Theoritical And Experimental Research On The Large-Span Annular Open-Web Cable Truss Structures

The large-span annular open-web cable truss structure is a new type of tensile structure based on cable dome. Especially it is suitable for awning structures of palestra. Little research work on this type of structure has been done abroad, and at home the research is blank. With the development of Chinese physical culture, more gymnasiums are required to be constructed. Some theoretical and experimental discussion of this kind of structure is presented in this paper, which majors in its static and dynamic property, and aims at its earlier application in domestic gymnasiums.First, based on the reading of a lot of literatures, a view of the history of tensegrity structures and cable dome structures is put forward in this paper, as well as the expatiation of the architectural and structural property on the large-span annular open-web cable truss structure. Several projects are also presented. After summarizing the research actuality about this kind of structure (mainly about cable dome),the research contents of this paper are presented.As this kind of structure system is a self-equilibrium system, it is necessary to make it clear of the distribution of self-equilibrium stress. By using the singular-value-decomposition method, a little program has been developed to get the self-equilibrium stress mode of several typical cable truss structures. Elicited by the computational results, the relationship between the internal force and the length of masts is found and proved. Moreover, for asymmetric structure by the horizontal axis, when the annular cable is horizontal, the same scale of the two parts (upward and downward) of all masts must be satisfied.The geometric nonlinear analysis of three types of large-span annular cable truss structures is put forward by using commercial FEM program. Their static properties in deferent load case are concluded, and some suggestions for actual projects are also presented.Base on the prime realization of its static property, parameter analysis of its static property is done consisting of deferent number of truss, deferent height of truss, deferent scale of height of masts, deferent boundary condition and deferent magnitude of pre-stress in deferent load case. At last, some conclusion has been obtained. Atpresent the effect of cable and its pre-stress is not very clear. Based on the rule of conversation of energy, it is proved to be right in theory that the stiffness of the linear elastic structure is larger with the increase of its pre-stress.After the static analysis of this type of structure, the optimal system is discussed in this paper and another new kind of cable-truss structure similar to Levy cable dome is put forward. The analysis proves that this type of cable-truss has excellent static property.The free vibration property of cable-truss structures is analyzed, as well as the parameter analysis. It is obvious to see the remarkable improvement of the frequency, however the scale of the height of masts has little effect on frequency. On the contrary, increasing the number of support has remarkable effect.To get its seismic property of annular cable-truss structure without support, time history analysis is done to show that it is not effective to control the seismic property with modifying the magnitude of pre-stress. All results shows that the new kind of structure mentioned in this paper has good mechanical property for widely application.At last, for direct realization of this kind of structure system, an experiment of cable truss structure with D5 and 16 trusses has been done to check its distribution of self-equilibrium stress. At the same time the static property test with deferent value of pre-stress, deferent kinds of load cases has been also done, the 8-order frequencies have also been obtained. All test results consistent with the theoretical analysis. It is proved to be right of the analysis method and the results of this paper.Finally a conclusion has been made to point out the lack of this paper and the problem for further research.