Are the anchor bolts loose (rattling in the hole)? If not, I suspect they are still good. I also think the additional gussets will strengthen the frame enough to solve your problem. No opinion about your last question, a structural engineer may be along to offer some advice.

 

Use a come-a-long to pull things back into shape, and add 45˚ braces at the four corners, ideally lapping onto the rafters and the posts, and bolted.
Ground anchors probably OK enough if nothing is actually broken after being straightened.
Angle braces much stronger than another horizontal member.
X bracing on the house side is another possibility that would be quite strong.

 

+1

 

You can add some hefty beams left-to-right on that photo, aligned with the columns, then some 45 degree braces. So 3 beams with braces on each connection.

I don't know about your anchor bolts. What footing is down there? IS there a footing or any foundation? Just a slab? Anchor bolt type and embedment? I suppose if they didn't fail, it's okay to reuse them.

 

Footings aren't meant to resist the shear your pergola experienced. The pergola has a massive amount of leverage to move the footings, as you found out. The best example of how to resist such forces is how they now sheet a house with OSB to resist the shear load from wind and earthquakes. Before OSB they would cut a diagonal into the studs and put in a piece of 1x6 or 1x8 to resist shear. 45° brackets/braces will help but will take away from the beauty of your pergola. From what I can tell, it looks like the beams on top of the posts moved with the posts to some extent, while the joists above the beams are simply toe-nailed into the beams, so there was separation between the beams and the joists. At least your joists look like they are still level! If the joists had been securely fastened to the beams I don't think you would have had an issue.

If you used something like the Simpson TBE4 to connect the joists to the beams, you might not have seen your pergola shift like it did as the joists would have helped resist the shear just the same as a large 45° brace. I just plugged a couple of parameters into the Simpson website to find something that resists the loads, so don't use the bracket I suggested it is just an example. I would contact Simpson directly or consult a structural engineer, but I think you should be able to find some Simpson (or similar) metal brackets that will keep your pergola upright without needing to change the look of your pergola with 45° braces.

 

Footings aren't meant to resist the shear your pergola experienced. The pergola has a massive amount of leverage to move the footings, as you found out. The best example of how to resist such forces is how they now sheet a house with OSB to resist the shear load from wind and earthquakes. Before OSB they would cut a diagonal into the studs and put in a piece of 1x6 or 1x8 to resist shear. 45° brackets/braces will help but will take away from the beauty of your pergola. From what I can tell, it looks like the beams on top of the posts moved with the posts to some extent, while the joists above the beams are simply toe-nailed into the beams, so there was separation between the beams and the joists. At least your joists look like they are still level! If the joists had been securely fastened to the beams I don't think you would have had an issue.

If you used something like the Simpson TBE4 to connect the joists to the beams, you might not have seen your pergola shift like it did as the joists would have helped resist the shear just the same as a large 45° brace. I just plugged a couple of parameters into the Simpson website to find something that resists the loads, so don't use the bracket I suggested it is just an example. I would contact Simpson directly or consult a structural engineer, but I think you should be able to find some Simpson (or similar) metal brackets that will keep your pergola upright without needing to change the look of your pergola with 45° braces.

That's a weird statement.. They had ply before OSB... they could have used ply.. The better builders still use diagonal studs to resist shear. when they don't they are cutting costs. Since there will be sheathing anyway.

 

Thanks all for the feedback. Here is the post base that was used - 6x6 Ironwood Post Base - OZCO Building Products and it is secured to a poured concrete pier with a 5/8" bolt with sleeve. We got it stood up with temporary bracing to secure it and it is level, but am still debating if it should all come down, install new (perhaps bigger) post bases and then rebuild (probably with at least 45 corners on all four sides. Thanks again!

 

Thanks all for the feedback. Here is the post base that was used - 6x6 Ironwood Post Base - OZCO Building Products and it is secured to a poured concrete pier with a 5/8" bolt with sleeve. We got it stood up with temporary bracing to secure it and it is level, but am still debating if it should all come down, install new (perhaps bigger) post bases and then rebuild (probably with at least 45 corners on all four sides. Thanks again! View attachment 3878562

Great job bringing that to it's home place. So in my post I mentioned adding beams aligned with the columns... because the light purlins don't have any (or much) rotational restraint. Addition beams with 45 degree braces will create portal frames in the left-to-right direction. You currently don't have any frame action in that direction, which is why it rotated out of shape.

