Cable Trellis Help 1

[XR250]

This is a plan view of a trellis proposed by a landscape architect. The lines are wire rope fastened to 14 ft. tall tube steel columns. Some will be guyed, some will be flag-poled. It is intended to have vines growing linearly on the cables. It will be installed at a high school.

Besides the ice, snow and vegetation loads, what else should I consider?

5 drunken teenagers hanging from each cable?
Full vegetation cover supporting a blanket of snow?

Not sure I am going to take the job due to:
1) Will likely lose my ass on it fee-wise
2) Will likely be hated by all involved as it will probably end up having to be a lot more stout than they are expecting which will probably blow the budget.
3) The liability of a “climbing structure” at a high school.
4) Way more detailing and analysis than I really feel like doing
Seems that most landscape architects in our area get away with building things like this without engineering or permits so they may have a rude awakening.

 

[SteelPE]

This looks like so architects wet dream. I am not sure where you are located, but if it's going to snow, it will certainly ice up. I think this "ice" load and show loads would be your worst case loading conditions. We sometimes have ice loads here when there is still leaves on the trees which tends to wreak havoc on everything. I know ASCE-7 has some information on ice, but it's been a while since I have been in that section.

1) If you do decide to move forward with he project just make sure the fee is large enough to make sure this isn't an issue.
2) More stout than they expected will also likely ruin the look they are thinking they are going to get. I find that they guys who "pretension" these cables just tend to wing it. So more stout is the direction I would go
3) Never going to stop the two legged animals.
4) You can build all of the "detailing" into item #1.

I would likely pass on the project too.... unless I had nothing to do.

 

[phamENG]

Oh come on...it looks like...fun...

I'd have a serious conversation with them about security and keeping kids off of it. There are things they can do to minimize the likelihood of an occurrence with the rest of the landscape design. That said, I'd still put one or two 250# point loads in the middle of the cable span. I wouldn't consider it for serviceability or even damage prevention - just life safety and preventing collapse. Make sure it's clear to your client and the end user that damage will be mommy and daddy's responsibility, not yours (I'd put it in the contract on the front end). Just do your part to make sure they don't die or seriously injure themselves. (And at that age they don't need to be drunk to do incredibly stupid things...).

For the liability piece, call your insurance provider. They've probably seen it before and can give you guidance.

 

[MIStructE_IRE]

I’ve done my fair share of these artwork things, like you i don’t know why i bother. You’re the best in the world because they think you’re going to solve all their problems. Then you’re the worst in the world when they realise what’s involved to make these things compliant. Sometimes art is best left uncomplicated by science.

However if you are going to give it a go, I’d certainly design for the drunken monkey bars situation!

 

[XR250]

Thanks for the suggestions.
I think i am going to pass on this. Got plenty of lower hanging fruit to choose from.

 

[XR250]

After my feedback, the Arch. has decided to go with a trellis constructed of steel sections instead of the tension elements.
Still a monkey bar situation, but much easier to design.