Difference between external force and interface forces of remote loads

Simulation
1

Hi all

Here's my problem:

I have a wooden beam that supports an extension. this beam is 3.5 m out on the left side of my model where a force of 150,000 N (purple arrow) is applied at a distance.

Underneath, I have a 270 Y-shaped IPe post which is in support and which takes up 1 m of the 3.5 m of the wooden beam.

Behind it there are 2 steel supports in 15 mm thickness which are fixed to a concrete wall with M20 metal studs.

The wooden beam retracts 3 m on the steel support side.

The wooden beam is crossed by 6 threaded M16 rods which are screwed through the steel supports on the right,

I'm doing the simulation, from this point no worries at the level of the post, and my anchor bolts, but I would like to know if my 16 mm threaded rods hold the load.

So I look at the level of forces, and there is a problem, I don't know if I should look at the results at the level of external forces or interface forces of remote loading, because the results are not at all the same.

Does anyone have an explanation for the different results that soliworks gives me?

I attach in pdf the two results obtained by solidworks.

Thank you for your help.

2

Oops, I forgot to get the results


forces_externes__et__forces_a_distance.pdf
3

Hello@syltab

Before answering your question, we should bring to our attention the way you set up the simulation and why you did it this way.

Indeed, depending on your parameters, the resulting forces A, B or C make sense or not. Let's say that the resistances make sense in the case of lever force such as a torque wrench or lifting a load by lever, etc....

Because when I read this "no worries about the post, and my anchor bolts, but I would like to know if my 16 mm threaded rods hold the load."
I already present a possible error of reasoning because already putting threaded rods or anchor bolts by expansion or chemical is not the same thing at all.
In addition, it doesn't make sense to say that  the rods hold the load because they are not the ones who take up the load in the strict sense. But hey!

In addition, to obtain external strength, a virtual repository must be created.

For remote loading, you should already know if you have used remote loads on your beam or if you have used a distributed load or something else. Otherwise it would be futile to look for interface forces.

I will explain these preliminary remarks later after seeing the ASM.
You should post your assembly so that we can see your loads and especially the connectors used.

Can you indicate which version of SW you have
Can you post your ASM using the Pack and GO function and especially by attaching the result of your simulations.

Kind regards

4

Hello Zozo_mp,

Thank you for your answer,

I attach the file in SW2018, as well as the result file.

Since I asked the question, the loads have changed from 15 tons to 9 tons.

I modified the mod accordingly, but I'm still stuck on my results.

To explain it:

The extension is made of wood and there was a vertical post at the end of the extension. The end customer does not want this pole because he no longer has access to the garage with the car. I am asked for a steel post at an angle on a concrete footing about 1 m long.

This extension rests on a laminated timber beam 1 m high by 140 mm wide, which extends 3.6 m from the outside, rests on 3 m concrete slabs on the inside side. The carpenter put 6 threaded rods with bolts of 16 through this beam on the inside side and slabs,  (where I have to put the 2 steel supports), and props on the outside.

I have to check that its cl 8.8 threaded rods hold up thanks to my column (which, by its dimensions, I think, makes the beam rest almost in balance (but I may be mistaken).

I put a remote charge because I think or thought it was the right approach.

Anchor bolts are metal studs by expansions.

I hope I was as clear as possible, but ........

Thank you in any case for all the help received.


poteau_poutre_bois.zip
5

Good evening

Ok @Syltab

I had understood the essentials but your clarifications are precious!

I'll look at it tomorrow Friday and keep you informed.

Kind regards

6

Hello @Syltab

I have watched your simulation and you will find my comments in the attached PDF.

Here is  the image as I understood your assembly (I added the beam)

Kind regards


poteau_et_poutre_lamellee_collee.pdf
7

Hello Zozo_mp,

I have just read your comments and I thank you for it.

To clarify:

- As you have drawn, the wooden beam is good,  but between this beam and my small steel supports at the back there are concrete slabs, it is true that my supports are badly placed because it would have to be lower (of the value of the concrete slabs).

To answer your insightful remarks:

1 - The remote load that I have put is the value that the beam receives at its end (according to the carpenter, he counted permanent load, operation and accidental).

2 - On the two steel supports, where are the 6 threaded rods, I need to segment these surfaces by defining the support surfaces of the washers of 16 on the two steel supports? Have I understood correctly?

This can give me the resulting forces on the threaded rods that the load on the wooden beam induces ?

3- I don't know the complete assembly of the expansion, because everything is dressed and finished from the outside.

- The beam is on an edge of the wall, so the interior part rests on a wall made of a panel.

There is the same beam on the other side of the extension but with a wooden post; perpendicular and at the end of this binocular.

I will segment the surfaces of the steel supports by defining the contact area of the threaded rods.

If I simulate the surfaces of threaded rods on my supports and I look at the interface forces of the remote loads, with a reference for each rod, will I have a value that is not stupid?

I will redo the simulation and keep you posted.

I thank you again for the time you have given me, to help me move forward on this problem.

Regards

 

 

8

Hello, @Syltab

Thank you for your feedback

For point 2 you have understood well but look at the following comment before going any further.

For your case, I'm not a fan of remote loading as it is done because it doesn't take into account a possible deformation of the beam (especially the spill. I suggest you do a test like the image I attached to you with the beam in the simulation

You make an ASM with your share and you create another part wooden beam (choose pine as a material).
Then you choose "solidarity" between the different elements. You put the max load at the end of the beam and you compare it to your first simulation.

If your IPN part and the mechanically welded supports do not move more than in the first simulation, then only look at Von mises which will indicate the stresses + Displacement + Safety coeff.

From my point of view, and in view of my previous remark about bolts, no other forces should be sought than if the bolts work in tension, torsion or if the mechanically welded support was subject to a twist in order. In your case the bolts do, which is why they are designed without significant effort.

You will also see that the forces in your IPN mechanically welded will be different, in the direction less stressed or stressed differently (same for the two mechanically welded supports.

Kind regards