Conveyor 160' long 1

[mrMikee]

I just received a layout drawing of a 160' conveyor going from a hopper at the base to the top of a storage bin, and it is rigidly connected on both ends. When I worked with conveyor people years ago it was considered good practice to fix the conveyor at the base and provide a pinned link at the top. This link would be a short vertical support pinned on both the top and bottom to accept a small amount of movement. Otherwise with a rigid connection the conveyor will take the wind and seismic loads on the bin and thermal expansion forces from the conveyor.

Maybe this is no longer considered necessary? Does anyone have an opinion or comment?

BTW, it's still my opinion that the top connection should have some flexibility, but maybe this is a thing of the past.

Thanks,
-Mike

 

[SperlingPE]

Thermal expansion should be considered.
As far as wind and seismic, what kind of deflection can the conveyor stand?
What support is there for the conveyor to resist lateral forces?

 

[mrMikee]

SperlingPE,

This conveyor is supported at about 40' centers by the typical A-frame supports. These will provide good lateral support but are relatively flexible for longitudinal forces. As far as loads and deflectios of the conveyor I need to get more info from the vendor.

Thanks,
-Mike

 

[aggman]

Typically we design the support on the top of the bin as a pin - pin support (a roller) and fix it at the tail or at the drive tower if its not a head drive. We would then allow the reactive forces at the head to be absorbed in the truss chords to be resolved out at the fixed (pinned to lateral translation) support. Obviously you could design the bin to handle the drive forces if this is required. Temperature effects should be considered, but I would doubt they are controlling at your conveyor length.

I once had to support a 500 HP drive on the top of a rectangular surge bin, (about 60' up). The drive load was overloading the truss chords so I had to build in lateral trusses to transfer the drive load to the bin. The bin handled the loads just fine, but I ended up putting out-riggers on the support columns to transfer the shear to the concrete. It also can require a lot more concrete than typical due to overturning loads.

Back to your conveyor you could place a slotted connection (slot at the angle of the conveyor) to allow for lateral translation. Ideally this would be a double shear connection with an actual pin in it, not a bolt. This would free the conveyor to translate and still allow them to set it close to the top of the bin. If you don't allow it to move then you will have to deal with the loads induced onto the bin due to drive forces and temperature forces. (In my opinion)

 

[mrMikee]

aggman,

I haven't used slotted holes yet but consider it an idea to keep in the bag of tricks for when nothing else will work. It is however something that could work. The message I get from the rest of your post is that engineers will engineer something like this. In my opinion bins and conveyors are an engineered product and therefore should be engineered. That's not always the case.

Now for my next problem, how does a W6x20 column work for a 200 ton agg bin.

It's always something.

Thanks,
-Mike

 

[aggman]

Yeah I know what you mean. I can't tell you how many times I have heard, "But it worked before! I can't see how adding a measly 10 tons of capacity would require you to beef up the structure!" Never mind that you have to check things without safety factors just to be able to prove that it works now.
As far as my post is concerned I guess I was confusing. I guess I was trying to say the following. I agree that your ideal roller is the common and desired approach. I was also pointing out that in certain instances you can design for your fixed case and it has been done before if it was so required.