2023-05-29 16:00:09
For Philippe Leblond, research and engineering manager for construction safety at the Scientific and Technical Building Center, the collapse of a building is generally due to a lack of maintenance, even if, he notes, a building, in absolute terms, does not have a limited lifespan.
Are the collapses explained by the age of the buildings?
These collapses concern buildings of very varied ages and there are millennial wooden buildings in Japan that hold up very well. A building is built according to the rules of the art, which depend on its period of construction. In the 19the century, there were few national construction rules, they were rather local, even each craftsman had his own. The closer we get to the modern period, the more standardized rules there are about the right way to build.
According to current standards, a building is constructed so that, during an operating period of fifty years, the structure does not require major maintenance. Of course, buildings last much longer, especially if they are well maintained. The generation of buildings of the 1970s is, in theory, at the end of their initial operating life, many will require little maintenance thereafter to continue living their life without problems. Others will require work, more or less heavy, to extend their operating life.
On the buildings of the XVIIe century, even if the craftsmen worked very well at the time, the stage of significant maintenance has long since passed. There is therefore no limit to the lifespan of a building in absolute terms. But the lack of maintenance can cause the resistance limit to be exceeded, resulting in structural disorders.
What are the most common causes of collapses?
There are works undertaken too quickly, the drilling of load-bearing walls, which fortunately generally do not lead directly to a collapse, but to cracks. In Paris, we also see a lot of removal of masonry partitions, which were quite common in the 19th century.e and at the beginning of the XXe century. Originally, they were not designed to carry loads, but the building has deformed during its one hundred or one hundred and fifty years of existence, and it has leaned on the partition. Sometimes when you pull it out, you cause a little structural mess. But no collapse.
If we put aside the “anthropogenic” risks, linked to human activity (quarries, mines, fires, gas explosions), the cause which is almost systematically at the origin of a collapse is is the dilapidated state, the lack of maintenance. It is quite rare that it intervenes suddenly, in general you will see disorders worsen for ten, fifteen or twenty years and after many signals, the building ends up falling. Most of the time, water infiltration is the cause, even if it is not the source of the problem.
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