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There's some fairly ugly wallpaper in our office restroom that's kind of a cloth material, which started me thinking. Why do we always strengthen walls from the inside - the studs? I've lived in San Francisco and seen very ugly earthquake retrofits where beams connect walls in order to strengthen them.
Here's my idea:
If a building's found to be in need of extra earthquake support, wallpaper all walls and ceilings using carbon fiber and resin. Such composites are very lightweight and very strong.
Shear wall basics.
http://www.mcvicker...wall/page001.htm#A1
17 Apr 03 | An interesting list of the various types, advantages and disadvantages of shear wall construction materials and techniques. [bristolz, Oct 04 2004, last modified Oct 21 2004]
A slightly broader reference on shear walls
http://www.mcvicker.com/vwall/page000.htm
Includes a review of shear wall history, diagrammatic shear wall examples and an explanation of shear loads and why they are so destructive. [bristolz, Oct 04 2004, last modified Oct 21 2004]
Fibrwrap Construction, Inc.
http://www.fibrwrapconstruction.com/
An earthquake retrofitter whose primary technique is wrapping existing structures with Kevlar and other composite fabrics and materials. [bristolz, Oct 04 2004, last modified Oct 21 2004]
Innovative Cost-Effective Building Retrofits to Resist Blast
http://216.239.33.1...r%22&hl=en&ie=UTF-8
[google translation from PDF to HTML] "...Recent innovative wall retrofit designs include the use of high strength fibers epoxied to the wall, such as Kevlar®, carbon, and E-glass fibers, as well as polyurea based spray-on elastomeric coatings..." [bristolz]
X-shaped cracking "typical" of severe earthquake damage
http://www.ngdc.noa...t/3/3_70_slide.html
Mexico City highrise. [bliss], were the cracks X-shaped like these? [bristolz, Oct 04 2004, last modified Oct 21 2004]
X-shaped cracking "typical" of severe earthquake damage
http://www.ngdc.noa...t/3/3_70_slide.html
Mexico City highrise. [bliss], were the cracks X-shaped like these? [bristolz, Oct 04 2004, last modified Oct 05 2004]
PAXCON
http://www.paxcon.com
PAXCON Anti-Terrorism Bomb Blast Protection [duroncrush, Oct 04 2004, last modified Oct 05 2004]
[link]
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Perhaps you should spray the mix on to avoid breaks at the paper seams? |
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I like the idea of steel mesh or composite wallpaper. Elegant. + Especially as a non-intrusive retrofitting technique. I wonder if the resin bond would be good enough to yield shear wall strength and, more importantly, whether the substrate the material was bonded to has the integrity sufficient to deliver rigidity to the underlying framing. |
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The retrofitter wouldn't have a lot of choice about what the substrate composition is. |
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Shear wall construction, where plywood sheeting is attached using screws or nails with a tight 3" spacing, to the frame at the inside corners of wood frame structures is, in essence, exoskeletal earthquake protection. |
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The sway braces of yore, diagonal pieces integrated into the framing itself, have been found to be nearly useless in an earthquake. |
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Here in Seattle, citing evidence from the LA/Northridge quake, building codes were changed in the mid-90s to require shear wall construction techniques on certain structures. We used the technique in the building of our home. |
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Other shear wall techniques are also used, depending on the ultimate use of the building and the building codes governing the construction. |
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Might make a nice replacement for siding, if it's not too expensive. |
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It occurs to me that a drywall product where a composite or carbon-fiber sheet is soundly integrated into the gypsum board itself might be an effective--albeit pricey--product, at least in new construction or stripped-to-the-studs remodeling. |
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[bris] I like it, am a bit concerned with fastening issues. Pounding a drywall nail through resin will create quite a weak point. Perhaps pre-fabricated holes at standard stud widths. Or just glue it to the wall - then use resin and composite tape to attach drywall together. The drywall will then be a seperate structure from the stud frame. Then again, this all seems like too much work compared to wallpapering. |
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There is a company that is doing this now for the air force. using spray on truck bed liner material http://www.paxcon.com |
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[bristolz] we disallow screws in shearwall applications as screws have the tendancey to shear when a strong force perpendicular to the screw is applied (nails tend to bend rather than shear). Nails through drywall are thought to render the drywall less capable of resisting shear, but they are commonly used with tighter nailing patterns as shearwalls.
I am not that familiar with carbon fiber resin, but it is interesting in this application. I am pretty sure that it would have to be mechanically connected to the stud walls as live & dead loads help to prevent wall deformation from wind & I think dynamic earthquake load.
Stud wall structures outperform masonry structures in eartquakes due to their ability to deform & return to original shape. I wonder if the carbon fiber will allow this? |
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Good points, [Zim]. Though carbon fiber's strength in both compression and tension should make up for it's rigidity, it is quite rigid. Not to say it has to be though, there are certainly softer resins and I'm sure you'd custimize your resin for this application. |
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Blow-on chopped fibre and resin over the existing wall material picture screws included. |
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Need to incorporate something in the fibers to create space that allows breathing. |
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They wrap concrete bridge colums with it now. |
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I beleive this is the opposite of the approach you want to take. Allowing the building to bend/flex/move is the key to earthquake survival. Structural rigidity bracing is like locking your arms out in a car crash. Yeah you will power through a 20mph crash and feel like a brute, but a 60MPH crash you try that and both arms are shattered. |
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