The Research On The Performance Of Steel-braced Frames

In the steel frame systems,the concentrically braced steel frame (CBSF) has good lateralforce resistance performance,is one of the most common used lateral force resisting system inthe rise steel structure,and also it has broad prospects for engineering applications.However,because of the brace and the frame have different lateral force resistancecapacity,the integrated structure stress performance become very complicated,now researcheson the CBSF structure are finite in our country,and theoretical study lags behind engineeringpractice,therefore researching for its performance has an important theoretical significanceand engineering applications value.In this paper,concentrically braced steel frame (CBSF) model was established,whichusing Sap2000software and setting up three-dimensional model to study the finite elementnumerical simulation.Considering about the influence on the performance of steel-bracedframes from series model of different brace category,different brace layout and differentslenderness ratio of the brace,establishing13models,using modal analysis and static elastic-plastic analysis,study structure’s period,floor displacement,story drift angle and plastichinges’s development regular and distribution characteristic.The research show that: the period,the floor displacement and the story drift angle ofpure frame are much larger than the inverted-V concentrically braced steel frame (CBSF), thestiffness and the lateral force resistance performance of the inverted-V CBSF is much betterthan the pure frame.The period,the floor displacement and the story drift angle of theV-shaped CBSF are larger than the inverted-V CBSF, the stiffness and the lateral forceresistance performance of the inverted-V CBSF is superior to the V-shaped CBSF. Differentbrace layout of the CBSF has a obvious impact on the whole structure seismic behavior,thebrace layout of the CBSF is suggested using form of uniform layout in each span or"Z"-shaped layout in all span;brace as the first defense line of structure seismic appear plastichinge in the first place,then beams yield,at last column yield,in the case of frequently occurredearthquake,the frame is in the elastic morph stage and there is no plastic hinge,while in the case of seldomly occurred earthquake,the frame is in the elastic-plastic morph stage,lots ofbrace and beam yield,while the column is in the elastic morph stage.With the increasing ofbrace slenderness ratio,the period, the floor displacement and the story drift angle of theCBSF are both increasing; the bigger brace slenderness ratio,the better plastic development ofthe frame’s each components.