Study On Structural Design Method Of Y-type Eccentrically Braced Frame Based On Slip Connection

The eccentrically braced frame(EBF)has some advantages of both the frame structure and the concentrically braced frame.It is used in the design and construction of steel structures because of its high rigidity,shear capacity and good anti-seismic performance under the action of rare earthquake.However,there are some deficiencies of the eccentrically braced steel frame in the practical design and construction.Firstly,the elastic anti-seismic design method ‘semi-empirical formula + limited condition' is that it uses elastic-plastic analysis to design one structure,and applies inelastic analysis method to analyze this structure under the action of rare earthquake.However,its failure mode and failure degree may not meet the relevant anti-seismic demand.In addition,the current design methods tend to be conservative in the performance control of components,which often involves a large amount of calculation,wastes of steel and increases the cost.Secondly,the current development tendency of anti-seismic design is that the energy consumption of the structure is multistage and the function of the structure could rapidly recovery after earthquake happening.In fact,nowadays,links are always connected with the framed girder by rigid connection in EBFs.As a result,links will be broken.If it can be reused in the future,it still needs a large amount of structural repair work to repair,which is inconvenient for the rapid recovery of the function of the structure.Therefore,aim to these deficiencies in the design of EBFs,this paper has some research which will conduct the following research contents.Firstly,a convenient and effective design method is presented for EBFs,which is a plastic design method based on the function balance principle and the energy dissipation coefficient.In addition,a six-floor office building with Y-shaped EBFs is designed by this method,and is used to verify the correctness of this design method by a structural design software ‘SAP 2000' and the analysis of elastic and static push-over.Secondly,the plastic design method is used to design a 12-floor Y-shaped EBFs,and three seismic waves are selected on principle to make dynamic elastic-plastic calculations.Moreover,the inter-story drift of structure,the shear force distribution of the structure at peak time of earthquake,and the hysteretic loop curve of energy dissipated beam under seismic load are analyzed.They are proved that under the action of earthquake,as the first line of the earthquake-resistance of structures,links can dissipate seismic energy through its own plastic deformation and improve the ductility of structures and the anti-seismic performance.Thirdly,high-strength reaming bolt connection is added at the bottom of links to preliminarily consume energy.In this paper,the new Y-shaped EBF is compared with a common Y-shaped EBF,and results show that the anti-seismic performance of the new Y-shaped EBFs is more preferred.In addition,another structural analysis software ‘Perform-3D' is used to analyze the influence parameters of the bolt connected beam,include that increasing the friction coefficient of the bolt plate,the pre-tension of the bolt and the length of the long circular hole can effectively improve the energy dissipation capacity of energy dissipation beam and reaming bolt composite members,improve the ductility and seismic performance of the structure,and give full play to the seismic advantages of the members.Moreover,‘Perform-3D' is used to analyze the EBFs added shear slotted bolted connection(SSBC).Results show that when the rare earthquake happens,nearly 70% of the total energy is dissipated by SSBC and the hysteresis of links,this EBFs can greatly improve the anti-seismic performance of the structure.Finally,links make anti-seismic performance through SSBC.After earthquake,if links are broken,it can be repaired quickly.As a result,the structure can finish the antiseismic fortification goal of no damage in small and medium earthquake,a little damage in large earthquake and rapid recovery of structural functions.