solar pergola on pavement, only weighted down

[42OhmsPA]

I like it. I'm sure it would be sturdy but I'd add more ballast. ..
How much additional weight would you gain using solid blocks instead of cinder blocks on the layers that don't have beams running through them?
I'd bet that would add a significant amount, you could also add a row or two in the front and back to give it some extra resistance to tipping. (I'm not an engineer and would still run some numbers but I think it would be plenty sturdy, if wind tipped it you have bigger issues to deal with)

I've seen the wind do some crazy things and I don't even live in a windy area.

 

[CableGuy]

@42OhmsPA I did consider the solid blocks, but I have to consider the labor stacking, and unstacking later. I can pickup 2 of this style of block easily, one with each hand. (this is actually easier than picking up 1 and walking a few feet) Positioning a single block is also a lot easier with the holes for grip. Volume is not a concern here, so the ability to grip and move this style seems like a worthy trade off. Actually, i would not want the height of the wall to be shorter. This height means no one will step over and trip, and is visible from inside a vehicle when parking. Shorter walls might present more of a risk. I also like the idea of the blocks not being able to fall, however unlikely. The ballast is only beneficial if the end of the 2x6 through them doesn't fail at game time. Solid blocks on top of an open block row would roughly triple the stress on each 2x6 end in the row below it.

This rending is 38lbs each x 72/pallet x 4 pallets = 10,944lbs. i added 2 more panels putting the array at 7020w. I will likely forfeit the ability to park our box trailer under this and add longer angle braces to the front opening also. It makes more sense to park our cars in the shade anyways.

An empty shipping container weighs 8000lbs, and I'm reading that needs 130mph winds to blow over. Once i'm sure how to do these calculations, I think i will find that I can reduce the amount of blocks. I'm happy with a base plan that allows for easily sourced modular ballast, does not interfere with parking, does not penetrate the pavement, and won't be a nightmare to take apart and move.

thanks for the input!

 

[Zwy]

It's not going to blow over, and I have mentioned: at least 4 times pentrating the pavement is not part of the solution.

I've read your responses, you have your mind made up, just do it.

There is this thing called leverage, some know how it works, some don't.

At the very least, you gain educational experience.

 

[Supervstech]

I've read your responses, you have your mind made up, just do it.

There is this thing called leverage, some know how it works, some don't.

At the very least, you gain educational experience.

I do hope he gets insurance, liability at minimum...
Inspection may educate him.

 

[CableGuy]

I've read your responses, you have your mind made up, just do it.

There is this thing called leverage, some know how it works, some don't.

At the very least, you gain educational experience.

I only have my mind made up that a weighted solution can work, and it's possible to do it from a space perspective with concrete blocks.

If you think that task is impossible, that's all you need to say. You have offered nothing constructive for the restrictions I have for the project so stop commenting.

 

[CableGuy]

The concensus seems to be ground penetrating solutions are better for obvious reasons, and although I would have to agree that to be true in most situations, the deciding factor is the amount of force/direction needed to for a ground anchor to fail.

For the amount of suggestions I am seeing for ground anchors, without specifics on soil and depth of these solutions, how can one solution be declared superior, or even safe?

I guess what I am asking is does anyone have data or a resource on various ground penetrating soltuions the strength they provide for comparison purposes?

For example, someone suggested an auger style which I agree would be strong, but without depth and size of the device, and soil type, the force it can endure is a pretty big variable.

 

[Bluedog225]

The solution requires math. Math is hard. Trolling is easy.

 

[Bluedog225]

That probably needed an

 

[Supervstech]

Free Online Wind Load Calculator | SkyCiv

SkyCiv Wind Load Calculator displays the wind speed by location and the required wind pressures to be applied to your building or structure.

skyciv.com

 

[CableGuy]

The solution requires math. Math is hard. Trolling is easy.

Very excited to do the math, but i'm not going to bother on calculating a solution that I can't install.

 

[Doggydogworld]

Lift is q*S*CL, where q is dynamic pressure = 1/2 rho V^2. With CL aka coefficient of lift = 1 a 60 mph wind produces a bit less than 10 lbs of lift per square foot. That's 3200 lb for your 320 square foot "wing".

A 90 mph wind would be 2.25x that much, or 7200 lb. A 120 mph wind would be 4x or 12,800 lb.

 

[Supervstech]

Lift is q*S*CL, where q is dynamic pressure = 1/2 rho V^2. With CL aka coefficient of lift = 1 a 60 mph wind produces a bit less than 10 lbs of lift per square foot. That's 3200 lb for your 320 square foot "wing".

A 90 mph wind would be 2.25x that much, or 7200 lb. A 120 mph wind would be 4x or 12,800 lb.

Likely structure angle and surface direction play a part.
A fence or suitable windbreak built on one side would reduct lift effect, but introduce side wind forces.
Idk...

 

[sparrowhawk]

I am looking to build an array in a small parking lot. it will only be in service 2-3 years, and i don't want to disturb the pavement. the top is 27.5ft x 11.5ft, with panels almost flat roughly 8.5ft above ground. it will be pitched slightly but only for runoff reasons. Certainly classified as temporary and not grid-tied.

