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Re: Cracks in Blocks in Fire Tower

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My guess is corrosion.  If so, cutting the bolts off at the face of the wall
will not stop the corrosion process and progressive damage will probably
continue.  The product of steel corrosion has much more volume than the
steel from which is comes, it is capable of developing tremendous pressure.

Nels Roselund
Structural Engineer
South San Gabriel, CA

----- Original Message -----
From: "Gary Hodgson & Associates" <ghodgson(--nospam--at)>
To: <seaint(--nospam--at)>
Sent: Wednesday, August 18, 2004 11:13 AM
Subject: Cracks in Blocks in Fire Tower

| 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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