How Cables Work - With Diagrams! (Structures 1-2)
Summary
TLDRPaul Kasabian, un ingeniero estructural, ilustra cómo funcionan los cables mediante una demostración física con una cuerda y paquetes de arroz como peso. Expone cómo la posición del peso altera la tensión en la cuerda. Posteriormente, utiliza imágenes para demostrar visualmente cómo la tensión varía, utilizando rojo para representar la tensión y su profundidad para indicar su magnitud. Explica conceptos como la carga equilibrada, el aumento de tensión al separar pesos y cómo la tensión se distribuye en sistemas simétricos y asimétricos, concluyendo con una breve explicación de las puentes colgantes y la forma parábola de los cables.
Takeaways
- 😀 Paul Kasabian es un ingeniero estructural que explica cómo funcionan los cables mediante demostraciones físicas y diagramas.
- 📏 Se utilizó una cuerda y paquetes de arroz como peso para demostrar cómo la posición del peso afecta el movimiento del cable.
- 🔴 El color rojo representa la tensión en los diagramas, siendo más oscuro cuanto mayor es la tensión.
- 🎛 Cuando el peso está en la mitad del cable, la tensión se divide igualmente entre las manos que lo sostienen.
- 🔄 Al separar las manos, la tensión en la parte superior del cable aumenta, reflejando un rojo más oscuro.
- 🔄 Al mover el peso hacia un lado, la tensión aumenta en esa región, mostrando un rojo más oscuro en el diagrama.
- 🌉 Se menciona el Golden Gate Bridge como ejemplo de un puente de suspensión, donde los cables principales soportan el peso a través de horquillas verticales.
- 📐 La forma de un cable con carga equilibrada es parábolica, lo que se utiliza en la diseño de puentes de suspensión.
- 🏗️ Se muestra una imagen del puente de Manhattan en construcción para ilustrar el proceso de construcción de puentes y cómo se planifica la posición de los cables y la cubierta.
- 📚 La demostración fue cualitativa, enfocándose en entender cómo funcionan los cables en lugar de aplicar fórmulas cuantitativas.
Q & A
¿Qué profesión ejerce Paul Kasabian según el guion?
-Paul Kasabian es un ingeniero estructural.
¿Qué herramienta utilizó Paul Kasabian para demostrar cómo funcionan los cables?
-Utilizó un hilo físico y paquetes de arroz como peso para realizar una demostración física.
¿Cómo cambió el movimiento del cable cuando se le puso peso en diferentes partes?
-El cable tuvo que moverse para soportar la tensión en la dirección de la fuerza que lo atravesaba, y llevar esa fuerza de tensión de vuelta a los soportes.
¿Qué representa el color rojo en las imágenes que Paul Kasabian muestra?
-El color rojo representa la tensión en los cables, y cuanto más profundo sea el rojo, mayor será la tensión.
¿Qué sucede con la tensión en un cable vertical que sostiene un peso y es sujetado por una mano?
-La tensión es la misma todo el camino por el cable, ya que el peso es constante y está en equilibrio.
¿Cómo se ve afectada la tensión cuando se coloca el peso en el medio de un cable y se separan las manos que lo sostienen?
-La tensión se distribuye entre las dos manos, lo que hace que el color rojo se vuelva más claro, indicando una tensión menor en comparación con cuando el peso está en una sola mano.
¿Qué sucede con la tensión cuando se separan más las manos que sostienen el cable con un peso en el medio?
-La tensión aumenta, lo que se refleja en un color rojo más oscuro en la parte superior del cable, debido a que se está ejerciendo una mayor fuerza horizontal para separar las manos.
¿Por qué hay una mayor tensión en un cable cuando se mueve el peso hacia un lado?
-Cuando el peso se mueve hacia un lado, una de las manos asume más de la carga, similar a la situación inicial donde una mano sostiene todo el peso y la otra no hace nada.
¿Cómo afecta la adición de peso en un cable la tensión en diferentes partes del mismo?
-La adición de peso aumenta la tensión en la parte del cable donde se coloca el peso, debido a que hay una combinación de fuerzas verticales y horizontales que actúan sobre el sistema.
¿Qué relación hay entre la forma paráboloide de un cable y la carga uniformemente distribuida?
