Thread: Ramp

Originally Posted by Marc

Also will build the truss/handrail demountable so that I can handle moving the sections around on my own and installing it. \

340kg forgetting about the wood thats going to weigh in at just under 1 ton in steel. So I'd say no to using the same wall thickness. I assume the hand rail is also a truss so I'm not so sure about making it removable.

Originally Posted by Marc

I am not sure what sort of aluminium they use for this,

Grade 6063-T5 or equivalent.

Have you had things hot dipped before?

Stuart

OK, so how do I convert that plan to steel?
I looked up the RHS 150x50x3 and 4 meters at 9k a meter its just 36k. Where it is going to be installed I have no access to a crane so I have to install one member at the time. The 2 beams first, then the handrail/truss and last the floor. The truss can be bolted to the beam it will still do the same job.

I had stuff hot dip before but never this big. Why do you ask?

Originally Posted by Marc

OK, so how do I convert that plan to steel?
I looked up the RHS 150x50x3 and 4 meters at 9k a meter its just 36k. Where it is going to be installed I have no access to a crane so I have to install one member at the time. The 2 beams first, then the handrail/truss and last the floor. The truss can be bolted to the beam it will still do the same job.

I had stuff hot dip before but never this big. Why do you ask?

I think what Stuart may be asking is are you aware of the cost involved in Hot Dip Galvanizing, it is normally calculated by weight.

Given the relatively small size of the ramp, at a guess I reckon that 2mm wall steel rhs would be perfectly adequate. There are several design features that could work against you in galvanised construction. First thing I would do is replace the 50X50 angle for the deck side supports with flat bar - cheaper and quicker to set up and fabricate. If you use angle iron, you will need to space it at least 1mm out from the rhs to allow the zinc to flow into the gap so as to prevent rust between the sections. I probably would use flat bar even if constructing out of ally.
Are you going to make individual sections that then bolt together for installation? If so, then channel sections may be better than rhs from a sealing and thus corrosion perspective.
It will pay to check on the size of your chosen galvaniser's bath. Most are long, reasonably deep, but fairly narrow.
If this is to be installed in a public setting then be careful of legalities etc.

Thank you very much for all the replies. Yes, I know galvo is per kilo. There is a company in Yagoona that charges from memory $1.07 a kilo. the bath is 7 or 9 meters long I believe but I never asked the width. I will ask now that you mentioned it.

I agree with the angle for the flooring, clearly a flat bar is easier.
I was thinking in making the handrail with the 3 post and the 2 diagonals in one piece and have 3 tenons sticking up from the bearer to slide the post on and bolt to them.

I am not familiar with C channel, what would be the equivalent to RHS 150x50x2 and 100x50x2?
I was trying to find a table that tells the load bearing capacity of steel sections to no avail.

Originally Posted by Marc

OK, so how do I convert that plan to steel?

Well now that's the tricky part isn't it.
Sides as is in steel are over 90kgs. Now I assume you could halve that easy enough, but then you want to be able to bolt it together which is going to add some weight back. So you're going to want to break that down and your gong to end up with a Meccano set. I'm sure its doable

Originally Posted by Techo1

I think what Stuart may be asking is are you aware of the cost involved in Hot Dip Galvanizing, it is normally calculated by weight.

Cost isnt my problem Its more about not having any closed sections and "good drainage"

Stuart

p.s.There is something way out with our weighs.(maybe leaving the wood out wasn't such a good idea lol)

Oh I see ... forgot about that. If I weld the ends of the RH shut, There is a problem with the heat of the bath ... yes ... I could leave the ends completely open really but that would take away some stenght where it needs it most ... partially open? Drill a hole? I can ask the galvo guy he will tell me I suppose.

What if I do the two beams at 150x50x3 at 36k each = 72
Central post and two diagonals 100x50x3 at 35k each = 70
outside post and handrail in 100x50x2 at 27k each = 54 ____________ 196 total plus some bits and pieces say 210 in total plus the wood, however this means I can maneuver one beam at the time no problems at 36 kilo each. Once in position I can bolt on each of the trusses. If I split the central post and diagonals from the handrail and the outside posts I am home and hosed.
The wood I prefer hardwood to treated pine. The difference is 80 kilo in total, but it is irrelevant once the steel side of the ramp is mounted to the anchoring and pontoon, I can screw the floor on one by one.
I will then have to counterbalance the pontoon for listing. The weight of hardwood floor is 170K Treated pine 90.
The total weight of the ramp with my on the run calculation should be around 380k with hardwood floor or 300 with TP floor. That means I have to make a block of 150k concrete to level the pontoon.

Of course this is all assuming the steel sizes are the right one for the job.

Why would you need to cantilever the pontoon, is it going to be suspended off one end, into nowhere or is it going on to land? I did write a lengthy reply, but lost it, would be nice to be able to save it with a draft button. Will write it out again later.
Kryn

The ramp purpose is to access the pontoon and to keep it steady. It goes from an existing concrete slab to the side of the pontoon. The p is 6mx2m and the weight of the ramp will make it list to one side. Because the floats are built across and not along, I can't do what is usually done and that is to fill the opposit row of floats with water. I'll have to weight down the other side. Of course I could add buoyancy under the ramp side with an extra floater but that is more complicated

Hello Marc,
Do you have a MIG welder or access to one? If so, aluminium is no harder to mig weld than steel in the thicker sizes. Aluminium construction may not be any more expensive than the cost and problems that go with galvanising, and would solve a weight problem. I see a lot of ally used for such structures and assume the cost/benefit sum outweighs galvanised steel. Regards,
Combustor.

Well ... to be honest never considered it. Yes I have a mig, cigweld trans mig 250. I will have to get a pure argon cylinder and what else? New torch or just new tips? And the aluminium wire of course. How do I grind my beginners welding? Cutting? Mm that would be some experience. Don't even know who sells aluminium RHS. Do you think that I can just improvise like that?
It is a very simple structure.

Then there is another alternative. Forget the truss structure. Build the ramp as a flat self supporting ramp and add the handrail later for safety reasons not for structural reasons. And that brings me back to my size conundrum. What size RHS in steel would be ok for a 4m span?

Mig for welding that thickness Al .... good luck with that . http://www.wikihow.com/Mig-Weld-Aluminum . this site will give you some clues.
Better to get a Tig ac/dc pulse machine or pay some one to weld it for you

Well, yes, that is another consideration, I don't know if my transformer MIG 250 amp can even do the job. I thought it would. It's on a 32 amp 240V line but hey, what do I know, never even tried.

As far as getting someone to weld it up for me ... not such a bad idea. If my machine is capable, I can hire a local welder to come and weld it up for me. What is the going salary rate for a welder in casual employment?

Anyway, not the best day to consider all the possible alternatives of my little project.
Merry Christmas to all particularly those who are so keen to contribute to my random thoughts

Merry Christmas and a prosperous new year.
Marc

Originally Posted by Marc

I will have to get a pure argon cylinder and what else? New torch or just new tips?

Different feed rollers to suit the ally wire, larger tip to allow for the wire expansion when hot. Most likely a new liner as well, especially if the unit has been used a lot and the liner has crap from the steel wire throughout its length.