الفهرس | Only 14 pages are availabe for public view |
Abstract In the last two decades a significant increase in the number of researches on optimal structural design for stell frames have been carried out. Two of the most imoprtant aspects that lead to more economic design are, the geometrical configuration of the frame elements and the use of semi-rigid connections concept. The present research discusses the effect of taperred beam elements and semi-rigid connections on the behaviour of steel frames. TThe stiffness matrices and the equivalent nodal for tapered beams of any cross-sectional shape are derived. The principle of virtual work has been adopted. The fixed end actions have been formulated by the momnt-area theorem. A method is proposed for modeling the tapered elements with semi-rigid connections. the effect of semi-rigid connections on the behaviour of frames with haunched beams has been also discussed. The problem of buckling has been investigated. Acomputer program based on the direct stiffness method for the analysis and optimiziation of plane steel frames with haunched beams and semi-rigid connections is developed. This program is used to cerry out an optimum weght analysis for plane steel frames. An optimum weight analysis for portal and gable frames with haunched beams and semi-rigid connections has been applied. The effect of different parameters on the optimum weight are considered which are, the effect of haunched dimensions, the rigidity ratio of connectios and the frame dimensions. Based on the obtained results, a saving in steel weight has been achieved as well as an important in the stability performance. |