-Cuando hay una carga uniformemente distribuida horizontalmente a lo largo de un vano, la forma del cable asume una curva paráboloide, que es la forma natural que toma un cable para soportar cargas equilibradas.
¿Por qué se utiliza la forma paráboloide en el diseño de puentes de suspensión?
-La forma paráboloide es utilizada porque permite que los cables soporten cargas de manera eficiente y equilibrada, lo que es esencial en la construcción de puentes de suspensión.
¿Qué se puede aprender de las imágenes del puente de Manhattan en construcción?
-Se puede aprender sobre la secuencia y el proceso de construcción de un puente de suspensión, y cómo la posición final del cable y la cubierta pueden ser diferentes a lo que se ve durante la construcción.
Outlines
🔴 Funcionamiento de los cables y su tensión
Paul Kasabian, un ingeniero estructural, realiza una demostración física y visual de cómo funcionan los cables con una cuerda y paquetes de arroz como carga. Expone cómo la posición de la carga afecta la tensión y el movimiento del cable, utilizando el color rojo para representar la tensión y su intensidad. La demostración incluye variaciones como la separación de la carga y la adición de pesos adicionales, mostrando cómo la tensión cambia en respuesta a la fuerza horizontal aplicada.
🌉 Comprensión de los puentes de suspensión
Se hace una comparación entre la demostración de cables y los puentes de suspensión, como el Puente Golden Gate, donde los cables principales con cableros verticales sostienen la carga de la cubierta. Se explica cómo la forma paráboloide de los cables se debe a la carga igualmente espaciada y cómo la construcción de un puente implica una secuencia y planificación cuidadosos para adaptar la posición de los cableros y la cubierta. El vídeo utiliza imágenes históricas de la construcción del Puente de Manhattan para ilustrar el proceso.
Mindmap
Keywords
💡Ingeniero estructural
💡Cables
💡Tensión
💡Peso
💡Soporte
💡Suspensión
💡Horquilla
💡Parabola
💡Constucción
💡Cámara
Highlights
Paul Kasabian demonstrates how cables work using a physical string and rice packets as weights.
Different parts of the cable move due to the tension and force applied to it.
Tension in the cable is represented visually with the color red, with deeper shades indicating greater tension.
A vertical string carrying a weight shows equal tension throughout due to equilibrium.
When weight is placed in the middle of the string, tension distribution changes, causing the color red to lighten.
As the weight is pulled further apart, the tension in the cable increases, shown by a deeper red color.
The horizontal force applied to the cable affects the tension, especially noticeable when the weight is moved to one side.
Adding symmetric weights to the cable results in an equal horizontal force on both sides.
The tension in the cable increases where additional weight is added, even if the weight itself doesn't change.
Suspension bridges are compared to the demonstration, with main cables and vertical hangers supporting the bridge's deck.
The shape of a main cable in a suspension bridge is parabolic when under an equal load.
An old picture of the Manhattan Bridge during construction illustrates the step-by-step building process.
The final position of the bridge deck is lower than its initial construction state due to the sag of the main cable.
The importance of understanding the sequence of construction for bridges to ensure proper positioning of components.
Cables in structural engineering do not rely on formulas alone but require a qualitative understanding first.
The presentation concludes with a basic understanding of how cables work in structural applications.
