Experimental Study On The Influence Of Shear Span Ratio On The Failure Of Vertical Members

The failure of vertical components is the main cause of structural collapse under earthquake.Column and wall are the main representatives of vertical members.Seismic damage investigation shows that shear span ratio is closely related to the failure of vertical members.Based on the shear span ratio as the breakthrough point,through model experiment,numerical simulation and theoretical analysis,this paper discusses the influence of shear span ratio on the seismic failure mode of vertical components in several typical structures.The research results will serve for the study of seismic collapse mechanism of structures.The main research work is as follows.1.The constitutive model and failure mode of pure frame structure model are studied,which are used as the comparison standard of mechanical effects of other construction methods.2.The constitutive and failure modes of the structural models of masonry-infilled wall and masonry-infilled wall are studied.The results show that compared with the pure frame,the constitutive model of the first masonry wall shows obvious high-steep characteristics,and brittle shear failure occurs when the lateral displacement is small,and then the masonry wall model is between the first masonry wall model and the pure frame model.3.In order to simulate the actual earthquake damage,the constitutive model and failure mode of wide-narrow composite vertical members are studied,and the influence of shear span ratio on the failure mode of vertical members is discussed in the most direct way.The results show that under the same interlayer displacement,the smaller the shear span ratio is,the more unfavorable the shear is,and the failure of shear mode occurs first.The above research shows that the vertical load-bearing members in the small shear span ratio state because their own structure or infill wall constraints result of,which is very unfavorable for seismic resistance.On the one hand,the lateral stiffness is significantly improved,which is easy to cause ’ internal force condensation ’.On the other hand,the ductility is greatly reduced,which is prone to brittle failure and causes the overall collapse of the structure.