Research On Seismic Performance Of K-eccentrically Braced Frame With Replaceable Links In Semi-rigid Connection

When the eccentrically braced frame is subjected to a large horizontal load,it can consume seismic energy through the buckling deformation of the link,thereby protecting other structures from maintaining the elastic stage or part of the plastic stage under the action of large earthquakes,with higher bearing capacity and consumption ability.In the traditional eccentrically braced steel frame structure,the welding connection method is often used,and the energy dissipation beam and the frame beam are designed as a whole,which is not conducive to post-earthquake repair of the frame.In order to solve this problem,according to the design concept of "strong column and weak beam",Q235 steel with lower yield point is used as the link,and Q345 steel is used as other components of the frame,and the link is designed as flush end plate bolt connection The beam-column joints adopt the form of semi-rigid connection to prevent the brittle fracture between the nodes caused by the welded connection.At the same time,the link adopts the replaceable design,which is conducive to post-earthquake repair and improves the economic benefits of the structure.This paper analyzes the semi-rigid eccentrically braced steel frame with replaceable link through pseudo-static test and nonlinear finite element analysis.The details are as follows:(1)Carry out low-cycle loading test on two 1:2 scale single-layer single-span plane steel frames.The deformation characteristics,plastic development and failure modes of the frame were analyzed through experiments,and the strength,stiffness,hysteretic performance and energy consumption characteristics of the frame were analyzed.(2)Adopt ABAQUS finite element analysis software,establish a finite element solid model based on the test frame data,and perform nonlinear analysis on the model.The results show that the stress development,deformation and load-displacement curve of the model are in good agreement with the test.Fitting effect.(3)By varying the length of the link and the axial compression ratio of the frame,the difference in seismic performance of the frame is studied.The results show that the failure mainly occurs at the link,and the link yields and consumes energy before the frame;properly increasing the end plate thickness at the link can increase the horizontal bearing capacity of the frame.There is no buckling failure at the beam-column joint during the loading process.The bolts at the beamcolumn joint are less loaded,and the semi-rigid connection has less impact on the seismic performance of the frame.the shear link with a shorter length has higher bearing capacity and initial stiffness,and the longer length is not conducive to the energy consumption of shear deformation at the web of the energy dissipation beam.When the axial compression ratio is below 0.3,the axial compression ratio has little effect on the seismic performance of the frame.When the axial compression ratio reaches 0.6 and0.8,it is easy to cause the buckling of the column foot during loading.