Not sure why previous post mentioned the footings can't resist the shear and the fittings rotated. The anchor bolts are what resist the shear and transfer it to the foundation. And it's obvious the foundation (whatever it is) didn't rotate.

I'm curious what kind of wind gusts you had. Have you checked the weather data?

 

Floresc, if you look at the original post, you can see, either the brackets at the footing moved or the footings moved. Look closely and you can see the black bracket isn't plumb and leans in the same direction as the posts. So, either the footings moved or the brackets bent. If the footings resisted shear, why would you need to add extra structure up above? I'll agree that with a large enough footing you can resist shear, but it seems to me in this case, the footings aren't large enough to resist the forces put on the pergola by the wind.

 

Um, you are right. Something looks wrong on that photo. But on the last photo by OP, everything looks good down there. 🤔 Maybe a closeup photo and clarification from OP is what we need here.

So I was thinking that there was originally some moment at the base of the column. The thing was trying to be a large moment frame, although a weak one lacking stiffness. I can't make out what is the connection down there, but your typical wood base plate connections such as Simpson can't transfer moment, only shear.

At least in design every wood base connection such as these are modeled analytically as pinned (shear transfer only, no moment transfer). And of course, axial transfer too.

By adding beams and braces up at the top, you only transfer shear at the base. The only moment would be resisted my the framing members and braces added.

Well, even 84 MPH is a very strong wind event! Sadly, just about all these pergolas that I see built around here are built like OPs pergola. 🫣

 

Diagonal bracing and you should be good

wood braces for pergola - Google Search

 

I take back my previous comment about the bases. Those had minimal strength resisting bending to start, and now are worse. They were not appropriate for a large unbraced structure, even 'tho they show exactly that in their literature. I would lift up and move the entire structure over, and assess & probably replace the post bases with column bases that are cast into concrete footings I would also refasten all the upper connections with 4" or longer structural screws, including drilling through the post/beam metal and toe-screwing with large screws. I don't like that kind of post cap because it prevents the wood pieces from being actually fastened together.
I'm guessing that two people could have pushed the pergola over just like that by trying only moderately hard.
Sorry for the not- positive review.

 

One more quick clarification, here is a quick pic of the footing at the max level it leaned before we got it stood back up. The 5/8" bolt was still in concrete with no apparent cracking, but it certainly could be loose. I am leaning towards leaving it in place and adding in additional bracing and a wall structure along the house side to prevent further issues in the future. The other option is to deconstruct, add bigger anchors and then build it back. I am not convinced jacking up each leg to fix is the easier option.

 

Unless the base plate deformed the anchor bolt is now loose in the hole or possibly broken.

 

Hi - I am new to the community and I have a couple questions about my pergola project. We completed our pergola, but a recent windstorm has me needing to better support it. I am trying to understand -
1. Since the pergola was leaning but the anchor bolts in the concrete held, do they need to be replaced or do they still have enough holding power to be reliable?
2. I want to add some additional bracing and am thinking either a 45-degree bracket on the two sides that do not currently have it, or a 4x4 beam wedged horizontally (at the same height as the 45 degree brackets would be). Is one stronger than the other? View attachment 3878516

Hi - I am new to the community and I have a couple questions about my pergola project. We completed our pergola, but a recent windstorm has me needing to better support it. I am trying to understand -
1. Since the pergola was leaning but the anchor bolts in the concrete held, do they need to be replaced or do they still have enough holding power to be reliable?
2. I want to add some additional bracing and am thinking either a 45-degree bracket on the two sides that do not currently have it, or a 4x4 beam wedged horizontally (at the same height as the 45 degree brackets would be). Is one stronger than the other? View attachment 3878516

Take it down and start over. Your anchor points have been compromised and need to be replaced. Obviously you did not do any diagonal bracing on two sides. Also could have used diagonal braces on the two center posts. Helped a friend who went thru the same problem on an open carport structure. He suffered more, first snow load took out both cars parked under it. I had my dad who was a journeyman millwright carpenter come take a look at it after it collapsed. He told us to set new connections on the concrete slab and put in the proper diagonals on the four corners and the center uprights.

