aluminium support platform 1

[eski1]

hi
i have been asked to design a support platform which can be used in large dryer tanks . The platform has to be supported in the center only ( as all dryers have a hoist postioned above center to remove spray dryer) and it is on the hoist that this has to be supported. The platform needs to be able to do tanks ranging from 5 - 10 meters diameter and support 2 workers and small plant i.e welder ,grinders .It has to be easily assembled , lightweight and sturdy .I can see that to do the different tank sizes it would need to be either telescopic or have sections put on to gain more lenght , but i am really stuck as to how to make it stable and safe just supporting it in the center .
Any help on this project would be apprieciated

cheers chris

 

[pmkPE]

Have you considered truss type braces radiating out from a cylindrical center column?

 

[eski1]

I have looked at taking a central shaft down thru the centre of the platform and having wire rope diagonals going from this at the top and bottom to the edge of each side of the platform . I couldn't see how this would stop the platform from rocking on the hook at the top ??


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.i. crude sketch i know but is this sort of what you are saying

 

[pmkPE]

Actually I was thinking about supporting the underside of the platform using truss members made from aluminum angles similar to bar joist construction. The platform would be mechanically attached to the trusses which would act as fixed cantilevers coming off of the central shaft.

 

[3dboy]

full moment connections of either cantilever trusses or beams to the column should do the trick. You just have to check the torsional loads and or torsional rotation

 

[eski1]

hi
thanks so far for the reply's .You may have to educate me a little bit as i am mainly a machinist/welder and need a bit more explanation as to the likes of trusses etc ( sorry) .I still can't see how if the platform is suspended from a hook on a hoist , that when someone was to walk down one end of the platfrom it wouldn't start to pivot on the hook or am i being silly ??
cheers chris

 

[pmkPE]

The trusses are fixed (moment resistant) at the central column. a load at the extreme end of one truss is transferred back through the column and into a truss on the opposite side - the weight of the platform is then used to counterbalance, through the use of opposing trusses, the applied load in question.

It appears you need the services of a structural engineer. Do you have one in-house? If not check your yellow pages.

 

[eski1]

I will be getting in contact with a structual engineer after my i have had my quotation price agreed upon . Until then any costs that are incurred are mine to pay so i am reluctent at this point to involve a structual engineer although will be including a structual report fee in final quote. Does anyone have a rough sketch of what is being suggested with the trusses that they can send to me at
eski1@tiscali.co.uk so i can quote from this ( i hope this isn't being to cheeky
cheers
chris

 

[Ron]

esk1...if you must suspend this platform from a hook, you will find that the platform must have balanced loads or you will have rocking. Not much way to get around that.

Most of the comment has been based on the assumption that you could have a central pedestal column, fixed at the base, with cantilevered trusses extending radially outward to support the platform. This is different than your crane hook premise, but is the logical way to do such a platform.

If you must stay with the crane hook premise and no ground support of the platform, then perhaps you should consider that the mass of the platform must be greater than the load for stability, and you might also consider cable tie-backs to provide lateral stability of the platform.

In either case, a structural engineer should be involved. I think it prudent to involve the structural engineer early on as you do not want to quote a premise that could be significantly changed by the final design.