Study On Seismic Resistance And Seismic Demand Performance Of Brbf Structure With Rigid Joint And Bolt Joint

The buckling restrained brace(BRB)has the advantages of improving the rigidity and bearing capacity of the steel structure.The buckling restrained brace(BRBF)structure is a dual lateral force system and has good seismic performance.Therefore,BRB steel frames are widely used in Japan and the United States and Taiwan and other countries and regions.In previous earthquakes,steel structure beam-column joints were easily damaged to varying degrees.This phenomenon was particularly obvious in the Northridge Earthquake in the United States and the Hanshin Earthquake in Japan.In the earthquake,many steel structure buildings suffered damage or even brittle fracture at the beam-column joints.Therefore,in order to study the seismic resistance and seismic demand performance of beam-column joints and BRBF overall structure,the research embarks from the rigid joint and bolt joint of the beam and column,and compares and analyzes the seismic resistance and seismic demand performance of two different connection of the BRBF structure.In this research,three basic research models of the 8-story BRBF structure with rigid joint of the beam and column with β values of 20%,30%,and 40% are designed,and three corresponding 8-story BRBF structural models of with bolted joint of the beam and column were obtained through the transformation of the beam-column joints.Then use CLAP software to perform static and dynamic elasto-plastic analysis of the research model.First,carry out the elasto-plastic static pushover analysis based on displacement control to study the structure’s seismic performance such as the plastic hinge mechanism and distribution law of the structure,the relationship between layer shear and interlayer displacement.Then input five natural seismic waves and two artificial seismic waves that comply with my country’s "Code for Seismic Design of Buildings" for dynamic elasto-plastic time history analysis of the structure,and study the seismic demand performance such as the maximum inter-story displacement relationship,maximum inter-story shear relationship,plastic energy distribution,damage energy sharing rate,residual deformation and hysteresis curve of the structural models with two different joints connection.The research results are as follows:The seismic performance of BRBF structure during static analysis:(1)BRB all appear plastic hinges earlier than the beam ends,which effectively reduces the burden on the frame columns and beams.(2)The beam ends of the bolt joints to the BRBF structure form plastic hinges earlier,and the plastic hinges to each layer distribution.The beam end of the rigid joints to the BRBF structure forms plastic hinges later,and the plastic hinges are basically distributed to each layer.The BRBF structure of the two connection forms has good ductility and forms an overall failure system.(3)After the beam-column joints is converted from rigid connection to bolt connection,when the elastic or elastic-plastic interval displacement angle limit is reached,the first layer bearing capacity and stiffness of the model are significantly reduced.The seismic demand performance of the BRBF structure in the elasto-plastic time history analysis:(1)the BRBF of the bolt joint has a large interlayer displacement response,and the deformation of the lower layer is obviously concentrated,while the BRBF of the rigid joint has a greater shear response;(2)BRB has a large damage energy sharing rate,which improves the phenomenon of beam end energy protruding;(3)Under the same seismic acceleration peak conditions,the layer energy and beam end energy of the bolt joint model are greater than those of the rigid joint model;(4)The lower part of the BRBF structure with two beam-column connection forms accounts for a large proportion of energy consumption.Among them,the bolt joint model has the largest energy consumption component and the hysteretic curve area is larger,and the seismic demand consumes more energy.