Failure Mechanism And Catastrophe Control Of Cylindrical Shells With The Consideration Of Substructure Under Severe Earthquakes

The single-layer cylindrical shell is a common form of spatial structure with vast potential of future development.It is utilized widely and developed rapidly in recent years due to the good integrity,the light weight,easy assembly and aesthetic beauty.Research work on large span spatial reticulated shells was mainly focused on dynamic behaviors,stability analysis,buckling and path tracking,elasto-plastic large deformation simulation and failure mechanism under severe earthquake.Most of the studies were based on the simplified analytical model that is installed directly onto the ground by pin for the purpose of simplicity.In fact,spatial cylindrical shell are usually supported by substructures which are supported by foundation.There will be some deviations in the numerical simulations without the consideration of the influence of substructure and soil.Therefore,according to these practical problems,the failure mechanism and failure control method of cylindrical shell with consideration of substructure is studied systemically in this paper.The main research contents are stated as follows:1.Analysis of natural vibration characteristics of cylindrical shell considering the influence of supporting stiffnessSupporting stiffness is an important factor which affects the dynamic characteristics and the failure characteristics of structures subjected to severe earthquakes.The natural vibration behaviors are the inherent characteristics of the structure which greatly influence the ultimate load of reticulated shell under severe earthquake,Therefore,it is significant to analyze the natural behaviors of reticulated shells with different supporting stiffness.In this paper,the influence of supporting stiffness upon natural behaviors of reticulated shells is analyzed systematically.In order to facilitate the analysis,the effects of different sizes of steel columns on the natural vibration characteristics are studied in this paper.Firstly,the ABAQUS software is used to establish the analysis model of the reticulated shell and the substructure,The supporting structure is assumed to be elastic.The constitutive model of material with damage accumulation of cylindrical shell is established by the ABAQUS user material subroutine(UMAT).Then,the natural vibration behaviors of cylindrical shells with different supporting stiffness are analyzed.The influence of different sections of steel columns on the natural vibration behaviors is analyzed.Finally,the influence of structural parameters(rise-span ratio,the length-width ratio,the roof load,et.al)of cylindrical shells upon the natural vibration behavior is analyzed.2.Failure mechanism of cylindrical shells with the consideration of substructure subjected to severe earthquakesIn this paper,the incremental dynamic analysis(IDA)is carried out to analyze the failure behaviors of reticulated shells with substructures.Firstly,through a large amount of analysis examples,failure modes of reticulated shells with the strong and weak substructure under severe earthquakes are summarized.Secondly,the seismic failure analysis of single-layer cylindrical shells with different substructure systems is carried out.The failure characteristics of single-layer cylindrical shells with different substructure systems are recorded.By means of statistical analysis,the ultimate load and the damage degree of reticulated shell structure are determined by the failure discrimination criteria.Finally,the influence of structural parameters(span ratio,the length-width ratio,the roof load,et.al)of single-layer cylindrical shell upon the failure characteristics is summarized by a large number of analyses.3.Catastrophe control of latticed cylindrical shells with buckling restrained brace subjected to severe earthquakesBuckling restrained brace(BRB)is widely used as a new type of energy dissipation brace,in order to improve the seismic performance of structures and to reduce the damage of structure under severe earthquakes.In this paper,the catastrophe control of single-layer latticed cylindrical shells by utilizing buckling restrained braces subjected to severe earthquakes is studied systematically.Firstly,characteristic responses of single-layer latticed cylindrical shells without braces,with common braces and with bucking restrained braces in the substructure are investigated.Catastrophe control mechanism and effect are illustrated by a series of parameter analysis.Secondly,through the statistical induction of typical examples,three structural failure modes of single-layer latticed cylindrical shells with bucking restrained braces in steel substructure are illustrated.Finally,the influence of parameters including the area of bucking restrained braces,yielded strength,size of the substructure,rise-span ratio of reticulated shell,arrangement of bucking restrained braces within the substructure on catastrophe control mechanism is illustrated.This paper also puts forward the reasonable section area value of buckling restrained braces.