Research On Seismic Response Modification Factor Of High Strength Steel Composite K-type Eccentrically Braced Frame

High strength steel composite K-type eccentrically braced frame is a new anti-seismic structural system.The system combines the advantages of the concentrically braced steel frame with the advantages of the pure steel frame which has well lateral stiffness,structural strength and energy dissipation capacity,and with the use of high strength steel,the steel usage will be reduced,which has good economic benefits and application foreground.The seismic response modification factor is a significant factor which is widely applied in the medium earthquake design method in foreign countries to determine seismic action.However,the method that determines designed seismic action based on probabilistic method in current Chinese seismic code not involves the clear value of the seismic response modification factor.The research on seismic response modification factor of the new system in this paper mainly has done the following work.Firstly,4 groups of 16 high strength steel composite K-type eccentrically braced frames were appropriate designed using Sap2000 finite element software according to Chinese codes and the existing research results of high strength steel material,which considered the influence of stories,the height-span ratio,the length of active beam link and the different steel strength.Through the comparison of finite element result and the early test of research group,verified the correctness of modeling.Secondly,all structures were carried out nonlinear static analysis through Pushover analysis and obtain the displacement of roof story-base shear curves of each structure.The Pushover curves were transformed into capacity curves based on the improved capacity spectrum method and considering the influence of high order mode and the spectrum curve was transformed into elastic-plastic demand spectrum,then the structural behavior point was confirmed.Proceed to the next step,it can calculate the seismic modification factor,the structural overstrength factor,the structural ductility factor and the displacement amplification factor.Next,the influence of different parameters was analyzed and the suggested values of the seismic modification factor and the displacement amplification factor were provided.Immediately following summarized the current design method abroad and the use of the seismic modification factor.In combination with the results in this paper,the design method is provided which is suitable for our code,based on the seismic modification factor.Finally,according on the design method of this paper.In order to verify the rationality and applicability of this paper’s result,choosing 4 structures previous were redesigned and new structures were conducted the elastic-plastic analysis based on the Chinese seismic code to.Then the economy was compared with the ordinary strength steel results.