Last night, a partial collapse affected some parts of the structures belonging to the so-called Sky Sailone of the notes residential structures of Scampiaa symbol – for better or for worse – of the northern district of the city of Naples. The collapse, which occurred around 23rd Monday July 22ndinvolved several floors in elevations and caused 2 deaths, 13 injured and 800 displaced people, 500 of whom were unable to return to their apartments for the night. The images of the accident show that the structural elements of the building were in a state of decay: the Vela Celeste was in fact waiting for redevelopment interventions. Although the dynamics of the collapse and the reasons that led to the specific triggering of this structural fragility are not yet entirely clear, we can describe the salient points of the accident from a technical point of view starting from the architectural and structural conformation of the building.
The possible dynamics of the collapse at Vela Celeste from the reconstructions
According to the images circulating online, the area affected by the collapse appears to be confined to some of the connecting ramps between the central balcony and the main lateral structures. The connecting ramps from which the collapse started are those on the third floor, which is why they – in the fall due to gravity – involved the structures on the lower floors, namely the second and first, in a cascade, amplifying the damage. According to the reconstructions and statements of people nearby at the time of the collapse, the crisis that occurred seems to have been sufficiently sudden and without eloquent warning signs. For this reason, it seems natural to consider a possible fragile collapse in the areas where the landing connects to the main lateral structures or to the central landing. The landing, losing a support, has no residual load-bearing capacity and must necessarily collapse vertically. However, its collapse does not affect the main load-bearing structure and does not cause widespread propagation of the damage, as it is a secondary structural element to the statics of the entire building and the central landing.
The actual state of the load-bearing structures at the time of the collapse
They are currently being carried out by specialized technicians in-depth investigations to test the current level of structural safety of the work and there is still no official information regarding the outcome of these technical assessments. In fact, they require a minimum operating time necessary for the study of the current conditions of the building and the preparatory mechanical characterization of the construction materials, through specific on-site tests.
However, from the images that can be consulted it is clear that widespread state of degradation of the main structural elementseven in the area affected by the collapse. The presence of more or less widespread conditions of degradation is, predominantly, a symptom of a poor ordinary and extraordinary maintenance carried out on the building. This, unfortunately, is a recurring problem in the construction industry – public and private – that surrounds us. However, it is also true that to date there is still no certain information about the actual extent and severity of this condition of degradation and its role in news events, which is why it is not possible to draw objective conclusions today regarding the accident that occurred. The ongoing investigations will officially shed light on the actual causes of the collapse.
Engineering and architecture of the Vele di Scampia
Designed and built between 1962 and 1975 on an area of approximately 115 hectares, the so-called “Vele” are a complex of buildings serving public residential housing, built in reinforced concrete and with an architectural and structural conformation that geometrically recalls that of a sailfrom which they take their name. The thought architectural behind the Sails is that of maximizing the use of common spacesaimed at integrating the community into the central areas of the buildings, with a consequent minimization of the housing unit of the generic family nucleus. A concept that is also partly recalled in the futuristic project in the desert of Saudi Arabia.
The residential complex in its entirety consisted of several sails, 4 in this case in the lot of interest but 7 in total on the area of the 115 hectares mentioned above. These have been historically identified by colors: green, light blue, yellow and red. Some of these have been demolished in the past, following the approval of urban redevelopment projects. The light blue sail, the subject of current news, was awaiting redevelopment work on the basis of an existing project of several million euros. The same, therefore, it was not in the structural demolition program until today.
The structural conformation of the single sail leads to a distinction two important buildings with a plant decreasing in height, connected by a intricate network of internal galleries and walkways, distributed over various heights. The central gallery, which extends along the entire length of the sail in plan, is punctually connected by steel structures to the lateral bodies in reinforced concrete, while some flights of stairs and connecting walkways ensure the use between the floors and along the length of the sail.
