Design of 10m Wall

[Joshiru]

My manager asked me to design a solid perimeter fence 10m high and 120m in length. This would be my first time to design "10m high" wall, I asked my manager if I could use a wire mesh to reduce wind load because the winds here goes from 200-250 kph. But he wanted it to be a solid wall (CHB). My question is what are the other option I can offer or What are the things I should consider for my computations??

 

[hokie66]

What does "CHB" mean?

 

[dik]

10m cantilevered wall... you'll likely need counterforts and structural steel for those wind velocities. Also control joints... Not trivial...

Dik

 

[spieng89]

Some sort of knee bracing may be needed for that height/wind pressure combination. Is diagonal bracing behind the wall an option?

 

[LittleInch]

I think CHB is Concrete Hollow Block or CMU.

Re-inforced concrete maybe, or perhaps a pyramid shaped CHB wall? or lots of long steel beams cast into the ground.

Other option - Find a better manager.

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

 

[oldestguy]

I note in the news that the US is building some high walls on the US-Mexican border. they appear to be pre-cast, so perhaps you should look into pre-casting or assembling them on the ground and then lifting. How they are braced is another question.

 

[dik]

OG: I was wondering if HC slabs could be used for a wall.

Dik

 

[racookpe1978]

10 meter high that long with that big a wind load? Not the assignment for a first-timer, particularly that long. Requires a PE sig for the lifting and rigging if a tilt-up, requires a LOT of scaffolding if built in-place.

200 - 250 kph cannot be "normal" but might be a hurricane/typhoon loading.

Try a shallow V-shape of alternating 20 meter long sections repeating down the whole length. Each V will reinforce the next against wind forces - you've got to plan for winds coming from either direction from the eye of the storm. Makes the foundation less expensive since the moment is resisted at both ends of each wall section.

 

[PEinc]

Is this for a real project? Sounds like he's giving you some busy work or just trying to see how inventive you are.

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[SlideRuleEra]

Simple, drive an HP10 every meter, or so (say about 121 HP total). The HP flanges are oriented parallel to the wall.
Put footings between piling to support blocks.
Fill in between the HP with reinforced CHB...done.

Glad there are no stated budget requirements... but is soil properties permit, may actually be a viable proposal.

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[Joshiru]

actually he is serious he already gave me the topographic survey of the lot and the deadline for my design. And by the way this wall will be used for the lot of a batching plant that our company owned. For the wind velocity of 250 kph it is the code provision of our structural code in that area I want to make it smaller but it is written on the book.

Thanks to everyone for all your suggestion and ideas. at least I have now an idea on what to consider.

 

[MotorCity]

Did he also give you a geotechnical report?

 

[charliealphabravo]

I agree this is not a trivial design from the perspective of either the foundation or the wall. You will want a geotechnical report. Also I can't see concrete masonry doing the job alone. It might work without too much complexity in the foundation if the wall plan has large zig/zags or a wave (square or sinusoidal).

 

[oldestguy]

Apparent;y you folks make the blocks for he wall. Why not look at what Sliderule era says and make pre-cast blocks, say at least one meter square, maybe 10 cm thick or more, lightly reinforced. Or full height length by 3 meters wide. Just drop them down in the space between H section flanges, using a crane and a jig for lifting them. Maybe a footing to keep them from settling a lot. Come to think of it, the H sections may not be quite the right spacing. So drive one H, set the pre-cast selection in the flange and then drive the next H, while securing it loosely to stay against slab edge, etc. That way you don't need a big crane for the pre=-cast. The H sections can be driven in sections, welded together.

 

[dik]

I've not encountered driving H piles with any precision... might look at driving them at 10' or 12' centres and building your wall proud of them, spanning horizontally...

Dik

 

[JLNJ]

The sound barriers along the Interstate have a system of cantilevered column elements (maybe 12' on center) with precast wall panels which fitting and spanning between columns.

I don't know for sure, but I think the foundations are drilled piers. This seems fairly efficient and simple to build.

The drilled piers will of course be significant with a 12' tributary area of a 33' tall cantilevered wall loading into them.

 

[IFRs]

Shoot - just drive sheet piles and be done with it.

 

[SlideRuleEra]

For the HP proposal, soil properties could determine the HP spacing. Overturning moment for the cantilevered HP is directly proportional to pile spacing. Wind pressure will probably be > 50 PSF.

I picked 1 meter HP spacing just as an illustration that should work (with no calculations). I expect, with proper calculations, HP spacing can be increased. The HP10 size was just for example, too. A larger size could be made to work and allow additional construction tolerance.

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[PEinc]

You might want to look at the PennDOT standard drawings for high sound walls. See the following links.

http://www.dot.state.pa.us/public/Bureaus/BOPD/Bridge/2016/BD/BD677M.pdf

http://www.dot.state.pa.us/public/Bureaus/BOPD/Bridge/2016/BD/BD676M.pdf

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