[GSBN] Compression (Digest, Vol 50, Issue 1)

[Derek Stearns Roff]

And tell us, Oh Northern One, if m. de Bouter doesn’t have a conveniently placed bit of collapsed bridge deck around to push against, what you might recommend to restrain the inflating tube, in order to transfer the pneumatic force to the bale wall, in the testing situation that he will likely face?  I agree that air pressure is a great way to get a lot of push per square unit, but you’ve got to have something to push against, nest paw? (as the biologists would say).

Having collapsed somewhere south of Santa Fe,
Derek

Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


On Jun 2, 2015, at 5:41 PM, RT <ArchiLogic at yahoo.ca<mailto:ArchiLogic at yahoo.ca>> wrote:

On Tue, 02 Jun 2015,  André de Bouter <contact at lamaisonenpaille.com<mailto:contact at lamaisonenpaille.com>> écrit

I'm looking for is a cheap, secure and rapid way to compress the SB
walls 'a whole lot', that can, preferably, be reproduced on building
sites. And if possible in a way that one can predifine the compression
load.

Cher Squeezit de Bouter;

When a massive concrete bridge deck has collapsed and emergency personnel  want an easy, safe and economical means to jack it up in order to rescue people trapped underneath, an "air jack" made by simply gluing up a piece of EPDM sheet to make a pillow that can be slid into a narrow space as little as a mere centimetre (before inflation) and then inflated, works very well.

Some simple arithmetic demonstrates how effective this method can be:

I typically inflate the tires in my "dog bike" (an MTB-style) to about 40 pounds per square inch (psi) (~ 275 kiloPascals (kPa), which is less than half the pressure of that typically used for road bike tires and easy to do with even the crappiest of manual tire pumps.

Looking at a 2-string bale wall (bales laid flat), a nominal 18 inches wide (0.45 metres),

40 psi x 18 inches (width) x 12 inches (length) =  8540 pounds of pressure applied per lineal foot of wall.


That is to say, if one used a tube inflated to 40 psi to apply pressure to the top of a bale wall, you would be applying 8540 lbs pressure to each  one foot length of wall (~ 125 kN/m).
I'll let you figure out how many straps or steel roads and at what frequency you'd have to use to achieve the same (if in fact you could do it all with those devices in any reasonable fashion).

Pretty easy to show whomever needs to see, what the applied stress is, when using an inflated bag or tube -- you just put a tire pressure gauge on the valve.

Years ago (in the 1990s ?) Bob Platts utilised this principle to make a system for pre-compressing bale walls as part of a CMHC (Canada Mortgage and Housing Corp) research project  I know that listmembers Habib Gonzales and John Glassford have owned/used that proprietary product/system and perhaps can offer some insights on how it could be improved or made simpler.

Bon chance, eh (?),  mon ami.
--
=== * ===
Rob "Stronzo di Nord" Tom ADT1
Kanata, Ontario, Canada
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