| description abstract | A triangular configuration is preferred over square configuration for communication towers due to significant weight reduction and less space for installation. Using 60° angles as leg members in triangular towers will facilitate the connection between the leg and bracing members, evading the use of bent-up gusset plates. The 60° angle sections are stronger in flexural buckling but weaker in torsional-flexural buckling. In this paper, experimental and numerical investigations are conducted at the component and structural levels to evaluate the torsional-flexural buckling behavior of 60° angle sections. Component-level experimental experiments, including material characterization and geometric imperfection studies, have been carried out on two types of typical 60° angle sections, such as v110×110×10 mm and v80×80×6 mm, with varying effective lengths, such that these sections fail in torsional-flexural buckling mode. Numerical investigations using nonlinear FEA software have been carried out for validation with experimental and ASCE/SEI 10-15 code buckling strength predictions. Full-scale prototype test conducted on a 5.5 m high roof-top triangular communication tower with antennae loads. The tower is fabricated using 60° angle leg members and conventional 90° angle sections for all other members. The leg member failed in torsional-flexural buckling mode, similar to component-level test results. Based on the numerical investigation, the structural performance in terms of deflection and self-weight is found to be 30% and 10% less when compared with similar triangular tower configuration subjected to same load using a 90° angle section as leg member with bent-up-gusset plates. Further, a comparative numerical investigation study carried out to examine the behavior of 60° angle sections at the structural level conducted on two numbers of a 24 m high triangular communication tower made of 60° and 90° angle sections, respectively, as leg members, designed for same wind speed and antennae loading. The deflection and self-weight of the 24 m high triangular tower made of 60° angle section as a leg member are 40% and 16% less compared with the triangular tower made of a 90° angle section as a leg member with bent-up gusset plates. This paper emphasizes the advantages of using a 60° angle section as a leg member in triangular-based communication towers compared with the triangular tower made of a conventional 90° angle section as a leg member with bent-up gusset plates. Using 60° angles as leg members in triangular towers will facilitate the connection between the leg and bracing members, evading the use of bent-up gusset plates. Based on numerical and experimental investigations, the structural performance in terms of deflection and self-weight is compared for two types of triangular-based communication towers made of 90° and 60° angle sections as leg members subjected to similar antennae and wind loads. For triangular towers made of conventional 90° angle sections with bent-up gusset plates, the deflection is 30%–40% higher than the 60° angle tower due to out-of-plane deformation of bent-up gusset plates in the connection region. The self-weight of the triangular tower with conventional 90° angle sections as leg members with bent-up gusset plates is 10%–16% higher than towers with 60° angles due to the additional weight of bent-up gusset plates. Thus, the 60° angle section as a leg member provides better structural performance than towers with a conventional 90° angle section as a leg member with bent-up gusset plates. | |
