Abstract | Steel lattice towers are widely used by telecommunication companies to install radiowave dish antennas for the expansion of their network. They are tall highly-optimized structures for which severe weather conditions including low temperatures, snow and high winds are the governing loading conditions. Specifically, high winds in combination with accumulated ice on the members of the structure and the dishes are the leading causes of collapse. The focus is on a standardized model of a telecommunication tower used by major telecommunication companies in Greece. The model is designed according to European Standards for areas located at distances lower than 10km from the coastline. The tower is 48 meters tall, having a square cross-section whose dimensions generally reduce with height and it employs channel and angle steel sections. Non-linear dynamic analyses were performed in order to estimate the fragility of the structure to wind and/or icing conditions. Wind loads were simulated via a 3D wind field fully capturing the spatial and temporal variation of wind speed over the entire profile of the tower for different reference values of wind speed. The impact of ice was assessed by considering a range of different uniformly thick layers of ice that increase the weight as well as the cross-section area of all members and dishes. The ultimate goal of this work is to provide the fragility functions for every potential combination of wind and icing conditions that could be observed during the service life of the structure. Thus, by incorporating the corresponding climactic hazard surfaces, the risk of tower collapse is estimated over its entire projected lifetime, offering a useful decision support tool to telecommunication companies regarding the need to replace or upgrade their existing tower network on a caseby-case basis.

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