Modeling Non-Linearity on Cable Stayed Masts of Tensile Fabric Structures

Tensile membrane structures are part of a unique technology that gives designers the capability to experiment new forms and new solutions to conventional design problems. These structures are extremely efficient for long span application and allows considerable savings in the foundations and supporting structure costs. Cable stayed masts are integral part of this structure typology and consists of a inclined elements supported by several layers of pre-tensioned cables. Generally their dynamic loading is not a concern in the design of tensile structures, nevertheless in case of massive shafts, their dynamics can play a fundamental role for global behaviour of the structure. Therefore pre-tensioning force on supporting cables system is an important issue since the internal force distribution, significantly affects their structural dynamic behaviour. A non-linear cable model, combined with the taut-cable theory has been employed to simulate the non-linearity conditions in the stays and cables, by using a restoring-force equivalent spring model to replicate the behaviour of each cable. In the present paper a simplified based displacement technique is utilized to examine the non-linear dynamics of the system. The proposed approach, based on energetic method Equivalent Linearization method (ELM), shows a robust simplified technique capable to linearize the non-linear system, taking into account of slackening effects of pre-tensioned stays. It is concluded that performance coefficient and linearized frequency, may possibly be used as useful indicators for designing pre-tensioned cable stayed masts where a suitable selection of the initial pre-tensioning force can effectively improve dynamic performance of the system.