Pergolas, Gazebos, Awnings and misc gay/white trash home improvements for my porch. I need some mild engineering opinions.

[Troon_Patrol]

I've been planning on doing this for a while now, the porch is very exposed to rain and sun. I hate stepping outside and getting soaked in rainy season and I'd love to have a place to rig a hammock or a couple of hanging outdoor chairs or bench. Summer is practically here I'd love to host a few small get together in the summer months I'd want a light slope directing rain water out and away from the house maybe 10-20 degrees. Roughly 15' wide 10' deep and 10' tall to give a rough idea what I'm shooting for.

something very minimalist, no custom carpentry or simulated carpentry. I like steel especially If I'm adding ceiling based furniture.
fairly close to this

or

This style

I'd want to to go steel cause it's cheap strong I love to weld and would want to hang a hammock or chairs and a few potted plants. I would not trust these kits linked more than a 15 lb hanging potted plant.


if I were to rig a 50lb hanging chair center of a 15' square 1018 steel tube .250" wall wall thickness, as in 7'6" from the each corner, would that support a 200lb man safely? Would I be better to add a middle joist center of that 15' square beam?



Probably the easiest part would be a outdoor rated mesh polyurethane screen on all 3 exposed sides keeping mosquitos and flies away probably a magnetic strip I can wrap and fold out of the way when not in use.. I'm far more concerned with structural integrity low maintenance.

I'm leaning towards a project based around 4" steel square tube .250" wall thickness factory galvanized. Corrugated sheet metal at that 10-20 degree slope all painted after final fitting, possibly weather resistant slats on top IDK. I would consider myself a 8/10 welder 9/10 metal fabricator. Welding is not a concern for me although I might cheat and just use 3way corner brackets rather than all that angle cutting/matching with a band saw. that smells like 8-10 hours for 4 corners to get the perfect 3 way meet.


I keep seeing ridiculously overpriced high strength kits both made of wood/steel/aluminum. Overpriced as in a roughly 10'X15' wide 10' tall "kit" of either lumber (stained or even lacking stain) or square tube (steel or aluminum) MSRP is around $4,000 from what I can tell the brackets/materials should really be closer to $400 -$600 and they are not hard to find.


I'll post more later this is just an idea I'm playing with RN. I'm going for aesthetically pleasing/strong/simple/strong/low weather maintenance. I'm not interested in painting this thing every 2 years.

 

[Troon_Patrol]

Can anyone help nigga out? I used to have a link to very nice java based structural weight calculator, site is gone. Anyone who wants to point me to force/load steel calculator would be awesome. I have engineering questions.

Questions like a 16 foot square bar of 1018 mild steel .250" wall thickness supported at the lends horizontally, I want to put 300LBS of weight dead center using a 1/2" eye bolt ( eye bolt rated for obviously 300LB+ working load), will that safely handle this? This is for hanging furniture as previously stated. My white trash engineering gut says I'm good good around 1000lbs of weight, I always get a second opinion if lives are at risk in the slightest.

high definition illustration:

 

[Joshua Connor Tomar]

I need a pergola for grapes

 

[TardiX]

I crawled out of beauty parlor to hand calc this but then decided not to upload my handwriting online so bear with me.

Spoiler: math

The yield strength of your 1018 mild steel is ~=36,000 psi, lets go with 18,000 psi for a factor of safety of 2.

You have a 4"x4"x0.25" continuous square weldment/beam fixed at both ends with a center load.

Your moment of Inertia: (4^4-3.5^4)/12 = 8.83in^4
Your section modulus: 8.83in^4/2in = 4.41in^3
Yield strength is equal to bending moment/section modulus and bending moment (max) is equal to the max load * span / 4 considering a beam with a center load.

So rearranging those two formulas to find your max load you've got: 4.41in^3 * 18,000psi *4 / 192 in = 1,653.75 lbs

HOWEVER

This is what the material can safely handle. You have a continuous beam with a live center load and if you used that max load your deflection (0.952in btw) is beyond the allowable deflection for a beam that span (according the International Building Code standards at least).

Span/240 for live loads Span/360 for dead loads

So the max allowable deflection for your beam at 16' is 0.8in (with a live load).

Using that, your max load is:

Pmax = 0.8in(48*29,000,000*4.41in^3)/(192^3)
Pmax = 693 lbs

You can safely hang a live load of 693 lbs. (Factor of safety = 2)
Now this is for the beam, I'm not sure what your eye bolt is rated at.

Don't sue me.