Browsing by Author "Montenegro, P.A."
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- Impact of the train-track-bridge system characteristics in the runnability of high-speed trains against crosswinds - Part II: Riding comfortPublication . Montenegro, P.A.; Ribeiro, Diogo; Ortega, M.; Millanes, F.; Goicolea, J.M.; Zhai, W.; Calçada, R.Passenger riding comfort is a major concern in railways, particularly in high-speed (HS) networks due its strict requirements. Both the track and vehicle conditions may influence the comfort experienced by the passengers, but other external factors may also do it. Among these factors, the effects caused by crosswinds stand out due to the high levels of vibrations that may cause to the vehicle. However, almost no studies in this regard can be found in the literature, since most of the works do not consider external loads and do not analyse this phenomenon on bridges. Thus, the present work aims to fill this gap, by evaluating the passenger comfort on bridges subjected to crosswinds with different lateral structural behaviours and track conditions. Based on the vehicle's accelerations computed with an in-house dynamic train-track-bridge interaction tool, the Mean and Continuous comfort indexes defined by the European norm EN 12299, as well as the Sperling index, have been assessed for distinct scenarios. The bridge's lateral behaviour shows a negligible effect in the riding comfort, as well as the track quality since the wind load is much more determinant for the carbody vibrations than the track irregularities considered in this work.
- Wind-induced fatigue analysis of high-rise guyed lattice steel towersPublication . Ribeiro, Diogo; Bragança, C.; Montenegro, P.A.; Carvalho, H.; Costa, B.; Marques, F.Wind-induced fatigue is a major issue for the design of slender high-rise structures. However, there are still few studies focused on this topic, resulting in a lack of practical design procedures for this type of structures. This paper aims to fill this gap by presenting a complete and practical methodology for the wind-induced fatigue life assessment of high-rise towers and its application to a 120 m cable-stayed steel tower composed by a modular lattice. The wind actions were considered as the sum of the quasi-static component according to international codes and a numerically generated, trough an ergodic stochastic process, turbulent component which is based on the Kaimal wind spectrum. Real wind measurements were also taken for a period of 15 months on a nearby MET station which, when compared with the normative scenario, proved to be much less conservative and were not used for the safety analysis. The wind velocities were used as inputs for a nonlinear dynamic analysis from which stress time histories were derived for 10 potentially critical structural details. The damage in each detail was computed through the application of the Rainflow counting algorithm and Palmgren-Miner’s damage accumulation law, indicating the connection region between the modules as the critical detail with respect to fatigue damage.