Study On Tensegrity Footbridges Based On Ring Modules

Tensegrity systems are spatial structures composed of a discontinuous set of compressed components and a continuum of tensioned components in a self-equilibrated state of self-stress providing stability to the structure.Tensegrity structures have already been studied in various fields over the past decades,due to elegant modeling,light weight and clear force.Among them,a kind of ring tensegrity module is widely concerned in the engineering field because of its excellent bending resistance.Through the front-to-back connection between the modules,a ring footbridge structure with internal passage space can be formed.As a kind of tensegrity structure,the first thing we need to do is to find out a kind of initial prestress distribution which can meet the requirements when the node location and the component topological connection have been determined.In addition,in the structural design,it is necessary to adjust the value of key parameters in order to achieve the purpose of efficient control of structural performance.Therefore,it is of great significance to obtain the important parameters that affect the structural performance.Joint design has always been one of the most important work in the development of tensegrity structure in the field of engineering application.The feasibility and reliability of the joints will directly determine whether the structure can finally land in the actual projects.In order to solve the above problems,this paper will make an in-depth study on this kind of footbridge structure based on ring tension integral element on the basis of previous research work.The system analysis of the tensegrity modules is carried out,and the component classification of the element is re-divided according to the prestressed mode.The concept of overall feasible prestress is introduced into the process of force finding of basic modules.The self-stress mode of the model is calculated by the equilibrium matrix theory and singular value decomposition(SVD),and then the self-stress combination coefficient satisfying requirements is obtained by a feasible method.The performance analysis of the structure composed of ring tensegrity modules is carried out.By means of the control variable method,three kinds of structures with different configurations,which are composed of quadrilateral,pentagon and hexagon modules,are studied the influences of the cross-section area of five classes of members and the overall prestress level on the static and dynamic performance of the structure are studied.In the process of research,a kind of structural parameter which has significant influence on the stiffness and strength of the structure is found out.This discovery is helpful for designers to adjust the structural performance efficiently in the process of structural design.An improved structural efficiency index is proposed to evaluate the structural efficiency of the ring tension integral footbridge structure.Combined with the results of structural performance analysis and previous studies,the original structural efficiency index is improved.The improved structural efficiency index corrects the problem that the proportion of structural stiffness in the original index is too high,and verifies the reliability of the new index by comparing with the existing research results.In addition,it is found out that in addition to the basic unit configuration,the number of units is also an important parameter affecting the structural efficiency.The table of module recommended numbers of three configurations in common scale is established.Based on the results of structural efficiency analysis,combined with the requirements of internal traffic space and the commonly used span of the project,the module recommended numbers table of three configurations is given under the commonly used scale.Under the given project situation,the trial design of the structure is carried out based on the previous research and relevant standards and specifications.a kind of hollow hemispherical joint is proposed.This kind of joint can connect the struts and the cables at the same time,and also can be connected with each other,which meets the requirements of structural assembly construction.The work of this paper improves the theoretical research of the ring tensegrity module,and provides the key information and methods needed in the structural design process of the footbridge structure based on the ring tensegrity module,which is helpful to promote the practical application of the tensegrity structure in the engineering field.