| The resistant earthquake properties of steel structure are superior to those structures made of other materials. Among steel structures, steel frame structures are always thought for one kind of perfect aseismatic systems. Steel frame structures have been widely applied in engineering field, especially in those regions where earthquakes happen frequently such as America and Japan since the seventies of the twenties century.Beam-column connections of steel frame structure are often designed to rigid joints which have enough stiffness and make the angle between members invariable before reaching its limit capabilities. The connecting strength should not under the yield strength of the members being connected. But, in the Northridge earthquake in America in 1994 and Kobe earthquake in Japan in 1995, the rigid joints of steel frame considered to have good aseismatic properties appeared lots of brittle failure and the beams didn' t appear plastic deformation obviously or plastic deformation didn' t happen at all. Thus, the researchers realized that the study on joint properties was still incomprehensive and it' s necessary to make well research on rigid joints of steel frame structures and discuss and seek the methods about improving joint properties to avoid brittle rupture.According to these problems mentioned above, this paper study on one kind of connection form being well researched in recently years what is called "dog bone section" or "Reduce Beam Section" from the point of ductility by general finite element program "ANSYS" . Elastic and el-plastic finite element analysis was made on the joints on which weakening parameters change and the effect of the changes of weakening parameters on joint properties has been analyzed from the aspect of stress and strain developing on key position, expansion of plastic region and load-carrying of joints. Finally, scale of ideal weakening parameters was reached and design method of dog-bone joints was suggested based on the research result. |
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