Research On Seismic Control Of Steel Frame Structure Under Near Field Earthquake Action

As is known to all,there are generally three methods for seismic design of structures: traditional structure,vibration isolation structure,energy dissipation structure.Traditionally,the seismic performance(strength,stiffness,ductility)of the structure itself is enhanced to withstand seismic load,which is a passive seismic strategy.Vibration isolation structure is to set up a vibration isolation device(rubber bearings)between the building foundation and the superstructure to form a vibration isolation layer.Vibration isolation device is used to consume seismic energy to avoid the transmission of seismic energy to the superstructure,thus protecting the superstructure.The vibration isolation structure prolongs the period of the structure and reduces the acceleration response of the structure greatly.At the same time,the displacement of the structure is concentrated in the isolation layer.The relative displacement of the superstructure is very small,the structure is in an elastic state,and the building will not be damaged.Energy dissipation and seismic structure is to install energy dissipation devices(dampers)in some parts of the structure,through energy dissipation devices to reduce the seismic response of the main structure.In this paper,the damping performance of steel frame structures under near-field earthquakes is analyzed and compared in terms of natural vibration period,hysteretic curve,base shear force and vertex displacement.(1)In this paper,the damping analysis of steel frame structures subjected to near-field earthquake is studied,and its theoretical basis is introduced from three aspects.Firstly,the basic characteristics of near-field seismic motion are given in detail,which will pave the way for further research on seismic performance of different structures.Secondly,the analysis theory of SAP2000 finite element software is given.Finally,the aseismic design theory of the damping structure(additional isolation bearing structure and additional viscous damper structure)adopted in this paper is given,which will lay a theoretical foundation for the subsequent aseismic analysis.(2)Through the design of three different six-storey structural example models,the structural model with additional isolation bearings and the structural model with additional viscous dampers are compared with the traditional pure frame structure model,and the damping effect of the structure is examined from the modal analysis,internal force distribution,displacement,hysteretic curve,shear force and other indicators.The comparison results of each index show that the damping effect of the structure with additional isolation bearings,additional viscous dampers and additional isolation bearings + viscous dampers is more obvious than that of the pure frame structure.The conclusion can be drawn from the internal force distribution,the vertex displacement,the base shear force,the story displacement and so on.Numerical results show that the damping effect of attached viscous damper structure and additional isolation bearing + viscous damper structure is more obvious than that of additional isolation bearing.(3)The structure is further designed by optimizing the design scheme,so that the structure can not only achieve the effect of shock absorption,but also maximize the use of resources.Similarly,the structure is compared with the previous pure frame structure.The structure is divided into eight working conditions for design and analysis,through the analysis of various working conditions and pure frame structure,the final result is obtained.From the results of various parameters,it can be concluded that for the first four working conditions without additional isolation bearings,the internal force decreases more obviously than the third pure frame structure;the structure chooses the bottom 1-3 stories and odd stories when the damper is arranged,and the effect of isolation bearings will be improved.It is more obvious that the location of the damper has little effect on the base shear force when the structure is attached with isolation bearings;the hysteretic loops of the structure with additional isolation bearings are very full under working conditions 6 and 8,which indicates that the location of the damper has a great influence on the hysteretic performance of the structure.