PSI - Issue 62

Alberto Contardi et al. / Procedia Structural Integrity 62 (2024) 81–88 Contardi A., La Fortezza F./ Structural Integrity Procedia 00 (2019) 000–000

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12.22 billion of euros § . After Polcevera tragedy, when 43 people lost their lives, the same concessions were sold for 9.31 billion ** , so the loss of value of the company could be assessed in 2.9 billion. However, it seems that the same phenomenon has not occurred at all in the other events, where the number of casualties was a maximum of 2. So, what we could learn is that the amount of the psychological effect is a function of the probable number of victims and of the reason of the collapse. If the number of victims is very small (3 or 4 at most) or the reason for the collapse appears to be inevitable, the public opinion may perceive the event as a tragic accident . If, on the other hand, the number of deaths is higher, the event will be perceived as a disaster . A lot depends on how the event is handled and communicated, but just to give a magnitude of this problem, here the following formula of the costs in millions of euros is proposed (for collapse due not to natural events), where N is the number of casualties.  =3.523  −1  =1800−3 5  5 (3)

Fig. 1. Psychological effects cost function

4. Case study

To demonstrate the possibility of using this method, we considered a very simple case study, a hypothetical highway CC3 bridge of one span of 30-meter length that overpasses just a country road. This kind of structures usually has not seismic issues nor can it have hydrogeological problems, so the only limit state considered is the failure of the deck caused by the crack of a beam. We assume to know all the characteristics of the test bridge. As the vast majority in Italy, this bridge is made of reinforced concrete and has been built between 1960 and 1970, so the main structural parts are 60 years old. We also consider that the adopted steel bars of the original project were barely enough to meet the standard of the time. With this assumption, the starting safety factor of the bridge (without any deterioration) is  = ⁄ = 0.84 , using for  the actions requested by actual standards (Eurocodes). If we calculate the collapse probability in the next 50 years (using the method explained in a PIARC publication †† ), we will obtain 1.7 ∙ 10  ( =2.9 ). We suppose that the progress of degradation, due to carbonation and chloride attack, begins today and goes on through the next 30 years, so, in this hypothetical analysis, without interventions the final SF will be 0.61.

§ Autostrade per l’Italia, Relazione finanziaria annuale 2018, pag. 112 §§ Galvagni L., Atlantia: chiusa l’epoca Autostrade, venduta a Cassa per 8,1 miliardi - Il Sole 24 Ore - Finanza e Mercati (06/05/22) †† PIARC ITALY National Committee – Technical Committee 4.2 – Bridges – 2019-2023 cycle, Bridge safety monitoring and classification – State of the art and operational recommendations – Annex B.2