Basic Research On The Static Analysis In Tensegrity Bridge

Tensegrity structure is a kind of special spatial structure which is a combination of continuous cables and discontinuous struts. Its stability is provided by the sel-stress in cables and struts. The fully used of the material makes the lighter weight of the structure and the continuous cables and discontinuous struts make the structure a splendid mould, therefore tensegrity structure is widely used and more and more researchers are attracted. A complete research of a tensegrity structure comprises form-finding, implemetation of self-stress and the analysis of behavior under external loads. Given little research on tensegrity structure, this thesis particularly analyzes form-finding, the tangent stiffness, the stability and analysis of the tensegrity structure.Firstly, this thesis reviews the history of tensegrity structure, and makes a summary of the existing form-finding method. For a special tensegrity: a type of tensegrity prism, a new kind of form-finding method has been proposed which was based on minimal of balance residual and the coordinates of the nodes and the type of bars. Then implementation of this form-finding method procedures calculated the corresponding force densities of two-dimensional tensegrity sturcture, a triangular prism, a quadrangular prism and a pentagonal prism which made the structure self-stress and self-balanced.Secondly, this thesis made theoretical derivation of the expression of the tangential stiffness matrix of tensegrity structure, and took tangent stiffness of two-dimensional tensegrity analysis for example to discuss the impact of structural materials and self-stress levels on tangent stiffness. Then stability analysis of prismatic tensegrity structure was explained, and two methods to determine the structure stability were introduced. in the end, the two-dimensional tensegrity structure was as an example to discuss whether it met stable conditions.Thirdly, the research on structure analysis was done. This thesis chose two ways: a vector space method provided by Pellegrino and a finite element method. Taking an example of a two-dimensional tensegrity structure and a triangular prism, the structural response has been calculated.Finally, the details of a special form of tensegrity footbridge was introduced through establishing the model and the tensegrity module which was composition of the bridge, and then the vector space method which was programmed by direct stiffness method was used to calculate the bridge response under distributed load; and the maximum stress of tension members in the structure under different levels of uniform load was calculated to examine constitutive relations of the structure; then structural influence lines of four typical structural members has been drawn to analyze the reaction of the bridge under live load, which provides the analysis of the tensegrity footbridge a reference.