Diagonal Brace on Gate - Which Way?

[Turbo]

I'm making a gate as above. The heel is 50x50x2.5 rhs & the outer hoop is dia 42x2.5 tube (an old gate frame). The middle upright will be replaced with 25x25x2 rhs & there will be a horizontal bar half way up, again in 25x25x2 rhs.

This will be sheeted in light gauge box profile & hung on a girder. I'm worried about the gate drooping over time so I'm adding diagonal braces in 25x25x2 rhs but not sure of the best way.

There are 4 options I can think of ie like v or ^ or / / or \ \ .

The gate is 110" long & 48" high.

 

[chris pruteanu]

Either will work into making it sturdier. The best way to stiffen a structure is to triangulate everything- a series of triangles inside the frames will give massive strength from a structural point of view.

 

[Pete.]

Either way will do if it's securely welded in but I always favour high at the hinge end as it means less load on the top tube. Two parallel diagonals will put less weld heat in at the centre node.

 

[Eric the chicken]

You could also fit a supporting wheel if the ground over which the gate swings is level.

 

[eLuSiVeMiTe]

High at latch side to low at hinge side
Been done like that on ledge and brace doors for a very long time for good reason.

 

[Dee J]

Tension rod or compression strut? Old style railway crossing gates use the former, ledged and braced doors use the latter. A thin strip, rod or cable, high at the hinge side works well provide the ends are secured well and can even be adjustable. Struts low at the hinge side need to be stiff enough not to flex under compression. Both work if the gate is designed appropriately.

 

[Spark plug]

i was told many years ago by an old engineer I worked with to use steel braces in tension and wood braces in compression, to make best use of the mechanical properties of each material.

 

[eLuSiVeMiTe]

i was told many years ago by an old engineer I worked with to use steel braces in tension and wood braces in compression, to make best use of the mechanical properties of each material.

Good to know I gave a carpenters answer as thats my trade lol.
Will rememeber that for future use.

 

[zzr1200]

Being as you have a centre upright.

Low on the hinge side to the top on the centre upright that way the diagonal is under compression, then low on the centre upright up to the top of the latch side. This way the loading in the middle of the gate is transferred to the bottom hinge via the diagonal the second half of the gate transfers the loading via the diagonal then along the bottom tube to the hinge.

 

[rtbcomp]

High at latch side to low at hinge side
Been done like that on ledge and brace doors for a very long time for good reason.

Which is?

 

[eLuSiVeMiTe]

Which is?

The weight from the unsupported stile is supported by the lower hinges.
Braced the other way the unsupported stile is hanging and applying force to the top hinge

 

[Gareth J]

In reality, there are lots of options. In steel, unless you're using very thin rod or wire rope, you can use it in compression or tension.

The easiest to do yourself is flat uprights (farthest gate to the right) but it's not always about what's easiest so pick what you think looks best and, so long as it's not too hard to do, go with that!

 

[rtbcomp]

The weight from the unsupported stile is supported by the lower hinges (B).
Braced the other way (A) the unsupported stile is hanging and applying force to the top hinge

I would have thought that the door would act the same as an unbraced piece of solid wood, and the forces on the hinges the same in both cases. However because it's made up of separate pieces there will be an anti-clockwise moment acting on the brace, which in case A will pull the boards together and in case B pull them apart, making any sagging worse.

I made such a door more than 20 years ago and couldn't make up my mind which way to brace it, so I braced the top half one way and the bottom the other with a horizontal across the centre and it's been perfect ever since.

 

[Gareth J]

In wood, I think compression is used not so much because wood is stronger in compression than tension (don't think it is anyhow) but because it's hard to "fix" wood in place in tension. In compression, it can be wedged in place and hopefully stay there better without drooping.

Steel can be welded in and the anchor points are far more secure. Especially in tension (compared with wood)

 

[Maker]

I don't think it matters.

 

[armalites]

I would say in welded steel it doesn't really make any difference but in a wooden door with diagonal braces inbetween stiles/rails then you want it low on the hinge side that way if there is any movement it will self tigthen as the brace is under compression the other way round the brace could put out of the corner. On a gate post it means the load would be concentrated on a part of the post that has the least amount of leverage.

 

[eLuSiVeMiTe]

View attachment 179848

I would have thought that the door would act the same as an unbraced piece of solid wood, and the forces on the hinges the same in both cases. However because it's made up of separate pieces there will be an anti-clockwise moment acting on the brace, which in case A will pull the boards together and in case B pull them apart, making any sagging worse.

I made such a door more than 20 years ago and couldn't make up my mind which way to brace it, so I braced the top half one way and the bottom the other with a horizontal across the centre and it's been perfect ever since.

More like this. Same principle for an unframed ledge and brace door.
Just transferring the force back to the post and giving the wood nowhere to.

I concur with @zzr1200 with the inverted V makes sense in this instance

 

[MoreWellie]

I concur with @zzr1200 with the inverted V makes sense in this instance

I don't think he said that, I read his answer as (Hinge side) /|/ (latch side)

although I don't know that it makes a lot of difference, I just wanted to get in on a fun discussion

 

[eLuSiVeMiTe]

I don't think he said that, I read his answer as (Hinge side) /|/ (latch side)

although I don't know that it makes a lot of difference, I just wanted to get in on a fun discussion

Lol. Misread his post.
In that case I dont concur

 

[Pete.]

The trouble with gates is people swing on them and climb over them. If the diagonal brace is low on the hinge end, any weight put on the gate is held only be the top tube, including the weight of the brace. If the brace is high on the hinge end then any weight put on the gate is shared by the top tube and the brace together.