January 20, 2021

Buildings that endure a terrorist attack | Science

Buildings that endure a terrorist attack | Science

The call was already attracting attention: Buildings that are proof against terrorist attacks, explosions and natural disasters. And he added: "The first full-scale test-tube building has been built" which will be the object of a simulated attack in order to show its security. Once there, in a polygon of Alberic, 40 kilometers from Valencia, a powerful heavy machine is tied to a metal articulated column of one of the corners of a two-story building, unfinished, but loaded with 35 tons. Go back and stretch until the column yields and bends, but the building does not collapse. Despite the fact that one of its pillars has been broken, the structure of the building holds out, it is noticeable. Numerous mobile cameras collect the sequence. The professor of Engineering José Miguel Adam, director of the research team of the Polytechnic university of Valencia, command to repeat the attack with the same result.

The claim of the investigation, which has been presented this Thursday, is to reduce vulnerability of critical buildings, such as hospitals, schools, passenger terminals or institutional buildings of many plants; and avoid the total collapse that can be produced by a terrorist attack with explosives, by a truck that is thrown against one of the pillars or by a natural disaster like an earthquake.

According to Adam, with this new design designed for the corner columns, the impact on the Oklahoma building of the terrorist attack of 1995, which caused 168 deaths, or on the headquarters of AMIA (Asociación Mutual Israelita Argentina) in Buenos Aires, would have been reduced. Aires, who suffered a car bomb attack that killed 85 deaths a year later.

"It's about defining design techniques that allow the creation of alternative load paths, so that when a column fails, its load is redistributed among other elements of the building." In short, the buildings have resistant mechanisms that do not activate in situations normal, but that can have a great importance when it comes to enduring an extreme event, it is in the possible activation of these mechanisms where the improvement of the resistance to collapse of the buildings is focused ", detailed Adam.

The secret of the method lies in the placement and use of concrete during the construction process, in introducing changes in the conventional building method. And what are those changes, those design recommendations? The professor smiles and notes that the project's patent is being finalized by the University that has developed the research, which also has the support of a Leonardo Scholarship from the BBVA Foundation. He points out that the added cost of incorporating these design recommendations into the works would be 5% or less, in many cases.

Since the terrorist attack on the twin towers of 2001, much research has been done on construction methods to avoid collapses, the vast majority of times in laboratories or buildings just before being demolished. Therefore, Adam and his team insist on the importance of the construction of this test-tube building and the tests carried out on it, which have been co-financed by the Levantina, Ingeniería y Construcción (LIC) company.

Monotorized construction

The test-tube building has been monitored "with a series of state-of-the-art sensors, specifically strain gauges, sensors that monitor the deformation within the concrete, and displacement sensors and accelerometers, both electric and fiber optic. Different cameras, both conventional and high-speed, have been used to evaluate and visualize the response of the building ".

In addition to the two initial tests, in which the building has moved 48 millimeters, a third is practiced on another column of the opposite corner, with the difference that the top floor is partitioned, with walls. The building suffers even less, with a movement of 3.5 millimeters, which demonstrates the effectiveness of well-designed enclosures, says Adam.

The research, which has the support of the Ministry of Development, is part of the challenge Secure Societies of Horizon 2020 and aims to contribute to the achievement of the objective of "protecting and improving the resilience of critical infrastructures, supply chains and modes of transport". "With the development of this project, it will be possible to reduce the vulnerability of critical buildings (hospitals, schools, passenger terminals, public and military buildings), of high occupancy or with a high number of plants", concludes the director of the investigation.


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