I've been asked to design a tempora

[TrussBridgeboy]

I've been asked to design a temporary bridge for a 2" waterline to span 145'. Rather than do such a large structure for such a small thing, I was thinking a suspension cable set might be more appropriate. Does anyone know who does that sort of thing? I've seen those types of structures done for long span pipes but I've no idea where to direct my customer.

 

[r13]

Suggest to search the internet for suspension cable contractors. Here is one, but I don't know if they are interested in your project or not. Link Or you might ask local scaffold contractor.

Actually, for such a small weight, it would be much cheaper to design several simple hanging/upholding posts along the route.

 

[dhengr]

TrussBridgeboy:
I suspect you are right, that a 145’ rigid/spanning bridge for that 2” temporary water pipe, would be a real dog. The right kind of pipe, bending strength, connections, etc. would probably tolerate being hung, at essentially the same shape, as a wire rope (or chain) catenary. Short adjustable vert. hangers would make the final support and shape adjustment btwn. the two systems. You would also need some means of guying the system to the ground at several locations to limit movements from lateral loads like wind or EQ’s, etc. This would seem to be something btwn. a suspension bridge and a tension structure (tension/fabric roofs, tents, and the like). Maybe high tension, high voltage, electric transmission cable statics and control has something to offer. They have some novel means of controlling the vibration and movement of their cables, vib. dampers and the like. So those tension structures might be another ref. source. Another issue will be the pipe movement and bending, final shape (fittings, expansion/contraction, a movement joint) at each end. This could be an interesting project and nice change of pace from the old std. temp. bridge.

 

[XR250]

Be sure the pipe used has rigid joints and not push-on joints (designed for subgrade use). Otherwise, it could turn into a pretzel once pressurized.

 

[KootK]

Maybe explore agricultural systems designers? The situation where I've seen similar structures is on farms where they 3D truss the pipe itself in a rather clever way. Even if your pipe can't be the compression strut, maybe it could be strapped to whatever is. See my sketch below in which I've butchered the concept pretty badly with my limited Bluebeam skills.

 

[JStephen]

I didn't see much to help, but ran across this site:

https://bridgebrothers.com/pipe-bridges/

Koot's description sounds like these units:

https://www.youtube.com/watch?v=ND4ZDNud5i4

("Central Pivot" irrigation system)

 

[HTURKAK]

I think the structural engineering solutions ( cable stayed form, truss supporting structure, cable structures..) will not be economic and safe solutions for this case.

I will suggest ; thrust boring system which provides accurate horizontal bore beneath the road without trenching . You may leave 4 in sleeve pipe for future use for utility lines , communication cables etc .However the responsible authority will be asked to give permit and my opinion ,their approach will be positive.

You may search at your local area for the expert groups having trust boring machine. The concept is shown at below picture found at web:

 

[TrussBridgeboy]

Thanks everyone for your replies. I had searched the 'net for a person or company to do such a structure (the suspension cables) but didn't have much success. I believe the pipe is now along a bridge that's being rebuilt over a creek, thus the temporary nature. We are a competitor to Bridge Brothers so that's not a viable alternative. Our structures will work fine, just overkill.

 

[dauwerda]

I thought KootK was referring more to something like this:

I have seen what the OP is talking about, but I don't know anyone who specializes in it. I imagine it would be very similar to the design used when hanging utility (coax, fiber, telephone, etc) wires from steel cables on utility poles.

 

[r13]

Is this temporary line going to cross a water way? If so, can floating objects in the water way be acceptable? You may want to let us know how the route looks - any obstructions, length on land, highway crossing...etc.

 

[KootK]

I thought KootK was referring more to something like this

That's exactly what I was referring to.

 

[LittleInch]

Why not use the pipe as the suspension "wire" itself.

You should be able to work out a sag and axial force and just span 45m itself.

something like this

https://www.mtu.edu/peacecorps/programs/civil/pdfs/lyle-stone-thesis-final.pdf

but modified.

Even if you need to strap a cable to the pipe to take some of the axial force / weight , just build two towers and do a simple span.

Who cares if it sags?

A 2" welded steel pipe is very flexible and if you make it thick enough would have a high axial strength.

If it's windy add a few guides to stop it swaying.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rb1957]

KISS it ?

another day in paradise, or is paradise one day closer ?

 

[BAretired]

The attached file is an informative and interesting article, a Design Guide for similar river and gully crossings in the Dominican Republic. It was submitted as a Master of Science thesis to Michigan Technological University in 2006.

https://www.mtu.edu/peacecorps/programs/civil/pdfs/lyle-stone-thesis-final.pdf

BA

 

[bridgebuster]

Similar to what LittleInch suggested, you could run the water pipe inside. A larger pipe. I did that for a pipe bridge in a landfill. The contractor had to run a small gas line over a 90' gully. We put it inside a steel pipe.