Analysis Of Seismic Performance Of Controlled Rocking Steel Braced Frame System

After a brief review of the frontier development of the controlled-rocking self-centering structures,carried on the finite element simulation experiment,and according to this method of simulation,established three and seven layers structure model.The ground motion records were selected with method which is based on the thesis of the bands to choose the right records for the time-history analysis.Seismic performance of this structure system were made clear under small earthquakes and major earthquakes through the combination of the study of theory and simulation.Main conclusion are listed as follows:1)Through the reasonable design,the controlled-rocking self-centering structures uses its rigid rotation,driving the butterfly-shaped walls between the two frameworks,and by post-tensioning strand providing the restoring force,ensuring structure can revert to the original position after the earthquake,to realize "small earthquakes not bad,repairable,in strong earthquakes is less than" fortification goal.2)Controlled-rocking self-centering structures is mainly related to post-tensioning strand and butterfly-shaped walls collaborative working relationship,and this kind of collaborative working relationship is characterized by the self-centering ratio.The greater the reduction rate of structure in the smaller residual deformation after the earthquake,but the energy dissipator energy dissipation effect is poorer,so choose appropriate self-centering ratio is very important.With different self-centering ratio structure system are analyzed,and the double controlled-rocking self-centering structure is obtained,the self-centering ratio of the reasonable range of values between 0.5 ~ 1.5 is more economic and reasonable.3)In this paper,seismic performance research of the three and seven layers controlled-rocking self-centering structures are made clear,concluded structure performance goals are as follows:(1)In normal use phase,column feet don’t lift,similar to hinged column feet node at this time,frame stiffness on its own level of lateral load resistance,vertical force transmission path of the structure for the plate-beam-column;(2)Under small earthquakes,column foot can occur slightly raised,lift height is not more than two over one thousand of the total height structure,the top displacement ratio and the largest displacement angle between the layers of not more than 0.4%,the butterfly-shaped walls do not produce plastic deformation,structure hysteresis curve hysteresis loop back;(3)Under moderate earthquake,column foot is raised,in some earthquake ground motion,the butterfly-shaped walls can produce certain plastic deformation,the hysteresis curve of the structure is kneading,but post-tensioning strand does not produce plastic deformation,top floor displacement ratio and the largest displacement angle between layers of the structure are not more than 1.5%;(4)Under severe earthquake,the structure column foot is raised,the butterfly-shaped walls can produce large plastic deformation,hysteretic curve of the structure is full,post-tensioning strand still does not produce plastic deformation,maximum displacement ratio and the displacement angle between layers of the structure are less than 2.0%.