600 Les arcs

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From the course by École Polytechnique Fédérale de Lausanne

L'art des structures 1 : Câbles et arcs

23 ratings

École Polytechnique Fédérale de Lausanne

L'art des structures 1 : Câbles et arcs

23 ratings

L'art des structures propose une découverte du fonctionnement des structures porteuses, telles que les bâtiments, les toitures ou les ponts. Ce cours présente les principes du dimensionnement et les structures en câbles et en arcs. Un deuxième cours présente les structures en treillis, en poutres et en cadres. Après avoir suivi ce cours, vous serez capable d'identifier les structures en câble, en arc et en arc et câble. Vous pourrez déterminer les efforts dans les éléments de structure principaux et procéder au choix de leurs dimensions en fonction du matériau de construction choisi. Votre maîtrise des constructions de statique graphique ainsi que de l'applet de calcul i-Cremona vous permettra de comparer diverses solutions et de choisir la forme la plus appropriée pour un type de structure donné. De manière générale, vous pourrez, en observant les structures autour de vous, reconnaître leur mode de fonctionnement, expliquer le choix de leurs dimensions et de leurs proportions.

From the lesson

Arcs

Le deuxième type de structures que nous découvrons dans ce cours est celui des arcs. Ces structures ont un comportement assez différent de celui des câbles, mais nous verrons que la détermination de leurs efforts est très similaire, ce qui nous permettra d'avancer assez rapidement.

600 Les arcs2:25

610 Forme et stabilité des arcs18:16

630 Rigidification des arcs27:57

650 Articulations des arcs17:06

660 Poussée et ligne des pressions30:17

Meet the Instructors

Olivier L. Burdet
Dr
Laboratoire de Construction en Béton
Aurelio Muttoni

Hello.

We start today the lecture on the arches.

When we talk about this kind of structure, we often think about the vaults of Antiquity.

What you can see here, for example, they are

vaults of the Roman thermal baths which have been built around

twenty centuries ago, by builders who did not

know the principles of statics and who did not know,

of course, how to calculate the structures.

The purpose of this lecture today is precisely to learn these principles.

The experience of builders of Antiquity were particularly based on what

they have seen during the construction of the vaults, and

also during the collapsing of these structures, indeed there

were lots of them which collapsed in the past.

We have here a model which reproduces quite well a masonry vault.

We can see,

very well, for example, how such a vault can deform.

We can see here, for example, that we have the opening of

joints between the arch stones which compose the vault, and we can

see very well by where passes the pressure

line, that is to say the internal force inside the vault.

The study of the geometry of this pressure line is

fundamental to understand what is the ideal shape of a vault.

And that is what we are going to study, in this lecture.

That is from the moment when we have better

understood the functioning of this type of structure, that

we have developed graphical and analytical tools

which enable to determine the ideal shape of the vaults.

And it is from this moment that the architects and the engineers

have been able to design structures as for example the arch that you can see here,

it a structure of the 19th century, no longer only based on the experience,

but also on graphical and analytical methods.

It has also enabled to progress

towards much thinner structures like the reinforced

concrete shell that you can see here, it is only

a few centimeters thick, or this one, it is also a reinforced concrete

shell of ten centimeters thickness, which I have designed a few year ago.

The learning center, this structures that the students

of EPFL know very well, it is also an example

of reinforced concrete shell which works exactly with

the principles that we are going to study in this lecture.

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