How Do Arches Work? (with Demo!): Structures 2-1
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- Опубліковано 20 тра 2024
- We've covered cables...so now we're talking about how arches work. Arches are the opposite of cables. So, just as cables work in tension, arches work in compression.
A cable pulls in from its supports, so an arch pushes outwards. That's how they both span.
Now, you can see the force in a cable represented by the shape of a cable itself. But an arch is rigid so we can't "see" the force in it. What we can do is take the shape of a cable for certain loads and reverse it. That's the direction of compression force in an arch and we can call it a "thrustline".
A cable can fail in only one way: breaking. An arch can fail in two ways. It can fail equivalent to a cable i.e. a material crushing failure. Or, it can also buckle. In many ways, tension is stable while compression can be unstable.
We see this if we apply an off-center load to an arch. We place that off-center load on a cable, reverse its shape, and we see that the thrustline now leaves the material of the arch itself. The physical result of that is its easy to buckle the arch with the force applied off-center.
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Wow. I've just randomly come across this channel and the content in general is so interesting and really well explained. Thanks for your help and effort Paul
instead of using CGI or graphs, he explained it better with blocks of Mozzarella cheese.
Glad you both like the videos!
This is cool. Helped me understand the golf swing better. Straight line tension and arch tension in a rotary motion.
since i learned buildind those arches from a young age i tought a few tricks . i had the idea of how they work but now i can have complete understanding . for example why we place a heavier bigger one at the top . also why some times we make them odds are heavier than the even ones and why we try to ,depending the situation and needs to possibly place smaller ones but much more many of them .
Thank you mr Kassabian .
Fantastic explanation
Hi Paul, thanks a lot for the videos! It could be nice if you made one where you show how to represent an optimal arch curve graphically, explaining along the way the equilibrium of forces in a triangle and force polygon...
I love the representation and explanation . so easy to understand. best video on arches ive seen
Wow, thank you!
practical explanation..effective
LOVE this!!
Man i love your videos!
i don’t know why but until the end when the arch pieces fell, i thought it was made of cheese
Love your Effort, and heartedly thanks, Sir!
Much appreciated!
Thanks for educating in a simpler way
You bet!
Brilliant explanation's.
Thank you sir
Such a good and helpful vid. Thanks man!
Thanks Tamar!
Awesomely explained
Thank you 🙂
thank you for this. Can you tell me how to draw the thrust line??
Could we say, when walking across and arch bridge, to wait for another person to begin on the opposite side and walk at their same speed and the force will be equal and lessen the risk of collapse ?
This explanation vedio helps me a lot to understand about the arch. Thank you so much.
You are welcome!
Great video Paul... it would be nice to see a video like this about mexican vaults (bovedas mexicanas)
I might not be any smarter than before, but definitely more aware. Thanks for the videos!
You’re welcome!
Very interesting. On a higher plane than my usual vacuous video viewing. …. Thanks.
Glad you enjoyed it!
The thrust line through the arch is an upside down catenary. The Roman circular arch is only an approximation. Provided the section is deep enough it usually works.
Paul, I love this! I need this Romanesque arch for teaching. Did you make this? Great job!
I got this from: ssoc.ca/products/roman-arch
Not cheap but good quality and it helped as I needed to get a model while also meeting work deadlines etc!
@@PaulKassabian Thank you so much!! I am going to get one now.
Thanks a Lot, You probably the only one that understands that you don't bombard somebody with crazy analysis formulas before a person gets the concepts first.
I,m not a structural engineer: can you help solve my problem please ?.
i looked for explanations for a long time before i got to you. my problem is that im trying to understand how engineers determine the distances of webs in a Howe or king Truss, im tying to program Revit/dynamo software to create points on different distances on a span of length.
What is the formula u can use for determining how many webs you need say truss is 8meters how do you know the distance to divide the spacing for the in between webs ,the ones that are going down vertical ones the diagonals i can just join them i guess. how do you space them. This is for a common roofing of House. hip roof
The funny thing is easy to find the spacing between consecative trusses 600mm+- on internet but nothing on the webs spacing of a truss. the solution should work not just for 8m but for any meters span. forgive my grammar tried to edit it so many times.
What would be the considerations for a dome on Mars, where the (Earth-like pressure) under the dome would be about 100x that of the ambient pressure? The dome would act more like the chain, I suppose. How does one calculate the mass needed to keep your dome from flying off? Would it help to make (triangular) panels with layers, with different pressure between? So, going gradually from 1 bar down to 0.6 bar, outwards, with holes in the sides of the panels, on each pressure level, connecting to the adjacent panels. Or does that make no sense? Asking for a friend 🙂
To really capture the sense of how arches are cables in reverse, consider the flying buttress: arches achieve a high level of vertical load bearing strength by exerting those forces laterally, so an arch can be strengthened by supporting ti from the side with buttresses. However, when used in the design of cathedrals, piling up a bunch of rocks around your arch makes it hard to construct stain glass windows that actually let the light in, so the flying buttress was conceived to extend the buttresses away from the body of the structure.
This ironically had the effect of making these temples look like giant stone tents with the buttresses resembling guy ropes, which is significant in the Christian religion because the ancient Israellites from the time of Moses housed the ark of the covenant within a temporary structure known as the tabernacle that would later act as the blueprint for the more permanent Temple of Solomon that was to be constructed in the promised land.
may I ask more of .. (?)
Hi, Paul, I guess your explanation for the arch to stand is because the wedge blocks could push each other and the compression could transfer to the ground. Do I understand it correctly?
Yup! and the ground pushes back...equal and opposite forces...
So how did ancient architect's arches last for thousands of years? What did they do to prevent arch buckling?
The water of sea is salty how engineers protect rebars of pillars from rusting
How to overcome this issue.
Like, subscribe, turn on post notifications AND share! Thank you for another one Paul!
You’re welcome!
İs there any formula for calculate this model
What you say is right for a free standing stone arch on its own, but any stone masonry style arch will be buttressed to lock it all in to be effective and meet the structural integrity for purpose , I am no engineer
Make one with round shapes.
cool, reminds me school.
Sr please can i have a way to contact you
How much it gets for this work? Are there any jobless arches today in the World and is there any social security for unemployment of arches.
eat the cheese