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.
101 Présentation du cours
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来自 École Polytechnique Fédérale de Lausanne 的课程
L'art des structures 1 : Câbles et arcs
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从本节课中
Introduction
Cette première semaine vous permettra de faire connaissance avec l'environnement du cours sur la plateforme i-structures ainsi de vous rappeler les principes de ce que sont les forces.
Le sous-système est un élément décisif que nous utiliserons dans toute la suite du cours. Apprenez donc bien à l'utiliser pour résoudre les problèmes qui vous sont proposés.
Prenez le temps de bien comprendre la terminologie que nous utilisons, faites les constructions graphiques en vous assurant que vous pouvez bien imprimer les feuilles et apprenez à utiliser l'applet i-cremona.
与讲师见面
Olivier L. BurdetDr
Laboratoire de Construction en Béton
Aurelio Muttoni
Hello and welcome to the structures course.
Together, over the next weeks,
we will discover a series of properties of structures.
In this video, we will see what a structure is and what are the reasons
why we now have the professional profiles
of the engineer and the architect in our professions.
We will see what the "Path of Structures" is,
what are the contents of the course, we will see
what course supports are available, what are the prerequisites and
the required equipment. Finally, we will see how the course will be graded.
What is a structure ?
Nowadays, if one opens a dictionary,
we find that the part related to structures is not small.
But the part that is of interest to us it quite short, though:
"Conceptual design or study of structures, layout and calculation
of the structure of constructions". This still does not tell us
quite what a structure is, but it is in accordance
with what we will try to do in this course.
Where is the structure ?
Everything has a shape,
and quite often the shape hides the structure.
Indeed, the Statue of Liberty, which was
a gift of France to the United States for their
centennial is a structure, which withstands since more
than 100 years to wind, and it is quite exposed
on the Atlantic shore, so there must be
a structure, and in fact, as can be seen
in the schematic, it is a serious structure which
was prepared in Paris, France by the design office of Gustave Eiffel,
yes, the same who also built the Eiffel Tower.
We see here elements of the Statue
of Liberty which were pre-assembled in Paris,
to make sure that they would fit when they
would eventually be assembled in New York City after they crossed the Atlantic.
What we call a structure is the sum of all elements
constitutive of the assembly, the framework of a construction,
the skeleton if you prefer.
To be even more accurate, we will talk about a load-carrying structure.
Engineer and architect, you have no doubt already heard
from these two functions in the field of construction.
As a matter of fact, the two roles have not always been separate,
if we consider these two constructions from the Roman times, which
are about 2000 years old each, the "Pont du Gard" and the
Pantheon, well they did not have an architect or an engineer
to speak of properly, there were builders or master builders at that
time. It is later, approximately in the nineteenth
century that the separation
has occurred, which was logical insofar that the number of disciplines
to master was exploding, because there were new construction materials,
it was the beginning of steel, concrete
was soon going to appear, there were calculation
methods for constructions which were becoming
increasingly more accurate, but also more complex.
On the other side, and for buildings in particular,
a lot of new tasks were added, as
for example, a little later, the arrival of
lifts, of running water, and so on
which require that the architects have enough
time to devote to particular tasks.
Then both professional figures of the engineer and the architect, are
now separated and are separated for good reasons, but however they
cooperate in the field of structures, since the structures are a point
to be developed jointly by the architects and the engineers.
The aim of this course is
to enable you to understand the structures' behavior,
in order to know how to analyze them and to understand what happens
inside, but above all, to be able to
design them, to imagine new structures.
The organization of the course follows the one of the book "The art of structures",
I will come back to this book later,
which is called "The path of the structures".
This path begins on the left and finishes
on the right, with a progression following this arrow.
In the course "The art of structures I", which you are going
to take, we will stop over here, which means
that the schedule we are going to follow is
shorter, but he still have this arrow which is important.
This course must be followed from the left to the right consecutively.
It is not
possible to take it from the middle. Even if you have
prior knowledge, it will be difficult.
It is very important to walk through the early stages of learning
in order to be able to understand, consecutively, what will happen.
Indeed, it is very important to walk through all these stages.
If we look at this little boy who is putting a piece on the top of this
tower, we can say "well done, be careful", but actually, where
it was necessary to be careful, it is here, these pieces over here,
on the lower part, which carry all the rest of the tower.
If they had been incorrectly placed, there wouldn't have been
any chances to put a piece on the top of the tower.
Likewise, it is important to pay close attention
to the first lectures of this structures course.
They will maybe seem to you too simple, or maybe
even simplistic, but it is important
to understand them well to get strong bases which will enable you to progress thereafter.
