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This paper investigates the use of the most fundamental elements; cables for tension and bars for compression, in the search for the most efficient bridges. Stable arrangements of these elements are called tensegrity structures. We show herein the minimal mass arrangement of these basic elements to satisfy both yielding and buckling constraints. We show that the minimal mass solution for a simply-supported bridge subject to buckling constraints matches Michell's 1904 paper which treats the case of only yielding constraints, even though our boundary conditions differ. The necessary and sufficient condition is given for the minimal mass bridge to lie totally above (or below) deck. Furthermore this condition depends only on material properties. If one ignores joint mass, and considers only bridges above deck level, the optimal complexity (number of elements in the bridge) tends toward infinity (producing a material continuum). If joint mass is considered then the optimal complexity is finite. The optimal (minimal mass) bridge below deck has the smallest possible complexity (and therefore cheaper to build), and under reasonable material choices, yields the smallest mass bridge. [ABSTRACT FROM AUTHOR]

Tensegrities are structures whose integrity is based on a balance between tension and compression. A numerical procedure is presented for the geometrical nonlinear analysis of tensegrity structures. This approach is based on a co-rotational method where the major component of geometrical non-linearity is treated by a co-rotational filter. This is achieved by separating rigid body motions from deformational displacements. The outcomes evince that the efficiency of the co-rotational approach is considerably greater than those using total Lagrangian and updated Lagrangian formulations for space rod elements, which have more rigid body movement modes than deformational modes. Numerical examples illustrate that the displacements of tensegrity systems depend on the applied force density coefficient and external loading values. Furthermore, in the analysis of tensegrity structures, constraints such as the yield strength of all elements and zero stiffness of string elements becoming slack at any equilibrium configuration must be allowed for. [ABSTRACT FROM AUTHOR]

This study investigates the structural performance of long and slender tensegrity booms. Previous studies show that tensegrity structures are generally more flexible than conventional trusses or space frames. The aims here were (i) to quantify how much more flexible eleven different tensegrity booms are, when compared to state-of-the-art truss booms, (ii) to find a general explanation for this. The performance criterion used for the comparison was the first natural frequency of the boom. A finite element program with truss elements was used to compute the natural frequencies around the initial prestressed configurations. The results show that tensegrity booms have between one and three orders of magnitude lower natural frequencies than truss booms. It is concluded that for the best performing tensegrity booms, the bending stiffness is independent of the level of pre-stress and the number of infinitesimal mechanisms as the bending stiffness is given mainly by the material stiffness of the tension elements and not the geometric stiffness as the infinitesimal mechanisms are not activated by bending. Thus, whereas the level of pre-stress and the presence of infinitesimal mechanisms play major roles for the stiffness of some tensegrity structures, the axial stiffness and orientation of tension elements are most important for the studied slender booms. [ABSTRACT FROM AUTHOR]

Tensegrity systems are structures made up of an assembly of pin-jointed pre-stressed continuous tension members (cables) and discontinuous compressive members (struts), arranged in different complex shapes. In the present study, static stability behaviour of plane double-layer tensegrity structures was investigated. Having verified the finite element modeling, several different collapse analyses were carried out in order to examine the instability behaviour of these tensegrity systems. Consequently, the different collapse mechanisms of the tensegrity systems were determined. In this study, the effects of the tensegrity configuration, the influence of the self-stress level, the effects of the post-buckling response of the "compression only" members and the post-yield response of the "tension only" members were investigated. Based on the obtained results, some important conclusions have been drawn and some design recommendations are put forward to prevent the occurrence of the dangerous collapse mechanisms. [ABSTRACT FROM AUTHOR]