Research On The Structural Design And Construction Integration Of Tensile-Beam Cable Doom

Cable dome is a kind of spatial cable-strut structure composed of the ridge cables,oblique cables,hoop cables and struts.It was highly valued by the academic field of the international spatial structure and the field of engineering application with its novel structure,smart conception,lighter weight and rapid construction.In recent years,the roofing system of the cable dome structure is mainly made of tensioned membrane.The study of rigid-roof cable dome is still in its infancy.Traditional rigid roofing material,such as glass panel,color steel plate,has been extensively applied in domestic steel roof structures.However,the spanning capacity of the rigid roof is poor,and thus,substructure is needed to support the roof plates and transfer the roof load to the main structure of cable dome.In this case,the spanning capacity of substructure must be strong enough.Suspen-dome structure is a kind of hybrid structure with both hardness and softness.In suspen-dome,the ridge cable network is replaced with rigid reticulated shell,which makes it easily to lay rigid roof plates.However,due to the compressed and bended reticulated shell,the steel consumption is large.In addition,a large number of stents are needed to support and install the suspen-dome at high altitude.As a result,the construction cost is high,the amount of welding work is large,and the construction period is long.Based on existing literatures at home and abroad,this paper analyzed and summarized the structural characteristics,construction technologies and engineering applications of both conventional cable dome and suspen-dome,and proposes a new structure called a tensile beam-cable dome(TBCD).TBCD consists of oblique cables,struts,ring cables,and tensile ridge beams,which replaces the ridge cables of the traditional cable dome with hinged beams that can bear both tensile and flexural effects.TBCD has the advantages of both conventional cable dome and suspen-dome.By building prestress in tensile beams,oblique cables and hoop cables,the whole structure is a kind of tensegrity structure.Tensile beams can bear both tensile effects and flexural effects,this makes it convenient to lay rigid roofing materials on.Furthermore,several joints between tensile beams and other members are hinged,which is helpful in preforming the less-bracket or even non-bracket tow-lifting construction method to build the whole structure,and can improve the stability of the whole structure.The configuration of TBCD and its basic composition are presented.Two kinds of hinges can be set on tensile beams,namely the structure hinges at the two ends and the mechanism hinges in the middle.According to the distribution of hinges,TBCDs can be divided into four types:non-hinge TBCD,single-hinge TBCD,double-hinge TBCD and three-hinge TBCD.A comparative analysis is performed to compare the force transfer mechanism and deformation response among three-hinge tensile beam,two-hinge tensile beam,single-hinge tensile beam,middle-hinge tensile beam,non-hinge tensile beam and ridge cable under two loading conditions.After that,the iteration method is introduced to conduct the force-finding analysis of a numerical model.In addition to achieving the aims of non-bracket tow-lifting construction,the integral tow-lifting method is adopted,and the nonlinear dynamic finite element method(NDFEM)of form-finding analysis is improved for the overall construction analysis of TBCD.For integral tow-lifting construction,fourteen forms of TBCDs with different setting modes of joints are put forward to transfer the tensile beam network to mechanism.Through construction analysis of these forms of TBCDs,the feasible and optimal modes of tensile beams are found out.Nonlinear finite element method is used to analyze the static properties of TBCD.The variations of internal forces and nodal displacements of TBCD under full-span and half-span conditions are calculated,and the effect of fix mechanism joints of tensile beams are compared.Considering the structural differences of suspen-dome,conventional cable dome and TBCD,three numerical models are built with same span and topology for these three structures.The comparative analysis are conducted,and the effect of rigid tensile beams to overall stiffness,local stiffness and bearing capacity are found out.Furthermore,parametric studies are carried out to test the effect of pre-stress level,changing of temperature and section form of tensile beam.After that,a dynamic analysis is also performed to compare the vibration characteristics of these three structures.Linear buckling analysis is carried out to find and compare the eigenvalues of suspen-dome,conventional cable dome and TBCD under full-span and half-span loading conditions.Then,the consistent mode imperfection method is introduced,the first order buckling mode is set as the imperfection distribution,1/300 of the structural span is set as the maximum value of the imperfection,and the nonlinear buckling analysis is conducted to find the ultimate bearing capacities of these three structures.After that,the effects of pre-stress level,sectional specification of tensile beams,maximum value of imperfection and ring beams are discussed.A 6 m Geiger-typed TBCD experimental model and an 8 m Levy-typed TBCD experimental model are designed to check the results of FE analysis above.The compositions of components,the forms of joints and the installation process are described at first.Then,the construction process is simulated,and the internal forces and displacements are measured,which verified the feasibility of non-bracket tow-lifting construction method for TBCD.After that,the mechanical properties of these two models are tested under full-span loading condition and half-span loading condition.By comparing the results of test and numerical simulation,some useful conclusions are obtained.Finally,a systematic conclusion of the research contents and results are draw,then,some key problems to be solved in further research are put forward.The studies in this paper give important basis in theory research and engineering application of structural design and construction of the TBCD system.