And everything you will learn,
you will see, will be reused further, then if
you don't learn it well, you will have trouble following the course.
The course supports : they are very varied.
Of course the first support you will refer to
is Coursera itself, on which you will find
the videos like the one you are now watching, together with
quiz games and exercises. You will be able to refer to the website
i-structures : i dash structures, dot
epfl dot ch, which contains similar
information than in the videos, but in the form of lessons,
in a more classic form, that is to say composed of texts and figures.
You will have at your disposal on Coursera, course handouts (supports de cours),
in pdf format, which I ask you to print
every week and to have in front of you when you will watch the videos.
The principle of these course handouts,
and that is the way I taught this
course for many years, is to give you
incomplete course supports which you will complete
as the videos will progress.
Then, when you will see me writing something, generally,
you will have to write it on your lecture's notes.
This method will enable you
to acquire well the definitions I will introduce,
and also and above to make by yourself the graphic constructions
I will make and it is important
to make them by yourself in order to understand them well
and to master them, before starting the exercises.
Finally, you have the book "The art of structures" written by
professor Aurelio Muttoni, which is available in French,
English and in Italian, from the publisher EPFL Press, also known as
PPUR ; you will find
a link in the course handouts.
What are the prerequisites for this course ?
They are not that many because actually
it is a first year college course,
but it is a course which does not have a high level of requirements
in mathematics or in any other subjects.
Then what is important is that you are comfortable with
mathematics, you will be asked
to add, to subtract, to multiply,
and to divide, barely more; that you are also
comfortable with the idea of drawing with a ruler and
a pencil on a sheet of paper, because
these are operations that you will perform very often.
But this level is not very high, neither
in mathematics, neither in basic training.
Thus, I think that this course is open to almost
anyone who is ready to make the effort to follow it.
On the other hand,
you will need a computer. Well, I imagine that
if you are watching this video, you have access to
a computer, but it is important to say that
it will be necessary that it is a real computer, in quotes.
You will be able to watch the videos and to make a part of the
exercises, on a simple computer, like a tablet,
or even a cellphone, but, for
some parts of the exercises, particularly to use the JAVA applets,
you will need to have access to a computer, like a Mac,
a PC, or a Linux workstation, which can use all the
capacities of computers. In regard to the equipment, you see that the
equipment I propose you to use is very simple. Namely: paper,
rather than a pad, I suggest you to buy,
or to use a notebook.
The interest of a notebook is that it keeps a consecutive order,
so each week, you write Week 1, lecture 1, then
you take notes according to what you
see, maybe in the videos, but in particular in the exercises.
And then, a couple of weeks later, you will say to yourself "but,
I have seen that before" and you will be able to go back.
This is the advantage of a notebook, unless you
snatch pages, it will keep a memory of, not only what
you wrote, but also of the order in which you progressed.
Then, you will need a set square.
I propose you to try to find one with a
similar design than this one with additional lines, not only parallel to the long
side, but also perpendicular to it, because it enables to
make graphic constructions in a quicker and more comfortable way.
This set square should be at least
fifteen centimeters long, so you can
work comfortably.
You will also need a ruler, about 30 centimeters long.
A calculator will also be useful, but a very simple one with only four operations is enough.
You will soon discover that red and blue colors are very
important in this course, soI suggest you to buy either a
red pencil and a blue pencil, or one of these accountants' pencils,
like the one I have here, which combines the blue and the red.
And then, a pencil and an eraser will obviously be useful.
You will have eight exercises to perform. The exercises will be located on the website
i-structures, which will enable an automatic correction,
but you will access them from Coursera.
I have to say that these exercises, compared to other exercises that
you have maybe seen within the framework of Coursera or of another online course,
do not give you a feedback, or just a very little feedback
on your work. They will only
save your answers, and then, when the exercise
will be corrected, you will be able to see the correction,
but there is no intermediate indications,
save for a little colored indicator
which fades from black to deep green,
passing through red and yellow,
green being positive and red less positive.
This small indicator, even if it is not very accurate,
will inform you a little bit about where you are.
These exercises have to be submitted respecting the due dates which
will be indicated. A very accurate correction will
be made, and you will get, I don't know, forty-eight marks
from sixty-five for the exercise, and then, this score will be transformed into a
grade between zero, the worst grade, and three, the best one.
Then, at the end of the semester, the arithmetic mean of all
exercises will be done and everyone who reaches a grade of two on average,
will obtain a certificate for this course, and everyone who will reaches
a two point five grade will obtain a certificate with distinction.
This concludes this first video of the course
L'Art des Structures. Welcome and good luck !
I advise you to start watching
the next videos to start on the course material.
