Study On The Seismic Performance Of Single-layer Spherical Reticulated Shells With A Lower Separated Support System

Single-layer spherical reticulated shell structure is a kind of large-span space structure which attracts much attention at home and abroad and has broad development prospects.It is widely used in stadiums,airports,Convention and exhibition centers and various large assembly venues.In this paper,the seismic behavior of a single-layer spherical reticulated shell structure with a lower partially detached support system(which divides the lower support structure into steel structure support which can withstand the horizontal and vertical loads of the roof and concrete support structure which only bears the vertical loads of the roof)is studied in depth based on the refined modeling method of beam-column fiber unit.This paper mainly does the following three aspects:(1)Using finite element software ABAQUS,the single-layer spherical reticulated shell structure model supported by steel column using double-folded line followup reinforcement constitutive model and Giuffre-Menegotto-Pinto constitutive model are established respectively.By extracting maximum combined displacement of joint,displacement time-history curve of typical joint and stress time-history curve of typical bar,two different constitutive models are studied for three different vertical-span ratio structures in three places.Effect of seismic response of structure under vibration.The research shows that the maximum combined displacement of single-layer spherical reticulated shell structure using double-fold line followup reinforcement constitutive model is smaller than that using Giuffre-Menegotto-Pinto constitutive model,and the displacement time-history curves of single-layer spherical reticulated shell structure using double-fold line followup reinforcement constitutive model and Giuffre-Menegotto-Pinto constitutive model at points N1,N2 and N3 are calculated based on the structural level.The variation trend is approximately the same,but the peak displacement of the structure with double fold line followup reinforcement constitutive model is always smaller than that of the structure with Giuffre-Menegotto-Pinto constitutive model.This shows that the two constitutive models have certain influence on the displacement time history of specific joint,but have greater influence on the structural displacement peak value.Although the change trend of the section positive stress time history curves of two members based on different constitutive models is approximately the same,their peak values differ greatly,and the stress peak value of members based on Giuffre-Menegotto-Pinto constitutive model is larger than that based on double folding line follow-up strength.Bar elements for the constitutive model.This shows that the two constitutive models have certain influence on the sectional normal stress time history of certain members,but have greater influence on the peak stress.Referring to the conclusions of comparative analysis of the two constitutive models based on the member level,and combining the research in this chapter,it is recommended that the Giuffre-Menegotto-Pinto constitutive model be used in the seismic analysis of single-layer spherical reticulated shell structure.It is not recommended to use the Giuffre-Menegotto-Pinto constitutive model.Double folded line followup reinforcement constitutive model.(2)By comparing and analyzing the seismic response of two different lower support structures,i.e.the lower partially separated support system and the lower concrete support system,under different ratio of rise to span,the maximum combined displacement of joint,the maximum horizontal displacement curve of the top of concrete column and the stress timehistory curve of typical bar are extracted,and the design of concrete column is repeated by comparing the corresponding support reaction changes.The differences of mechanical properties between the two structures were studied.The research shows that under the same design conditions,the maximum joint displacement of the structure with lower concrete support system is always smaller than that of the structure with lower partial support system under the same peak acceleration due to the reduction of the horizontal stiffness of the structure with lower partially separated support system;for the two different structures with lower support system,with the ratio of rise to spanThe maximum combined displacement of joint increases gradually with the decrease of bearing mode,and the change of lower support mode has certain influence on the stress time history and peak stress of steel and concrete members.The change of the ratio of rise to span has certain influence on the stress time history and stress time history and stress peak value of steel members in the structure with lower concrete support and in the structure with lower partially detached support,but has little influence on the concrete column in the structure with lower partially detached support;because the top level of structural concrete column with lower partially detached support system is horizontalThe release of shear and bending moment greatly reduces the shear and bending moment at the bottom of the concrete column,which allows the concrete column to bear greater peak acceleration with smaller section area and reinforcement ratio and higher safety reserves.(3)Three kinds of steel structure supports with different stiffness and three kinds of concrete support structures with different stiffness are used in two groups to study the effects of different lower support stiffness on the seismic behavior of single-layer spherical reticulated shell structure with lower partially detached support system,and to summarize the general rules of influence of lower support stiffness on the overall structure.The research shows that for single-layer spherical reticulated shell structure with lower partially detached support system,the maximum joint displacement is mainly affected by the support stiffness of steel structure,and decreases with the increase of support stiffness of steel structure.However,the change of stiffness of concrete supporting structure has little effect on the maximum combined displacement of joint,which indicates that the interaction between concrete supporting structure and steel structure support is small;when the support stiffness of lower steel structure is the same,the maximum horizontal displacement of joint of concrete column top decreases with the increase of diameter of concrete column and reinforcement;when the support stiffness of concrete remains unchanged,only steel is changed.The maximum horizontal displacement of the joint on the top of the concrete column remains unchanged with the structural support stiffness.