Automatic Analysis of Plane Framed Structures with Semi-Rigid Connections for Combined Multiple Load Sets

Abstract

Usually, the analysis and project of framed steel structures are developed under the assumption of a simplified behavior of the connections between beams and columns. Or the connection is total flexible (pinned), or is total rigid. A total flexible connection allows that the beam turns freely under the action of the loading without occurring transference of bending moment among the elements. Therefore, the rigid connection supports loads without that it has change of the original angle between its members. The experimental research shows that almost all of the connections present an intermediate behavior between these two extremes, allowing a parcel of relative rotation and transmitting of an element for the other, part of the operating moment, being classified as semirigid connections. In this work a Genetic Algorithm (GA) for the optimization and automatic analysis evaluation of commercial transversal sections of the structure is applied. Numerical examples are presented to illustrate the applicability of the algorithm multiple load sets in consideration the curves of the CRC (Column Research Council), the LRFD (American Institute of Steel Construction) and the NBR 8800 (Brazilian Association of Norms Techniques). The normal deformations are taken in consideration in the structural analysis Such methodology suggests a sizing of sections that can be used in the real world for the designers of steel structures and to show the possibility of economy at the order of 20%-30% in the sizing of the beams due to semi-rigid connections.