Hello
I am trying to determine the forces on this structure, it is an unstable system so not isostatic or hyperstatic
Thank you
capture2.png
capture2.png
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What software do you have?
Hello. Pl
it's for a sizing for a first time
I am looking to size the base which represents a beam of hollow square profile 100*100mm and thickness 5mm
Here
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Hello
Do you want to study the buckling of the lower beam? (The one between the 2 point supports)
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See this link by jean.lamaison
for the design of bending beams
Simply select the supports, profile, materials and different loads
and it gives the values live on the table
http://jean.lamaison.free.fr/flexion.html
@+ ;-))
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Re
I don't know the dimensions of the beam finally I want to calculate its length so I can't study the buckling
jean.lamaison's site I can't see that I don't have the reaction to the supports?
Thank you
It's a little more complex than that because the vertical beam is in compression, which emits a force on the horizontal beam.
Now, if the vertical beam compresses, it compresses both the oblique beams due to the connection at the top.
[Edit]: Indeed, there is also the reaction to the supports in addition
I agree but via the drawing posted I already see 2 long presses of X
then I have 2 sections in supports at 45 ° on the supports of the horizontal section and which rests on supports spaced X
to the mediatrix of these 2 sections at 45° a vertical section of log X
which rests on the axis of the horizontal profile
What is the purpose of the manipe
So look at this link which a free log
for the analysis of metal structures such as frameworks among others
http://www.freelem.com/guide/saisie.htm
The video
https://www.youtube.com/watch?feature=player_embedded&v=pOYWZt-WifA
with this maybe you will be helped
@+ ;-))
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Thank you gt22 for the software, but I need the dimension of the base beam ??
how does you want to calculate something if everything is abstract
you want to go on strangers
for now you have a charge and a section
You need a base of something, right?
your set is 10 cm 10 meters it's not the same weight the same lift
What will be the loads on your profile at 45°
That's why your story, what will it be for?
you're pretty confident in all your questions
@+ ;-))
GT22
Check this out
http://www.systemx.fr/meca/btsiut/treillis.pdf
yes I understood with feelem the guide I gave you in link you can do it without problem
For me I think the problem is solved via this log
it's up to you to look and specify the number of nodes
@+ ;-))
hold one of +
http://www4.ac-nancy-metz.fr/echanges-pedagogiques-btp/?q=node/253
and free ink
@+ ;-))
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Hello
I tried to redo a calculation of your system with the lattice method (Ritter's method indicated in your PDF) but, mathematically, there would be no effort in the vertical bar in the center of the triangle (I'm attaching my draft if you want to check).
This is obviously surprising, but it seems logical given the kinematics accepted to consider that the system is a lattice (pivot at all junctions). This method only allows normal forces to be calculated. However, this is not really the case.
Conclusion, we have to do with another method. In this kind of case, finite elements can be a good solution.
Otherwise, if you just want to size your horizontal beam, you consider that all the effort goes to the center and you're sure that it will hold. It's penalizing but it's fast and efficient (and for a load of 1 ton it shouldn't give a profile too big).
portique_treillis.pdf
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re
I saw your calculations, I did as you did, the calculation is right if we consider the structure as bars that work in tension-compression, but in my case I think I have a beam (base) worked in bending, so I did as you told me I considered the force passed in the center then I calculated the bending moment and II sizing I found L<=1.6m and I took 1.5m that's what there is in the builders' cities
Thank you for the calculation of the moments, it's nice