Analysis Of The Free Vibration Characteristics Of Tensioned Cable-Membrane Structures

As a new tentioned structure growing up in the mid of 20th Century and fast developing since then, membrane structure is widely adopted in both dometic and overseas projects. Compared with other tradiontional rigid structures, the outstanding characteristics of membrane structure are the use of materials which are financially cheap and light in weight, and the possibility to realise graceful architectural shapes, especially in large-spaced buildings, therefore membrane structure holds its irresistible appeal for the whole world.The processes of development, classification, characteristics, etc. of membrane structure are summarized, then such a novel structure as membrane structure is appreciated in architectural and environmental view. Different from traditional rigid structures, it is determined by the structural characters of membrane structure, that the form-finding and the analysis of free vibration characteristics of membrane structure are the key.By adjusting the span of strucuture, the ratio of height and span, the prestress and the tensile stiffness of membrane, and the tensile stiffness of cables, five main and important structural indexes which have great effects on the free vibration characteristics of structure, three typical tensioned cable-membrane structures, saddle-shaped membrane structure, conical membrane structure, and wave-shaped membrane structure, are systematically analyzed, and the results show:(1) the free vibration frequency is low and distributes in successtion;(2) the span of structure and the prestress of membrane have obiviously great effects on the free vibration frequency of structure, that the frequency decreases when the span increases, and increases when the prestress does. The span of structure has a negative impact on wind-resisting, but when the span is given, the free vibration frequency raises in a big amount if the prestress of membrane gets increased appropriately, which has a positive effect on wind-resisting;(3) the tensile stiffness of membrane and cable has little effect on the free vibration frequency of structure, especially on the 1^st free vibration frequency, accordingly it won't be effective to raise the free vibration frequency of structure by increasing or decreasing them.