| According to the Code for Design of Steel Structures (GB 50017-2003),the beam-column nodes of steel frames can be divided into rigid nodes and hinge nodes.However, in actual engineering use, all the nodes are between the two kinds, which are called semi-rigid nodes. The beam-column end-plate connection is a typical semi-rigid connection. At present, the end-plate connections are designed as rigid joints in our Country for lacking of theories and method of calculations. So, how to choose a practical and accurate expression to describe the moment-rotation curve of semi-rigid end-plate connections and reflect the actual changes of node's rotational stiffness, become an important research topic in end-plate stiffness currently.The high-strength bolts are very important in the design of end-plate connections. The bolts which are less-tightened or super-tightened offen appear in the actual project. Now, in the acceptance of steel structure, there is no clearly provision about the less-tightened or super-tightened bolts.The portal frames are typical to light-weight steel structures. These structures are widely used in civil constructions because of their excellent overall performance and practical economy. However, the nodes of portal frames are designed as rigid nodes now, not considering the properties of semi-rigid end-plate connections. The semi-rigid connections not only have impact on the portal frames's displacements and internal forces, but also on the structural stabilities.For the above questions, works are done in this paper as follow:Firstly, the four-parameter exponential function model is verified as a high accurate calculation model. Practicality, this model can be used to describe the moment-rotation curve of semi-rigid end-plate in beam-column connections.Secondly, a solid model of beam-column node is established by using the finite element analysis software ANSYS in this paper. Futherly, the nonlinear moment-rotation curves of high reliability are obtained through extracting the results data from this model. These conclusions are valuable for the steel structures's designs and experiments. At last, a finite element model of four cross-portal frame under wind and snow loads is established, refering to actual project in Wuhan. Moreover, through two specific examples, some comprehensive comparisons among the rigid model, semi-rigid model and bolts less-tightened semi-rigid model have been done in the final chapter. These above analysis are significant for the actual projects.
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