Advice Required : Pergola is it strong enough

[Neil Swann]

Uprights are 3 x 3 posts x 4 rebated for the cross beam 18" buried in postcrete . Main cross beams 6 x 2 attached by M10 bolts. 8 @ 5 x 2 above skew nailed and 8@2 x 2 atop that. We thought it a nice idea later to put a swing on the main beam for the grandkids 4-6 yrs weight approx 20-25kgs. I note some lateral movement because they are quite energetic when swinging. I did check first using a crash test dummy(me) without exerting that much energy without apparrent issues.
So my thoughts are thus: Re-install 5 x 2s with a notch to make more resistant to the forces applied laterally. Is this sufficient or is the whole structure not safe for it's new additinal use?
Regards
Neil

 

[sunnybob]

Find a way to put a diagonal brace across the front to back posts.

 

[Neil Swann]

Unfortunately I don't think that is possible. The sides are made up of two DIY trellis panels the frame of which is only 2 x 2 and nowhere to provide sufficient strength for a brace as suggested. I could use 3 x 3s as additional bracing between the front and back uprights but it won't look right to my mind. Thanks for your input.
Regards
Neil

 

[sunnybob]

Without a diagonal brace, it will move, end of story.
Only you can decide if the movement will be dangerous or not.

 

[MikeG.]

Bracing is the issue, but you also have a fundamental flaw in how it is attached to the ground. It will rot off at the point where the post enters the concrete, and it may do it pretty quickly. If there is movement, it may be because one or more of the posts are already weakening there.

 

[Neil Swann]

So will notching the beams running at 90° to the main cross beams provide enough bracing to minimise lateral movement?
Regards
Neil

 

[sunnybob]

No

 

[Stanleymonkey]

We have a similar-ish pergola. I wouldn't let the kids climb or swing off it. Children also have that lovely ability to come up with strange ways to use swings that we can't even imagine!

Buy or make a proper swing - much more fun!

 

[El Barto]

I don't see why it can't be braced... curved braces would look quite nice and fairly unobtrusive I reckon.

 

[Neil Swann]

OK thanks for the advice all. Purpose built swing seems to be the most sensible option.
Regards
Neil