Despite his almost 55 000 seatsdistributed between grandstands, curves and distinct at altitude on two levels, lo Maradona stadium He works – to date – preserving a historical limitation imposed on his maximum capacity, dictated by theimpossibility of opening to the public the famous third ring: we are talking about the summit of the stadium, now physically separated from the remainder by means of imposing barriers. Made on the occasion of the construction of the metal coverage, in the 90s, he had only a few moments of effective use in his life to date. But why was it closed? The system of beams that allows the creation of the new seats has a vibrational problem. Recently, it seems that particular analysis and preliminary investigations have started to better study the phenomenon and understand what the more effective solution to the problemtogether with other redevelopment interventions of the work as a whole.
The structural system of the Maradona stadium
To better understand the problem that afflicts the third ring we must understand the structural functioning of the stadium in its entirety. To guarantee Complete visibility From each point in height, the support structures for spectators must be built in such a way as to allow sufficient vision even in the highest areas of the stadium. In the case of Maradona, this takes place through two different structural systems:
- The underlying part of the stands, made up of first two rings of the same, is made in reinforced concrete And in fact the original structure of the previous one is San Paolo stadiuminaugurated in 1959 These costons reach up to the foundation and then download all the weight of the steps – and the loads on them agents – to the ground in depth.
- The upper part, which includes the third ring, is a more recent work (1990) and appears to be structurally disconnected from the previous one. This part is in turn composed of two large macrostructures:
- Cover horsesformed by gigantic stainless steel towers to which a huge thickening of about 30 meters long, which opens overwhelmed inside the stadium and acts as a support for internal coverage.
- The gray of beams between two consecutive towersforming the third ring from the point of view of the sessions. This gractio aimed to increase the capacity of the stadium, brought to about 76 800 seats in the few moments of opening following its construction.
Because the third ring is closed: the cause in the vibrations of the beams of beams
The structural problem that does not allow the opening of the third ring to the public is essentially associated with a excessive vibrational problem of the steel grill, that is, of the system of beams that allows the creation of the new seats. Basically, it means that The steel beams that make it up are very susceptible to the loads that act there and to the way they are applied: the loads, in this case, are nothing more than the spectators and the way they are applied are nothing else that the movements that these perform during the game. That is, it happens that, when the gracbio structure begins to load, it also begins to spread a annoying vibrational phenomenon which spreads throughout the system, up to the side supports (the towers) and – it seems – also to the surrounding buildings. These are the reasons why, shortly after its mass, it opted for its provisional closure.
What consequences can this phenomenon lead to? Mainly two. The first consequence is that the generic spectator who is in a point of the third ring will begin to undergo the effects of the vibrations, warning a strong sense of annoyance caused by the accelerations that the body undergoes: in itself, this already identifies a correct functioning of the structural system, although this does not compromise the static of the system.
The second immediate consequence of this weakness is linked to the possible Fulfure of resonance phenomena: If the trigger the vibrations persist, the breadth of the same can increase significantly, gradually generating more and more discomfort and possibly exposing metal structures even to fatigue problems that accumulate over time. The currently safer condition for the use of the stadium is therefore to eliminate the problem through theinterdiction to the public of the third ringso as to eliminate the trigger for vibrations in full and – consequently – any dynamic amplifications caused by it.
Possible decisive strategies
In the study of vibrational phenomena and of the reduction of the effects that dynamic loads cause on the structuresit is possible to act mainly by following three distinct roads:
- Variation of the rigidity of the systemor his ability to oppose elastically to external stresses. This can take place, for example, by connecting the gract to the reinforced concrete structures of the second ring, that is, by varying the support systems of the main beams.
- Variation of the system mass: a solution could be to design appropriate masses, so -called grantedcapable of contrasting the vibrations generated by loads. These masses would act through a system similar to that present within the Taipei 101, which is activated in the event of strong winds or earthquakes.
- Increase in structural dampingor the ability of the structure of dispel These vibrations through special devices, suitably sized and positioned. In this case, the solution would be much more similar to that introduced for the resolution of the famous oscillation problems of the Millennium Bridge.
Let’s make a simpler comparison: vibrations are like an annoying tickle on our body. The loads that act they know perfectly the point where we suffer more. Then we can say that in the first two cases of intervention it is as if I had found a way to move my weak point in some other part that no one knows. In the third case of intervention, however, the weak point remains there where it was before, but I try to cover it as much as I can so that it will give me as much annoyance possible.
