Influence Of BRB Form And Location On Seismic Performance Of High-rise Steel Frame

Steel structure has certain application advantages in earthquake-prone areas and many countries located on seismic belts,because of its light weight,high strength and good ductility.However,the lateral stiffness of ordinary steel frames(OSF)is small,which may cause the structure is easy to lose stability and damage when they suffer the action of large earthquakes or strong earthquakes.Subsequently,many experts and scholars through a large number of research have discovered that adding support members to steel frames can effectively improve the lateral stiffness of OSF structures,but the problem is that traditional support members are prone to buckling under compression when they suffer earthquakes,that will aggravate the earthquake damage and make the structural damage more serious when the structure is subjected to repeated buckling.Based on this,some scholars have developed a member,which it is called for Buckling Restrained Brace(BRB),it only yields but does not buckle under the action of tension or compression,so it can effectively improve the shortcomings of traditional support members.Therefore,if BRB is reasonably added to the frame structure,it can improve the seismic capacity of the building structure,but how to arrange the BRB reasonably and select an effective BRB form to make it can give full play to the energy consumption and shock absorption effect,which is of great significance for improving the seismic safety of the building structure.In this paper,two types of structural systems are used as the research object—OSF and BRB steel frame(BRBF),and builds a total of ten 12-layer 6-span models,which include one OSF model and nine BRBF models that is established on the basis of OSF.Furthermore,the CLAP analysis software which considers the effects of second-order nonlinearity is used to compare and analyze the seismic performance of the two types of structural systems,and evaluate the effects of different BRB forms and their layout positions on the seismic performance of the structure.In the pushover analysis,this paper discusses the plastic hinges of each model and its distribution law,as well as the relationship between layer shear force and layer displacement.In the dynamic elasto-plastic time history analysis,this paper analyzes the maximum inter-layer displacement relationship,maximum layer shear relationship,elasto-plastic energy distribution,maximum residual deformation relationship,and the force,deformation and energy consumption of BRB of each model.The results of the study are as follows:Pushover analysis: comparison of the two types of structural systems shows that BRBF has higher seismic performance than OSF structures,after the addition of BRB,the stiffness of the first story and the lateral force resistance of the structure are enhanced;When BRB has the same layout position but in the different form,the seismic performance of the herringbone BRB structure is higher than other BRB forms;When the same structure but in different layout positions of BRB,the energy consumption effect is better when the BRB is placed on the center span.Dynamic elasto-plastic time history analysis: comparing the two types of structural systems,the inter-story displacement of the structure after the addition of BRB is greatly reduced,the energy consumption and shock absorption effect of BRB is significant,and the lateral resistance and seismic effect of BRBF are significantly higher than OSF;When BRB has the same layout position but in the different form,the use of herringbone BRB can more effectively control the maximum inter-layer displacement and the structure deformation is small,so that the energy consumption and shock absorption effect are better;When the same structure but in different layout positions of BRB,when the BRB is placed on the center span,it’s energy consumption performance is fully utilized,but some structures are less affected by the location of the BRB;The energy consumption of BRBF is distributed on the BRB components,which can effectively protect the main structure,among them,the single-slope BRB structure consumes more energy,but it’s deformation is also bigger than others,so the positive effect of single-slope BRB structure’s seismic effect is not very well;BRB has excellent energy consumption effect and can effectively absorb seismic energy because of it has full hysteresis curve and small plastic deformation of its structure.