Max.length of 3 meter unbuttresed double-brick wall ?

Posted by on November 15, 2007, 11:59 pm

Here is S.Africa, where they had a burglary over a 1 meter high wall,
they have highened the wall to 3 m. with old-used [but good quality]
bricks which they had lying around.

I have heard of free-standing walls collapsing and killing persons, eg.
in a storm.

Apparently free-standing walls should have 'posts' built from eg.
4-bricks at specified intervals ?

Since the government building inspection department is probably
non-functional since the recent 'liberation take over', I'd like
some international advice.

The bricks are British imperial sized: 75x 110x 230 mm.
The wall is double bricked, with 'cross-layed' at the top.

Thanks for any input,

==Chris Glur.

Posted by Michael Bulatovich on November 16, 2007, 8:22 am

> Here is S.Africa, where they had a burglary over a 1 meter high wall,
> they have highened the wall to 3 m. with old-used [but good quality]
> bricks which they had lying around.
> I have heard of free-standing walls collapsing and killing persons, eg.
> in a storm.

It happens.

> Apparently free-standing walls should have 'posts' built from eg.
> 4-bricks at specified intervals ?

"Pilasters."

> Since the government building inspection department is probably
> non-functional since the recent 'liberation take over', I'd like
> some international advice.
> The bricks are British imperial sized: 75x 110x 230 mm.
> The wall is double bricked, with 'cross-layed' at the top.
> Thanks for any input,

I recently had to convince a client that this was a concern for an interior
wall he did not want to reinforce with steel. If you had a wall fall on you,
I'm sure you'd rather it was a gypsum partition.

Another variable to consider is the straight length of the masonry wall.
Walls with jogs, spaced closely enough, buttress themselves. (Our code here
calls for intersecting walls or buttresses (pilasters) at no more than 36x
the wall thickness for non-loadbearing walls.) There is the precedent of the
traditional serpentine wall to consider, too, and which deals with the
problem of overturning and wall slenderness:
http://commons.wikimedia.org/wiki/Image:Serpentine_wall.jpg

At 3m high and presumably 230 thickness you are at 13x thickness which is a
bit higher than my engineer would permit...If you are concerned, you should
have a pro look at it, or stay away from it, especially in a good wind or if
people are operating vehicles near it.
--

MichaelB
www.michaelbulatovich.ca

Posted by 3D Peruna on November 16, 2007, 9:05 am

Michael Bulatovich wrote:

> Another variable to consider is the straight length of the masonry wall.
> Walls with jogs, spaced closely enough, buttress themselves. (Our code here
> calls for intersecting walls or buttresses (pilasters) at no more than 36x
> the wall thickness for non-loadbearing walls.) There is the precedent of the
> traditional serpentine wall to consider, too, and which deals with the
> problem of overturning and wall slenderness:
> http://commons.wikimedia.org/wiki/Image:Serpentine_wall.jpg

I was going to reference him to the serpentine wall at the St. Louis,
MO, Zoo. It's tall, but wavy to keep it standing up...

Posted by Michael Bulatovich on November 16, 2007, 9:58 am

> Michael Bulatovich wrote:

>> Another variable to consider is the straight length of the masonry wall.
>> Walls with jogs, spaced closely enough, buttress themselves. (Our code
>> here calls for intersecting walls or buttresses (pilasters) at no more
>> than 36x the wall thickness for non-loadbearing walls.) There is the
>> precedent of the traditional serpentine wall to consider, too, and which
>> deals with the problem of overturning and wall slenderness:
>> http://commons.wikimedia.org/wiki/Image:Serpentine_wall.jpg

> I was going to reference him to the serpentine wall at the St. Louis, MO,
> Zoo. It's tall, but wavy to keep it standing up...

Sure you were. ;)

Posted by Troppo on November 17, 2007, 6:31 am

>> Here is S.Africa, where they had a burglary over a 1 meter high wall,
>> they have highened the wall to 3 m. with old-used [but good quality]
>> bricks which they had lying around.
>> I have heard of free-standing walls collapsing and killing persons,
>> eg. in a storm.

>
> It happens.
>

>> Apparently free-standing walls should have 'posts' built from eg.
>> 4-bricks at specified intervals ?

>
> "Pilasters."
>

>> Since the government building inspection department is probably
>> non-functional since the recent 'liberation take over', I'd like
>> some international advice.
>> The bricks are British imperial sized: 75x 110x 230 mm.
>> The wall is double bricked, with 'cross-layed' at the top.
>> [...]

>
> Another variable to consider is the straight length of the masonry
> wall. Walls with jogs, spaced closely enough, buttress themselves.
> (Our code here calls for intersecting walls or buttresses (pilasters)
> at no more than 36x the wall thickness for non-loadbearing walls.)

The UK codes have something similar - can't remember the ratio, 25 years
since I last had to use it - but that code didn't have seismic
requirements, or much in the way of wind-loading for free-standing, as I
recall.

Avoidance of pilasters would require some form of reinforced bond beam
coping, maybe post-tensioned rods, foundation to coping at ?? spacing.
Easier to do it in hollow masonry block. Keep the bricks for decorative
paving. Or crush into pea-gravel for the same purpose :-)

> At 3m high and presumably 230 thickness you are at 13x thickness which
> is a bit higher than my engineer would permit...If you are concerned,
> you should have a pro look at it, or stay away from it, especially in
> a good wind or if people are operating vehicles near it.

Once saw an example of something like this - free-standing wall at the
side of a fire station. The wall was post-tensioned, eg threaded rods
from top to foundation. A fire truck is capable of packing a punch ...

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