Research On A Novel "Torus-Dome" Cable Strut Structure:Morphological Analysis And Anti-Collapse Performance Assessment

With the development of society,cable-strut structure,as a kind of newly arisen structure,is frequently applied to engineering project.Cable dome is one of the most representative types.However,ring beams are needed to support the cable dome structure for it can not achieve self-balancing.Based on the self-balancing property of tensegrity structure,this thesis puts forward a tensegrity torus structure to replace the function of ring beams.Combining a tensegrity torus with a cable dome,a new self-balancing cable-strut tensile structure,named torus-dome,is proposed.The finite element software and the vector intrinsic finite element method are applied to study mechanical properties of the structure,some beneficial conclusions are drawn.Through changing the geometry and topology of the classic half-octahedron tensegrity,a semi-regular tensegrity is put forward.Based on the singular value decomposition of the equilibrium matrix,a form-finding analysis of this semiregular tensegrity is presented.The thesis proposes design formulas for the unit geometric transformation to obtain its internal self-stress modes,inextensional mechanism modes and verify its geometric stability.Then,the thesis devises a design method and computes the overall feasible self-stress of a tensegrity torus.A novel self-balancing cable-strut tensile structural system is generated through combining a tensegrity torus and a Levy cable dome.Combining tensegrity torus with different cable domes,various torus-domes are generated and corresponding connection modes are advanced.In order to verify the feasibility of this structural system,several physical models are constructed.The vector intrinsic finite element method(VFIFE)is applied to study static and dynamic behaviors of torus-dome.During transition from initial state to morphological state and from morphological state to static state,internal force state of the structure is studied.The thesis finds the key components in forming process and explains the path of force transfer under vertical load.The parameter study including rise-span ratio,section area,prestressed level,outer ridge-cable angle is conducted.According to parameter study results,the effects on cable dome are explored when tensegrity torus stiffness is changed.Finally,some useful advice is drawn for structural design.Furthermore,the ration characteristic of structure is studied in finite element software AN SYS.Because of the advantage of the VFIFE in large deformation,large displacement analysis and other nonlinear analysis,this method is applied in the cable rupture analysis of torus-dome.Structural members are divided into tensegrity torus parts,transition connecting parts and internal cable dome parts.According to the responses after member rupturing,four failure modes are summarized.Based on the impacts failure members impose on the structure,structural members are classified in four groups,which are H-??H-??H-??H-? and S-I?S-??S-? from weak to strong respectively.Seismic time-history analysis of torus-dome is conducted under frequent earthquake and rare earthquake.Under different seismic intensity,X-directional seismic wave,Z-directional seismic wave and three-directional seismic wave are respectively applied to the structure.On the basis of the internal force responses and displacement responses,the sensibility of the structure under different seismic waves is contrasted.It is proved that the structure has good seismic performance.