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Re: Cracks in Blocks in Fire Tower

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Thanks for everybody's replies to my original post below.

Some further info:  All of the eyebolts were stainless steel so 
corrosion was not a factor and the anchors were all embedded 5" into 
the wall.  They were set in the inside vertical face of the parapet 
and the top of the parapet was covered with a 1/4" bent plate to 
allow the ropes to move smoothly without abrasion.

However, one 3/4" eye bolt holding a chaing at an opening in the 
parapet also has cracking, but of a different geometry thant the 
radial cracking at the rapelling anchors.

I am inclined to believe a combination of loading, impact and severe 
temperature changes may have been the problem.  Temperatures in 
Niagara Falls can range from -20F in winter to +110F in summer.  The 
fire dept. did not want thru bolts at the time of construction as the 
tower can be seen by the public on 3 sides.  The 4th side faces a 
cemetary whose residents are remarkably easy going.  The fire dept. 
has now decided that thru-bolts will be acceptable to them.

cheers,
Gary Hodgson,
Niagara Falls, ON



On 18 Aug 2004 at 14:13, seaint(--nospam--at)seaint.org wrote:

> Approximately 10 years ago, I designed a 4 storey fire training tower
> for the City of Niagara Falls.  The construction was 8" reinforced
> block with a 42" high parapet.  In the parapet I embedded 5/8" eye
> bolts to be used for anchoring rapelling ropes for climbing down the
> tower.  Almost every one of theses bolts has radial cracks around the
> bolt shank circulating out 2" to 4".  The fire department cut off the
> eye bolts to stop their use.  There are still U bolts in the roof slab
> so they can still train.  However, they want to have the eye bolts or
> an equivalent re-installed in order to have different means of
> anchoring for training.  I guess not all buildings are the same.  
> 
> Does anyone have any suggestions as to the cause of the cracks in the
> block or alternative means of anchorage to the parapet wall?  Photos
> are available if anybody's interested.
> 
> thanks,
> Gary Hodgson
> Niagara Falls, ON



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