| The structural form of single-span frame structure had insufficient seismic redundancy and single seismic line of defense.Under the action of earthquake,its column members are easy to be damaged,resulting in continuous collapse of the structure.Article 6.1.5 of the current Code for Seismic Design of Buildings(GB50011-2010)stipulated that singlespan frames should not be used in seismic design of frame structures.Therefore,it is necessary to strengthen the teaching buildings and dormitory buildings in primary and secondary schools which do not meet the standard in the earthquake area.Based on the reinforced concrete single-span frame structure of a four-story teaching building,this paper analyzed the strengthen effect of adding Buckling-restrained-bracing(BRB)and shear wall to the frame structure.Midas software was used to analyze the seismic performance of the single-span frame structure before reinforcement,the BRB frame structure and the frame shear wall structure after strengthen.The analysis methods included the response spectrum analysis,the static elastic-plastic analysis and the dynamic elastic-plastic analysis.The calculation and analysis of different strengthen methods showed that the lateral stiffness of the structure strengthened by BRB and shear wall strengthen methods increases,the period decreased and the inter-story displacement decreased.Under the static elastoplastic analysis,the capacity spectrum curves and the inter-story displacement angles at the performance points of the three structures were obtained,as well as the plastic hinges of the structure strengthened by BRB and shear wall.The results showed that both strengthen methods could improve the seismic capacity of the structure.The BRB strengthen could effectively improve the development of plastic hinges,increased the redundancy of the structure,increased the seismic defense line of the structure and improved the seismic mechanism of the structure.However,the failure mechanism of plastic hinges of beams and columns strengthened by shear walls had not been improved very well under dynamic elastic-plastic analysis.Comparing the base shear force,interlayer displacement angle,vertex displacement and vertex acceleration of three structures under earthquake,the results showed that the braces of the structures strengthened with BRB entered the plastic working state under rare earthquakes,showing good hysteretic performance of the braces,consuming seismic energy,and the base shear of the structure decreased remarkably,while the lateral stiffness of the structures strengthened with shear walls decreased remarkably.With the increase of the base shear force of the structure,the seismic response of the structure also increased significantly.The analysis results showed that BEB could change the structure form of single-span frames,and the strengthen effect was more obvious and effective. |
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