. A closed from solutions based on the virtual work method is used to analyze the single bay steel frame, and a computer program based on the displacement method is used to solve multi-bay steel portal frames. Several examples are presented to validate the efficiency of the formulation and to prove that the designs aotained in this work are more economical than those provided by other classical design approaches.