 

I used these on a carport recently. They have high load ratings. The rebar and footings spec'd by the engineer were kind of insane, but it allowed for a pretty open plan.

MPBZ

The new patent-pending MPBZ is the first post base specifically designed to provide moment resistance for columns or posts and features an innovative overlapping sleeve design to resist rotation.

www.strongtie.com

 

lookin good. id suggest runnin diags all 4 top corners that dont have them having them hit the vertical posts where the other 45 diags meet .

 

The leaning tower of pergola.
Apologizes

 

"Deleted"

 

Don't know what would've withstood a microburst of 84 mph wind other than burying the posts in ground beneath freeze line and concreted in. Is that a kit? Did you talk to OEM? Need 4 more gussets, knee braces, for sure.

 

Just to say, triangles are your friend when it comes to structural construction, I am not sure about your footings although if it were mine, I would take the brackets off for a thorough inspection of the concrete footing, bolting and brackets. If the metal brackets bent that would be a big enough concern to me to replace them. When Hurricane Harvey came through here in 2017 we had sustained wind of 155+, the edge of the eye wall was just about a mile up the coast from our house. The 38x48 pole barn turned shop that my 2 teenage boys and myself built in 1989 was still standing(no corrugated roof tin left)I was sure proud of our construction. Your issue is kinda like turning wood on a lathe, you haven’t screwed up completely until you run out of wood. We all make mistakes, the thing afterwards is to make sure we learned from it and do not repeat them. Chin up and get back at it You got this! Just saying…….Smokey

 

Like all the others, 45 degree kickers.

If you were doing this from scratch 15 inch diameter footings about 2.5 feet deep with the PT posts embedded 2 feet.
Pole buildings are built that way.

 

Once you bury wood in concrete you start its demise...

 

For the OP, it looks like your brackets pulled away from the footing. The photos don't really show the connection, but I'm guessing an anchor bolt in the concrete footing goes through the center of the post bracket. I bet if you took the post off you would see that the metal bracket's base bent and pulled away from the anchor bolt and that is why in your last post you see daylight between the concrete and the bottom of the bracket. I agree with those who say take it apart to inspect the footings and the brackets then rebuild with additional 45° bracing.

I also agree with those that have said don't put posts in concrete. The concrete holds the water around the post which accelerates the demise of the posts. I've seen fence posts rot off in a couple of years when they were embedded in concrete. For your pergola I'd stick with brackets that either bolt to or are designed to be embedded in concrete so the post remains above the surrounding surface. For a fence, if you want to put posts in the ground without brackets, you need to dig the hole deeper than the part of the post below grade by about 1/3, then fill the bottom of the hole with gravel, and then put the post in the ground and backfill with gravel. The deep hole and the gravel let water drain away from the post so the bottom of the post dries more quickly which reduces the chance for rot.

Or.........
You could just leave the pergola as is and pour 4 huge dead-man anchors, about 8' away at each corner of the pergola and a couple of feet below the surface, then anchor the pergola with heavy steel cable to the anchors and massive eyebolts at each corner of the pergola, the pergola wouldn't go anywhere and you wouldn't have to rebuild. Of course, with this arrangement, after a couple of beers, late at night, you will take your head off as you wander around the yard, but at least the pergola won't move!

 

You could see a structural engineer to design footing size and a steel bolt on bracket that would embed in the concrete footing.
HD galvanize bracket, incised ground contact PT posts.

I was a structural engineer for 39 yrs. Always got accused of over designing.

 

Hi - just a quick update on the resolution to the pergola problems. I added 4x4 kickers to the opposite corners, added in a new back wall along the house to further prevent shifting, removed the legs (one at a time) and used epoxy to set new bolts in the existing holes and added some steel joist supports (probably more decorative than actual support, but any steel helps). Thanks all for your advice and feedback!

 

Looks great and most likely fixed the issue. Congratulations

 

We just had something similar happen and decided to go with some 45 degree gusset brackets from Bjorn Woodworks.