Structural dynamic and buckling behaviour of steel cold-formed polygonal conic pole for antennas support Eduardo de Miranda Batista 1 , João Alfredo de Lazzari 2 , Gustavo Yoshio Matsubara 1 , Michèle Pfeil 1 1 Introduction Expansion of the internet and cell phone signals need the installation of additional facilities, including support for antennas placed as high as 40-50 in both urban and rural areas. Traditional structural solutions are based on trussed or pole steel towers, the former with much larger base area than the later and the consequences for the costs of the ground occupancy. This aspect is of upmost importance and the reason for the development of higher steel poles with steel polygonal cross-section, searching for light solution based on cold-formed thin-walled structures. 1. COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. 2. CERIS, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal. The main results of the study for the improvement of 20-sided polygonal conic steel cold-formed pole are presented, including a 40m high antennas support. The study was developed based on the 30m high reference design pole illustrated in Figure 1, originally designed by BrasilSat Harald S/A company. For this, the cross- section was taken with 1450 and 300 diameter at the bottom and top, respectively, the steel plate thickness may be taken from 2.65 to 6.35. The pole is composed with 6m length elements, designed with slip joint or bolted flange connection. Furthermore, the study included the presence of maintenance openings along the pole, that must be reinforced to avoid premature localized collapse. Finally, groups of antennas were considered at: (i) level 35: 3x(1.95x0.4m), 3x(0.36x0.26m), 1x(φ0.6m); (ii) level 40: 12x(1.96x0.25m) and 12x(0.36x0.26m). Drag coefficients for the antennas are 1.2 for rectangular and 1.6 for circular shapes. 2 Wind-induced dynamic behavior and loading Pole towers may exhibit dynamic behavior induced by wind ORIGINAL ARTICLE Abstract Support for antennas placed as high as 40-50m demands traditional trussed steel or pole towers, the former with much larger base area than the later and the consequences for the costs of the ground occupancy. This aspect is of upmost importance for both urban and rural areas and the reason for the development of higher steel poles with polygonal cross-section, searching for slender thin-walled structures. The present research focus is cold-formed steel conic twenty- sided polygon solution allowing 40-50m high antenna support, for which one must deal with the following challenges: (i) wind-induced dynamic behavior, (ii) buckling analysis, (iii) localized stress concentration close to the openings along the pole, (iv) connection solution that strongly affects the erection procedure and (v) the fatigue effect. Beyond these aspects, results of the dynamic behavior, elastic buckling, nonlinear structural behavior until the collapse and design procedures for the computation of the structural strength of the steel pole are presented and commented, revealing the importance of structural analysis by combining tailored numerical tools as the finite strip and the finite element methods, as well as frequency domain methods for smooth and turbulent wind actions. Additional CFD and experimental wind tunnel results should be considered for advanced structural design, as well as experimental structural analysis to confirm the set of numerical results and the design procedures adopted for the steel polygonal poles. Keywords Antennas support system, Steel pole tower, Cold-formed steel structure, Wind-induced dynamic, Buckling analysis Correspondence Prof. Eduardo de Miranda Batista Civil Engineering Program COPPE, Federal University of Rio de Janeiro C.P. 68506 21945-909 Rio de Janeiro, RJ Brazil batista@coc.ufrj.br