Seismic Behavior Study Of V-typed Eccentrically Braced Steel Frames With Buckling-restrained Braces

Eccentrically braced steel frames can consume energy through the shear deformation of the energy dissipation beam,and the lateral buckling of the braced frame can not be guaranteed.However,when the span and height of the structure are large,the lateral support needs to increase the area of the cross section to meet the requirements of the stability and axial compression ratio.Buckling restrained braces(BRBs)under tension and compression are not prone to buckling and the effect of energy dissipation is good,so it is of certain value to use the BRB to replace the bracing of eccentrically braced steel frames.Firstly,the research object of this paper is the V type eccentrically braced steel frames with BRBs,simplify the model and calculate the equivalent damping and equivalent stiffness of the single degree of freedom model.The establishment of a common V type eccentrically braced steel frame(VEBF)and the steel frame with BRBs V type eccentrically braced(VEBF-B)model;The results of Push-over analysis show that the BRBs can slow down the development speed of the plastic hinge of the frame column and protect the frame column,and it's help to achieve the goal of seismic fortification "strong column and weak beam".Secondly,Comparison of the VEBF-B framework and VEBF framework in this paper,in the time history analysis show that: the VEBF-B frame's lateral displacement,base shear force and peak acceleration are smaller than those of the VEBF frame under common earthquakes,but the difference is not obvious.The main reason is that most BRBs not yield under common earthquakes,and is the same as that of ordinary braces,just increase the lateral stiffness of the structure.Under the rare earthquake,the seismic performance of VEBF-B frame and VEBF frame is very different,and the VEBF-B frame's lateral displacement,base shear force and peak acceleration are significantly reduced.Due to the large number of BRBs yield,theVEBF-B framework has the advantage of energy dissipation,which makes the whole structure more reasonable.The shear force of the VEBF-B frame is effectively reduced,which not only helps to improve the seismic performance of the structure,but also has a great advantage in reducing the cost of the structure.Finally,this paper shows that results from the energy balance principle of structure based on energy analysis: the BRBs of VEBF-B framework can consume most of the seismic energy and help reduce the damage of earthquake on the main structure;the more energy in the structure,the BRB energy dissipation ratio is greater.It is of theoretical significance and practical value to study the seismic performance of VEBF-B frame,to further optimize the seismic design of the structure and the economic performance of the building.