How to make a Garden bridge from pvc?

No. Or maybe. It relies the span and intent of use.

So, If the actual amount of resources you use will be much greater than the resources for a Pontoon Boat, and you do not need this bridge for heavy duty industrial purposes as transporting > 500lbs entails, You may want to look into:

How to make a Pontoon Boat out of PVC

Before you start planning your bridge as permanent rather than mobile.

Also, you may want to note that as far as creating a more permanent bridge [that does not become a pontoon boat in a flood] via 3 inch PVC filled with concrete or quikrete is not always the best choice, although concrete makes it alot more sturdy, this also is dramatically more heavy than that PVC 40 and moreso jointing is ordinarily designed to bear: 24/7.

For insights kick the PVC beneath your sink.

Thus, you may want to go with Copper Pipe or Rubber Tubings instead, which can fill or fill paŕtially with concrete, [with rubber tube you force the concrete through with clever use of a dowel or wooden nickel and per necessity a hose].

Those can more bear the weight, handle chains led through them, and also tolerates the application of FlexSeal Clear used as a sealant/protectant.

The finest part of copper pipes is that alike PVC, all the fitings are premade, To extents, building a 20 foot ladder for a fire exit from your roof, is indeed quite easy to do.

If you can make a ladder, which without concrete to firm that copper is moreso pipes used as a cover for chainlink, of course, you can be sure that you can also make a bridge, when you do add the concrete/quickrete to a quality chain in a 2" or 3" pipe.

The pro of rubber tubing is: Any fittings you cannot make out of the rubber, can be made out of concrete.

You must get a higher grade rubber though, for insights, try to put Concrete into a Balloon [or 7], and compare that to a coke can, charlie tuna can, or any galvanized steel pipe you might have some scrap of lying around.

Quite simply, kids do not play kick the concrete balloon, they play kick the can.

My opinion on PVC outside of indoor plumbing? It is not much better than that aforesaid concrete ballon filled with helium, beneath a belief it might become lightweight.

PVC when used outside the scope of purpose that it was designed, is as bad or worst than anything else placed outside of the scope of the purpose it was designed.

As far as a bridge goes, as the cost of each PVC pipe is more than 2 qty 2×4 of the same length, and no matter you use, you yet have to shoestring your chain through them just like you would a rope ladder, it becomes almost senseless to use PVC for a bridge rather than a pontoon boat.

The icing on that cake and deal breaker is that: To Drill a PVC, reduces the integrity of the structure of the PVC more than drilling a 2×4 reduces the integrity of the structure of the 2×4, very few managers at retail, if informed that you want to drill PVC to then let children and adults walk over these, and sometimes drive a riding mower over these too, actually let you so do without a quick consultation on that fact of:

Bridges need structural integrity that PVC alone when

drilled does not provide.

Again, putting concrete in PVC may seem to improve this, but: Better Alternatives at same price or less [Aluminum flashing among these] exist which with concrete, more withstand drilling.

I would not build the bridge from pvc unless it is going to be decorative only, and no one is going to walk on it.

If it is going to be walked on then build the frame and railings out of pressure treated lumber then use pvc faux bamboo to make it look like actual bamboo by sliding the pvc over the railing posts, cutting it in half and screwing it to the sides of the frame to mask the wood and so forth. You can use a construction adhesive labeled for outdoor applications to add rope to make it look like you tied the frame together if you want it to look rustic and cover where the edges of the pvc show.

Here is a tutorial on how to make the pvc look like bamboo:

https://www.instructables.com/id/Faux-Bamboo/

In breif, PVC is not recommended for anything weight bearing that needs to be drilled. Not limited to a weight bearing bridge. Once you drill it, it will be more prone to breakage.

If it is not a weight bearing bridge but a Gnome bridge that is an entirely different topic, you can use what you want, there are no codes against Accidentally Killing a Gnome.

You suggest you want it to look like Bamboo.

Bamboo rarely if ever grows beyond a 2 inch diameter.

Concrete that is weightbearing is rarely beneath 3".

Do you see the conflict here?

So the old trick of: 'when you need something better than Pipe, often filling the pipe with concrete is how you get it' does not apply to any pipe beneath 3" diameter.

Concrete beneath 3 inches is not 'Load Bearing'.

Both of My Concrete Porches, uses 6 inches since 1953, and we have had no trouble with:

Refrigerators, Concretes, Building Materials, Couches,

Chairs, Ovens, Furnitures, Beds, etc: Heavy Weights

This method does not assist in 2" or Less Diameter PVC you will need to create that Bamboo Effect you desire, want or feel you deserve.

If I were you, to be blunt and honest, you are better off incorporating that Bamboo effect, only via Bamboo Shades, and any craft you make of Thin PVC painted Bamboo Green, that you attach to a Much More Sturdy Bridge than Ever PVC can provide.

I say this sincerely and having experience dealing with Code, and Code Officers:

You can decorate any Structure any way you like. Staple

Or Glue whatever you like, wherever you like, and the

Code Officer and Police will not Care, provided it is not a

vulgarity, offensive or nudes.

However once you start Incorporating Decorations as a

Substitute for Items Essential to Structural Stability, and

Structural Integrity, that is what any good and Dutious

Code Officer and Patrolmen minds, and this especially

applies on a load bearing bridge which might in certain

emergency situations qualify as an emergency exit,

escape route or integrate into an Emergency Evacuation

Plan.

This means: you do not substitute an Architecture with a Decor, Ever, nor should you expect a Decor to withstand all the elements and stresses that an Architecture will.

What you are expecting to do, to actually do that to a T, is debatedly not even legal nor safe to even do, but instead: ill-advised.

You need to discuss that Safety with your Code Officer or Mayor.

Rest assured, he as I will agree:

The bamboo look is Fine for a Decoration.

But It will neither work nor approve as the Primary

Structure of an Emergency Exit, which any load bearing

bridge indeed is in a time of emergency, an exit.

When that is the case, that a Bamboo look is only a decor, you may as well attach Planter Boxes to a Real bridge and just grow bamboo [recommended].