Innovative solutions for design and strengthening of telecommunications and transmission lattice towers using large angles from high strength steel and hybrid techniques of angles with FRP strips.

ended

Angle sections are extensively used in lattice towers and masts for telecommunication or electricity transmission. In addition, single or built-up sections made of angles are used in a wide field of civil engineering applications including buildings, bridges or for strengthening existing structures. However, there is a lack of consistent European rules for design for members made of angle profiles. Recent developments have led to a wider application of large angle sections made of high strength steel, for which European design rules are missing. Due to increasing loads, strengthening of existing towers, especially for communication, is an issue faced in everyday practice. However, design codes cover only one specific configuration. The objective of this proposal is the development of design rules that exploit the carrying potential of angle sections, including large angles from high strength steel, the improvement of existing rules for built-up sections and the incorporation of innovative types of built-up sections composed of two angles with unequal sections. In addition, hybrid profiles composed of angle sections and FRP plates will be investigated and relevant design rules developed. Such hybrid members provide innovative and cost effective solutions for strengthening existing lattice towers. Experimental and numerical investigations will be performed at the level of cross sections, members, as well as of structural tower sub-assemblies to incorporate the influence of realistic connection conditions, existing eccentricities and load shedding between tower walls. Case studies will be examined and a performance-based assessment of the actual system safety will be conducted incorporating uncertainties in loads, material and geometry. A comprehensive evaluation of the reliability infused by the new design rules will be made. The proposed rules will be integrated in design software for towers.