Research On Damage Constitutive Law Of Flush End-plate Beam-column Connection Of Steel Frame

Flush end-plate beam-column connection of steel frame is a typical semi-rigid connection. However, the study into end-plate connection is relatively late in China, and there is a lack of deep understanding of its mechanical characteristics. Moreover, our design code doesn’t give a moment-rotation curve and a specific calculation method which are indispensable to the design and calculation of semi-rigid connections. The design of flush end-plate connections in actual structural is simply considered as fully rigid or ideal hinged, which is clearly error.The emphasis of this study is the moment-rotation relationship of semi-rigid connections. On the basis of searching a large number of Chinese and foreign literature, this paper reviewed the research status and achievements at home and abroad of semi-rigid end-plate beam-column connections, introduced the mechanical characteristics of semi-rigid steel frame beam-column connections, summarized the mathematical model of previous research about moment-rotation relationship curve of semi-rigid joints. After introducing the basic theory of the finite element method, establish the finite element model of the flush end-plate connections by using Finite element software ANSYS, and finite element analysis results are consistent with the experimental results. Established eleven finite element models of five kinds semi-rigid flush end-plate connections, which are end-plate thickness, the distance from bolts to the flange and the web of the beam, the diameter of the bolt, column web stiffeners. Through analysis and comparison of the moment-rotation relationship curves of the five kinds finite element models, discussed the influence of each parameter on the mechanical properties of semi-rigid joints.From the perspective of material injury, explored the physical mechanisms of damage development of beam-column semi-rigid connections in Moment. On the mesoscopic level, the meso unit is characterized by bending micro-spring. A mesoscopic model of parallel springs is established for the analysis of the macro-mechanical behavior of flush end-plate connections. And then derived a moment-rotation relationship model which has the theoretical basis. A mean damage function forms have been proposed to describe the damage development of the flush end-plate semi-rigid connections in order to get the specific formula. To calculate the two important parameters in the constitutive model, the ultimate moment and initial stiffness, reference is made to Eurocode EC3calculation method and the results of researchers. Further to simulate the constitutive relations of the flush end-plate connection and the results demonstrate the effectiveness of the model of this article.