During the 19 September 2017 earthquake, steel buildings in the States of Morelos, Puebla, Mexico, and Mexico City were subjected to severe ground shaking. Despite in some cases, moderate damages in non‐structural elements were developed; generally, null or minor structural damage was reported. The notable exceptions are (1) a three‐stories building located at the southern area of Mexico City and (2) some schools near to the epicentral region in the State of Morelos. The behavior of these buildings is analyzed in detail. Conclusions are drawn on the demands imposed on steel structures considering the actual demands in order to underline the relevance of the normative design procedures.

In this paper, nonlinear static pushover analyses were carried out to assess the capacity and collapse mechanism of two existing transmission towers under wind loading. Different load distribution patterns were adopted from the application of the codified design wind load of the following countries: Mexico, United States, India, Japan and the New Zealand – Australian Code. Three-dimensional inelastic response analyses were performed using open access software. Analyses were employed to define the capacity curves, stress-strain curves for structural elements, the yielding mapping sequences and the collapse mechanisms, and to evaluate the influence of the tower body deformation and to assess the theoretical overstrength and ductility capacities. Results show a damage concentration, which leads to a fragile collapse mechanism with important strength reserves and a non-uniform distribution of yielding within the tower height. Since the collapse mechanism is not compatible with the desired performance inherent to the design philosophy, recommendations for the design stage are proposed, which pretend to ensure that the inelastic behaviour be consistent with the goals implicit in a code-based design to prevent tower collapses.

Hurricane Wilma hit Yucatan Peninsula in 2005, causing substantial damage to local electrical transmission towers. Based on the failure characteristics observed on such towers, an analytical study is performed to reproduce such failures and assess their vulnerability. Two latticed transmission towers are analysed under the action of 14 different wind velocity patterns corresponding to several national and international wind design codes. Displacement-controlled pushover analyses are performed to reproduce impending failure mechanism for considered wind patterns, and associated gradient wind speed is computed. Results illustrate that consistent cyclonic wind speed patterns lead to better estimates of failure mechanism and gradient wind values than traditional non-cyclonic patterns.

In this research, the response of high voltage transmission towers under wind load patterns is discussed from the point of view of structural reliability. The paper focuses the attention on the response of two existing tension towers that are part of the 400 kV circuit at the perimeter of Mexico City. Two hundred nonlinear pushover analyses were carried out in detailed models in order to study peak demands in the critical structural elements in tension, compression and in the critical support to establish the vulnerability as a function of the: i) variability of the lateral load pattern and ii) the material overstrength from commercial profiles available in the local market. Based on the results, the global buckling of the elements in the mid-height led to a fragile collapse mechanism, regardless of the applied loading profile. This observation represents a research opportunity in the design practice for the existing towers. The study identifies a dependency between the collapse mechanism and the structure height, which is not currently considered by the specialized codes.