Dynamic analysis of guyed towers subjected to wind loads incorporating nonlinearity of the guys
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Guyed masts are unique civil engineering structures, structurally efficient, selfsupporting lattice towers. High structural efficiency of guyed towers is achieved by the use of pre-tensioned cables and a skeletal design. The height of guyed masts can exceed 600m (Sparling, 1995), therefore they are extensively used by telecommunication industry. Guyed towers also have the highest failure rate. Since 1959, there have been 100 confirmed collapses of guyed towers in United States (Madugula, 1998). Failure of guyed tower results in significant economic loss and human inconvenience. This report emphasizes on the study of guyed towers subjected to dynamic wind loads. A schematic of guyed tower is shown in Figure 1.1. Typically the guyed mast is constructed as a triangular space truss with warren or cross-praced configuration. The mast is pinned or fixed at the base while the top usually supports an antenna. Pretensioned cables, radiating symmetrically from the mast at several elevations, provide lateral support to the mast. Traditional techniques for the analysis of guyed towers rely on pseudo-static analysis and are insufficient because of significant secondary effects and nonlinear behavior of cables. Due to overall flexibility, slendemess and lightweight, guyed masts are susceptible to large deflections and also exhibit high dynamic sensitivity to turbulent winds. As a result, dynamic analysis is considered imperative for calculating the peak axial forces in the mast. Other environmental factors like icing and snow accumulation on cables can significantly enhance the mast response, sometimes resulting in structure failure.