DISCUSSION ON THE EQUILIBRIUM MATRIX THEORY AND STATIC AND STABILITY ANALYSIS OF A HYBRID SPATIAL STRUCTURE COMPOSED OF CABLES, BARS AND BEAMS

The equilibrium matrix theory in the analysis of cable-bar hybrid structures is discussed in this paper. For cable-bar hybrid structures the initial pre-stress distribution can be determined using the equilibrium matrix theory. The flexibility distribution of each cable or bar element should be considered at the same time. Bar elements with section sizes satisfying the flexibility distribution, can be used to construct the structure successfully eventually. A new method for flexibility distribution determination of cable-bar hybrid structures is proposed utilizing the compatible equation and the equilibrium equation. A new concept, independent flexibility distribution mode, is presented here. It is verified by a numerical example. In addition, a computational analysismethod of a hybrid structure composed of cables, bars and beams and its preliminary static and stability properties are presented in this paper. Based on the local analysis method the distribution and magnitude of pre-stress of this hybrid structure is analyzed using optimal theory. The outmost ring has larger pre-stress than the middle one and the inner one. Static and stability properties are analyzed by taking the pre-stress as self-equilibrium initial internal force. It is found that the flexible cable-bar system and pre-stress in the whole structure cannot reduce the deflection dramatically. But the pre-stress can affect the axial force distribution in beams very much. In comparison with single-layer reticulated shells this type of hybrid structures has high stability.