Load-bearing capacity of aluminum L-beam

[tommib]

I don't have experience with any of this you are talking about and cannot calculate deflection and similar things. Despite this, I thought I would come up with a suggestion that I haven't seen anyone else mention.

Couldn't the deck be built as a two-stage unit? First, three suitable steel pipes/beams are automatically pushed over the pool from the long side and jack into the supports on the opposite long side. These then only need to bear their own weight when they are extended. Then, when the beams lock on the opposite side, the pool cover is extended over them. The span between beams then becomes just over two meters, much more manageable than eight.

Disadvantages of this are:
1. Much more complex mechanics
2. There must be holes in the long side where the beams are
3. Perhaps the most difficult problem, is there space for a beam with "overlength" on the fixed side? Even if it only bears its own weight, it is not insignificant and will want to tip into the pool.

 

[Huggedugge1]

a clarification….

If you use three support beams (span 220cm between the support beams) in your construction, you can manage with 45x170 on the joists.

If you use two support beams (span 440cm between the support beams) in your construction, you ABSOLUTELY CANNOT manage with 45x170 on the joists.

Now I'm considering the solution with a T-beam. Then it will be 1 beam at the front, then replace the joists with 170*45 in 4 m lengths.

Can I not even manage with cc 45 between the joists and if every other one is reinforced with 3 mm plate?

 

[Erik Lindroos]

We had a welder here from a company. He had an app and entered a bunch of variables and said I needed an HEA 250. He himself thought it turned out bulky and said there should be more streamlined solutions.

He might have had stricter demands on deflection or otherwise stricter requirements, so I don't want to say he was wrong.

 

[Huggedugge1]

I have no experience with any of this you're talking about and can't calculate deflection and the like. Despite this, I thought I’d propose an idea I haven't seen anyone else mention.

Couldn't the deck be built as a two-part unit? First, three suitable steel pipes/beams would automatically slide over the pool from the long side and latch into supports on the opposite long side. They would only need to bear their own weight when sliding out. Then, once the beams have locked on the opposite side, the pool cover would slide out over them. The span between beams would then be just over two meters, much nicer than eight.

Disadvantages of this are
1. Significantly more complex mechanics
2. There must be holes in the long side where the beams are
3. Perhaps the most difficult problem, is there room for a beam with "overlength" on the fixed side? Even if it only bears its own weight, it's not insignificant, and it will want to tip into the pool.

Oh, that sounds a bit advanced. The pool is made of concrete, so making modifications to it is not possible. If I understood you correctly?

Three sides stand on a reinforced deck. The deck rolls in under a "deck" that is about 3 m. Then the deck becomes like a step. So there's no space over 3 m.

 

[Derbyboy]

Now I'm considering the solution with a T-beam. Then it will be 1 beam at the front, then replace the floor joists with 170*45 in 4 m lengths.

Can I manage it even with cc 45 between the floor joists and if you reinforce every other one with 3 mm sheet metal?

No, I really DON'T believe so.

 

[Huggedugge1]

No, I really DON'T THINK so.

So you think I should also add a center beam?

 

[tommib]

Oh, that sounds a bit advanced. The pool is made of concrete, so making any alterations to it is not possible. If I understood you correctly?

Three sides are on a reinforced deck. The deck rolls under a "deck" that is about 3 m. Then the deck becomes like a step. So there is no space over 3 m.

No, I meant that the supports would be recessed into the deck on the opposite side. However, if there is not more than 3 m of space on the fixed side, then it is not possible.

 

[Derbyboy]

So you suggest I should add a central beam as well?

No, I would avoid a central beam like the plague, that is, I would only want to custom-make ONE beam and then run floor joists for the entire length (440 cm).

 

[Erik Lindroos]

a clarification….

If you use three supporting beams (span 220cm between the beams) in your construction, you can manage with 45x170 for the joists.

If you use two supporting beams (span 440cm between the beams) in your construction, you ABSOLUTELY CANNOT manage with 45x170 for the joists.

Now I'm more uncertain about which modulus of elasticity you should practically use for wood, but with 10000 N/mm^2 (as Bernieberg used earlier), it actually isn't that bad. I calculate that 14 parallel (approx. 600 cc) 170x45 would bend down 5.5 mm under a distributed load of 1500 kg. Then it would probably feel a bit shaky if you walk around the middle. And I think it feels long with over a 4 m span.

Haven't calculated the strength.

 

[Huggedugge1]

Beam options:

VKR 200x100x8. Quite heavy (35.1 kg per meter, 9 meters will be 316 kg). According to Stena Steel, 9 meters cost around 15 kkr. According to @Violina, it can be cambered relatively easily (although it should of course be done by someone with a bit of experience).

IPE 200: The most weight-efficient shape (22.4 kg/m, 9 m weighs 202 kg). Stena's price for 9 meters is approximately 9 kkr. According to @Violina, somewhat trickier to camber.

Custom made à la @Bernieberg. Don't know what it would cost, but neat solution if it works.

Stainless steel, expect 8-10 times higher price.

Standard vs. cambered/prechorded. Hard for me to say in terms of price, but cambered is good in more ways. Avoids sagging, which gives a bit more leeway for the wooden joists to flex. Because they will flex a bit.

Addition: If 200 mm in height doesn't work, you can choose HEA 180. Heavy like VKR (35.5 kg/m) but stronger (less sagging).

For pools, acid-resistant steel is usually used. Do you know if Stena Steel has such a plate in 3mm and roughly what it costs? Can they also deliver customized lengths?

 

[Huggedugge1]

No, I would try to avoid a central beam like the plague, i.e., I would just want to custom-make ONE beam and then run floor joists across the entire length (440 cm).

What dimension would you use for the floor joists? If you reinforce them with metal plates?

 

[Derbyboy]

Now I am more unsure about which modulus of elasticity to practically use for wood, but with 10000 N/mm^2 (as Bernieberg used earlier) it's actually not so bad. I calculate that 14 parallel (about cc 600) 170x45 would bend down 5.5 mm under a distributed load of 1500 kg. Then it would probably feel a bit wobbly if you walk around in the middle. And I think it feels long with over 4 m span.

Have not calculated the strength.

See my earlier post (#260) deflection 26mm on a 245. How can you get it to 5mm for a 170??

 

[Erik Lindroos]

See my earlier post, deflection 26mm on a 245. How can you get it to 5mm for a 170??

What load have you used? I don't see it. And then my elasticity value might be way off, I don't have good information on that.

 

[Huggedugge1]

See my previous post, deflection 26mm on a 245. How can you get it to 5mm for a 170??

245 won't work. Have 23.5 cm to insert the tire in height.

 

[Derbyboy]

Which load have you driven? I don't see that. And then my elasticity value might be way off, I don't have good data on it.

I'm using the program that svensk trä has.