Transcripts
hi i'm paul kasabian and i'm a
structural engineer
so we just did a physical demonstration
of how cables work by using
a physical string and some little
packets of rice as weight
so we could see how putting weights on
different parts of the cable
changed how the cable moved because it
had to it had no other choice
it had to move to carry the tension in
the direction of the force that was
going through it
and carrying that force in tension
back to the supports so what i'm going
to do now
is i'm going to show a set of images
this is going to be the first one
and through those we're going to do
exactly the same as the physical
demonstration but as diagrams
and what you'll see is every time there
is tension i'm using the color red
so today everything's going to be red
because it's cables
and that's all the cables could do and
the deeper the color red
the larger the tension will be in the
cable so sort of a visual way of
representing what we saw by
sort of twanging the string so here we
go there's a vertical
string it's carrying a weight and
there's a hand holding it
up the tension is the same all the way
up
the string all the way up the cable it
has to be because
the weight is the weight and the tension
is equal to the weight
it's all balanced all in equilibrium as
we say
now if we separate out just slightly by
say putting that weight in the middle of
some string and holding our two hands
apart just a bit
now if you've noticed we'll go back the
color of the red has just
just dipped slightly it's gone lighter
why because
half the weight of of this this weight
at the bottom is going up to one hand
and half to the other
right each hand's basically helping
carry half the weight
but as we'll see even though the weight
doesn't change as you try to pull
the cables further and further apart
this weight will start moving up
this little small bit is is equal to um
the red of the weight of the
of the this anvil at the end and um
as we're pulling further and further up
you'll see that's a very very deep red
at the top
and you probably know this intrinsically
right the more you want to pull
a weight a string with some weight in
the middle the the larger the tension is
you're pulling more
even though this weight hasn't changed
how heavy it
is right and so your horizontal
force is increased while the vertical
part that you're
carrying has not changed but the total
of the sort of resultant as we call it
of the horizontal force you're putting
in
and that same vertical that stays steady
as you move it up
and this is sort of slowly moved up is
going to
increase as this is the biggest tension
we're putting into
the cable and then you remember i sort
of moved it over to the side
and here you can see a darker red over
to this side than the other and that
should also make sense because
afterwards they keep moving it over to
this side
and i was directly under one hand that
would be like the very first image where
one hand is carrying all the weight and
the other one's really not doing
anything
and here we have the really sort of
interesting part where if it's all
symmetric
and we have two weights then the
horizontal amount that these
these hands are pulling to each side
that's exactly equal to the horizontal
force that's going through
this part of the cable because that is
horizontal but there is a
bigger tension going through
the two parts of the cable either side
it's really interesting this it's the
same
cable it can be continuous which it was
when i was doing the string with the
packets of rice
going all around but right here right at
that point where we've
added weight the tension increases
in this part of the cable and it has to
why because this weight all of this is
going up this cable and has some
vertical amount but there is also a
horizontal amount that is being applied
to the system
simply because one hand is to the right
and one hand is to the left
right there's that's how we span
distances
so and this being symmetric is exactly
the same on the other side and we can
keep adding weights to this
um this is sort of putting it now with
one in the middle again this part right
here
just this area the tension in these
would be i'm going to go back
exactly the same as when we had the same
geometry which is somewhere between
these two
before right so these systems work and
you can kind of add
to them as you go up highest tension
lower tension
and right here we've got some tension
more and even more
and we can keep adding weights to this
as we go and that was a very interesting
moment here which is it doesn't matter
where these weights are
in height whether they are here or
dropped down to that position
they're still just vertical weights and
the reason of course i've done this is
because
this may remind you more of what
suspension bridges look like
suspension bridges are exactly this a
big main cable
with vertical hangers holding
weight along along the deck of a bridge
and so this was the example we gave the
golden gate bridge sort of one of
the best known suspension bridges you
have the big main cable
going up to these towers in this case in
this case if i go back to here you see
how those
hands are going up into the side
what you've got is the up part is being
held by the towers but you
but the rest of the cable goes back
what's called the back standstill
to balance out that horizontal force
this is the drape
that a main cable takes the actual shape
is called a parabola
if you have an equal load spaced
horizontally
across a span then you as you put those
loads together
the shape of the cable becomes parabolic
so if you've done that in in when you do
study maths then
you the if you would why am i serving
parabolas well you use them in the
design of suspension bridges among other
things
and i love this this is an old picture
of the manhattan bridge during
construction i wanted to show this
because obviously we build
structures step by step and you'll see
as there's a real large sweep
to the bottom of the hangers at this
location
so as they're going to add the other
bits of deck
that top cable is going to sag down a
bit
and the final position of the deck will
be
lower than what you see right here we
never sort of build bridges be totally
flat a bit of a camber to them
drainage and everything but it will be
less than what you see here
so as they did this they had to think
through the sequence of those to know
where these were going to be
as they're going to add the different
bits of deck to it
so here we go that is cables as a basic
understanding all of this has been as
you've noticed qualitative
rather than quantitative because in this
to
in this aspect cables don't do formulas
like we do we apply arrows and numbers
to it to make sure we can quantify these
things but
the very important first step is to
understand
how cables work so this was the first
of our sort of primary colours of
[Music]
structure
5.0 / 5 (0 votes)