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RE: Drilled pier cracks

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Rich,
 
Are there any inspection or construction logs?
 
Is the tower leaning? 
 
There are some ultrasonic methods,  Jay Shiltstone in Dallas has done some this for me in the past.
 
The only 180 bends I've seen are ACI hooks, but not on anchor bolts.
 
 
Hmm, interesting problem. 
 
Arvel
-----Original Message-----
From: Rich Lewis [mailto:seaint02(--nospam--at)lewisengineering.com]
Sent: Tuesday, June 21, 2005 2:18 PM
To: seaint(--nospam--at)seaint.org
Subject: Drilled pier cracks

I was sent some pictures of a concrete drilled pier for a cell phone tower.  The top of one of 3 piers is cracked.  The cracks radiate from the anchor bolt group.  There is a somewhat circular crack that surrounds the bolts and then about 8-12 cracks radiate out to the edge.  It appears the anchor bolts have been pulled up slightly.  I am told the top surface is out of level on this particular pier, with the crown in the middle.

 

I have a copy of some of the original calculations of the pier.  There are 10-1” dia. Bolts per leg, 78” long.  The note says it is to have a 180 degree bend.  I have never seen an anchor bolt with a 180 degree bend.  Is this common for this type of application?

 

In order to repair this I think I need to establish the extent of cracking and integrity of the pier.  Is there a reasonable way to establish this?  Is there an ultrasonic type test that can be run?  What kind of results would it tell me?  The pier is 6 ft. in diameter and 41 ft. deep.

 

Anyone ever run into a repair like this before?  Any suggestions on a fix?  If I could establish that the pier was sound down a certain depth form the top I could request demolishing the bad section and repouring concrete if it wasn’t too deep.  Another solution would be to drill 2 piers adjacent to this one and tie the existing leg into the new piers.  I would assume that taking the tower down is not an option right now.

 

Thanks for any suggestions.

 

Rich