On the night of today Monday 30 June 2025 thesign “Generals” that stands at the top of the Hadid tower (also called “Torre Generali” or “Palazzo Generali”) in the CityLife area in Milan, among the highest skyscrapers in Italy with 44 floors and 192 meters high that acts to the Insurance Company, about 2000 people work every day. Fortunately, given the time, there was no damage to people or things. The surrounding square was evacuated, the passage to pedestrians was banned and the exit of the underlying Tre Torri metro station was closed. The firefighters intervened on the spot (called around 6:30 in the morning) and the police forces to cordon and secure the perimeter around the building. The collapse consisted in the detachment of the tear from the steel reticular support structure that supported it. The sign, and part of the support structure in solidarity to this, are now partially supported by the terminal parapet of the building, in a provisional condition that requires external safety interventions.
What can this sudden collapse have to be? We do not know with certainty what the causes that led to the detachment of the tear from its support are, however it is possible to do some technical considerations on the possible trigger for collapse and on those who are – in general – The project problems of advertising elements at high altitude like the one in question.
What can be the causes of the collapse of the “General” mirror from the Hadid tower to Citylife
A possible explanation of the collapse can be summarized through two macro-thematic, although the actual cause of the collapse is most likely a combination of the two conditions and other factors that-at this moment-we do not know:
- Climatic conditions have occurred such to generate Vento actions greater than those used for the project;
- damaged damage induced by Fatigue phenomena on the metal structures and on the connections between the support rods.
Wind actions are not static, like the force of gravity, but they are dynamic actions With cyclic behavior. When dealing with structures subject to actions of this type, and even more so when the structural system is composed of metal elements, The fatigue phenomena represent the greatest design insidia: these act silently over time and are the cause of the propagation of cricche which, in extreme cases, can lead to collapse.
Therefore, excluding any design errors or the lack of controls and ordinary and extraordinary maintenance activities for the support structures of the tear, it seems likely that the collapse has revealed itself to achieve the effort of the support elements, probably induced by the continuous vibrations generated by the cyclical actions of the wind.
What are the forces that act on a sign like the one collapsed on the skyscraper in Milan
The advertising signs, especially its supports and anchors on the ground or to support structures at altitude (as in this case the cover floor of the tower), are substantially designed by guaranteeing – with appropriate safety margins – that the actions produced by the impact of the wind on these large surfaces may be download to the support structures. The wind is worrying for two main reasons:
- The impactful surfaces are relatively highso that the wind actions – due to the effect of pressure and depressions – they translate into important urgent forces that literally they push these signs horizontally and generate important vibrations of the same;
- there share Compared to the campaign plan on which the positioning of the tear takes place, it can be high enough to generate important Encourage increases.
As the height is growing at which an object is placed from the ground, the action that this itself suffers from the wind is growing significantly, for the same one of what is said Reference kinetic pressure, which instead depends only on the geographical area of reference. In essence, if we have, at the same point, two equal objects but placed on two different altitudes, The highest altitude will suffer the effects of the wind more.
References
DM 17 01 2018 – Update of technical standards for construction