Computer-automated synthesis of building frameworks

Abstract

The paper surveys recent work carried out at the University of Waterloo concerning the computer-automated synthesis of minimum-weight planar steel frameworks. For any number of applied loading schemes, the design of the structure may be constrained by a variety of service and (or) ultimate 'limit-states' performance criteria concerning stresses, displacements, and (or) plastic collapse loads. Fabrication conditions can be imposed to ensure member-continuity and structure-symmetry requirements. Member sizes can be taken as either continuous or discrete variables to the synthesis process, depending on whether custom or commercial-standard sections are available for the design. In the latter case, the structure may be automatically sized using the standard sections specified by a variety of different steel design codes (to date, Canadian Institute of Steel Construction (CISC) and American Institute of Steel Construction (AISC) sections have been investigated).The computer-based design method is iterative in nature and is remarkably effective and efficient. Commencing with an arbitrarily chosen initial 'trial' design, the synthesis process determines the 'minimum-weight' structure satisfying all of the imposed performance and fabrication conditions without further designer intervention. The number of iterations required to achieve the optimal design is generally small and almost totally independent of the complexity of the structure.Three different designs of a building framework are presented to illustrate the scope of the method: limit-states design using CISC sections; working-stress design using AISC sections; and design under elastic and plastic performance criteria using custom sections. Key words: steel, frameworks, standard sections, custom sections, synthesis, minimum weight, limit states, computers, automated.