Elastic-plastic Stress Performance Study Of K-eccentrically Braced Steel Frame

Eccentrically braced steel frame structure based on concentrically braced frames.Underthe rare earthquake action，dissipative link of an eccentrically braced frame becomes plasticearlier.Then it consumes the energy of earthquake by its plastic buckling deformation. It is aideal high-rise steel structure of resistance to lateral force system.With the continuousdevelopment of economy and the steel structure industry in China,the application ofhigh-rise eccentrically braced steel frame structure is also more and more.In order to providetheoretical guidance for engineering practic,the elastic-plastic stress performance of the Kshape eccentrically braced steel frame structure were studied in this paper.For the K shape eccentrically braced steel frame the finite element numerical simulationanalysis is finished by finite element software sap2000.Considering the different length oflink beam,different height-to-thickness ratio of web,different slenderness ratio,differentlayouts of brace and differen pitch of Structure and establishing27overall models,performance point determination,the floor displacement, the interlayer displacement,and thedevelopment of the plastic hinge were studied.Research results show that.Under the action ofthe earthquake,the dissipation beam section of eccentrically braced steel frame buckling andreduce much seismic energy.It has the very good ductility and seismic performance.Suggested that the eccentrically braced steel frame should be used firstly in the practicalengineering.When the dissipative link is too long,the whole lateral stiffness of the structure issmall and earthquake displacement reaction is large.When the dissipative link is too short,thewhole lateral stiffness of the structure is big and it absorb more seismic energy.Suggested thatthe length of the energy dissipation beam section is between1.1M p/Vpand1.3M p/Vp.Itmainly rely on the web shear yield of the energy dissipation beam section for energyconsumption.Suggested that the web thickness ratio of the energy dissipation beam is between35and55.When the support slenderness ratio is large,it buckling easily and reduce the energydissipation performance of structure.When the Support slenderness ratio is small,The integrallateral stiffness and earthquake force is big.Suggested that the support slenderness ratio is between30and37.The reasonable staggered arrangement of the energy dissipation beamsupport can improve the whole lateral stiffness of the structure and the seismic performance.Suggested that the Support arrangement adopt reasonable staggered arrangement form.Whenthe depth-span ratio of Structure is small,the whole lateral stiffness of the structure is largeand the energy dissipation is poor.When the depth-span ratio of Structure is large,the ductilityof structure is good and the bearing capacity is small.Suggested that the depth-span ratio ofStructure is between0.5and0.8.