There's 72 cinderblocks per pallet, @ 33lbs per block, so 2 pallets is over 4,600lbs. they fit nicely between the posts in double rows of 10 with a 2x6 PT slid between them which is bolted through the 4x4 posts at each end. see below...

3 layers in the center (60 blocks) 2000lbs or 1000lbs per center post
2 layers (40 blocks) is 1300lbs on each end, or 650lbs per corner.

thoughts? see image below

There's one thing that may or may not be an issue and that is the possibility of the bricks sinking slightly into the asphalt. That is assuming when you say pavement it's made out of asphalt. I bring this up because asphalt does soften when heated so depending how warm it gets there and the sheer concentrated weight of the bricks may cause some deformation.
What made think of this was when I was a teenager living in Phoenix AZ. and during one summer day I witnessed an 18 wheeler pull up to a stop light and before it had turned green he had sunk into the asphalt enough that he had become stuck and was unable to pull out of it under his own power. Now of course that was during 115 degree AZ heat but I think 80 to 90 degree heat might very well allow bricks to sink if left there over time.

 

[CableGuy]

There's one thing that may or may not be an issue and that is the possibility of the bricks sinking slightly into the asphalt. That is assuming when you say pavement it's made out of asphalt. I bring this up because asphalt does soften when heated so depending how warm it gets there and the sheer concentrated weight of the bricks may cause some deformation.
What made think of this was when I was a teenager living in Phoenix AZ. and during one summer day I witnessed an 18 wheeler pull up to a stop light and before it had turned green he had sunk into the asphalt enough that he had become stuck and was unable to pull out of it under his own power. Now of course that was during 115 degree AZ heat but I think 80 to 90 degree heat might very well allow bricks to sink if left there over time.

No you're right, it hit's 100F here in summer, asphalt temps can get hot. It's faded, but still. Good call. I should spread the weight out a bit...

 

[42OhmsPA]

Here's a random thought. Build the floor into the structure. Extra ballast when equipment is in it.
Would be fairly simple to build a base with tube steel and thin plate. (space so fork pockets are built in).
Stack everything on the bases when you're done and haul it away.

 

[CableGuy]

Likely structure angle and surface direction play a part.
A fence or suitable windbreak built on one side would reduct lift effect, but introduce side wind forces.
Idk...

There isnt a wind break to the sides, but there is a concrete building behind it that will create uplift.

Which leads me to my next point, that the structure should be similar to a deck from a footing requirement, which is why I am curious how much uplift such footings can counter. I have seen countless decks where the posts just sit on the concrete, unattached.

 

[CableGuy]

@42OhmsPA I like the idea but i've never worked with tube steel.

Now that i'm into 4 pallet territory of blocks needing delivery, I might as well consider just getting 2x2x6 retaining wall blocks or similar with the rebar lift point delivered before I make the wood frame. I was going to build the frame then add weight then add panels, but if I started with the large concrete blocks I could ask the neighbor to push them into place before the frame goes up with his bobcat.

The 2x2x6 blocks weight 3500lbs each.

 

[CableGuy]

Lift is q*S*CL, where q is dynamic pressure = 1/2 rho V^2. With CL aka coefficient of lift = 1 a 60 mph wind produces a bit less than 10 lbs of lift per square foot. That's 3200 lb for your 320 square foot "wing".

A 90 mph wind would be 2.25x that much, or 7200 lb. A 120 mph wind would be 4x or 12,800 lb.

Thank you. I know there's more to this as a whole but this is very helpful for perspective on possible solutions.

 

[Hedges]

I only have my mind made up that a weighted solution can work, and it's possible to do it from a space perspective with concrete blocks.

If you think that task is impossible, that's all you need to say. You have offered nothing constructive for the restrictions I have for the project so stop commenting.

Ballast can be made to work.

My SWAG is that the cinderblocks shown in your rendering are insufficient.
More substantial concrete weights suitably tethered to the structure could do it. Struts so that tension on cable has to dead-lift the weights, rather than dragging them, might significantly reduce the weight. required.

Not sure how well it works having openings to allow wind between flat panels.
I had thought Solyndra's claim to fame was that sun at an angle hits same area of collector (because they paid to put material around a cylinder, therefore presenting smaller area than same surface area flat panel.)
But I learned from my old boss, who was invited to run the company and declined, that their key feature was that wind could pass between the tubes. So it could be placed on commercial roofs with ballast, no penetrations.

 

[CableGuy]

Ballast can be made to work.

My SWAG is that the cinderblocks shown in your rendering are insufficient.
More substantial concrete weights suitably tethered to the structure could do it. Struts so that tension on cable has to dead-lift the weights, rather than dragging them, might significantly reduce the weight. required.

Not sure how well it works having openings to allow wind between flat panels.
I had thought Solyndra's claim to fame was that sun at an angle hits same area of collector (because they paid to put material around a cylinder, therefore presenting smaller area than same surface area flat panel.)
But I learned from my old boss, who was invited to run the company and declined, that their key feature was that wind could pass between the tubes. So it could be placed on commercial roofs with ballast, no penetrations.

Thanks. I am already now leaning towards larger concrete blocks if the weight recommendations are what's needed.

I am under the impression uplift is the biggest concern with a mostly flat array, and if the blocks are directly below the top of the frame edges, i'm not sure I know what you mean with the struts?