Strategies for economic design of unbraced steel frames

In frame design for optimal economy, beam and column properties, as well as the properties of the joints, should be selected in such a way that economy can be achieved during fabrication. A method by which an impression of the possible layout of rigid joints can be obtained in a very early design stage is presented. The method is simple and straightforward, requiring only a limited amount of design information. It allows the effects of the increase of beam or column sections on the joint layout to be investigated. The joints normally will behave semirigid. The layout can be checked with a simple hand method based on the principle that the solution with semirigid joints should have the same performance as that with rigid joints.