[TowerTalk] FW: Base Anchor Bolts

[Matt]

The link below shows some diagrams of different anchor bolt types.  Which
ones do you have?   The last HDX572 design calculations I have from UST
specify (6) 1" by 27" ASTM F1554, grade 55 (55,000 psi yield), with type E
block arrangement using a 2" square x 5/8" thick A-36 (36,000 psi yield)
steel block welded to the top die of the nut.   Min embedment was 21".  This
arrangement with a 5.5' x 5.5' x 7.5' footing was rated at 55,000 ft lbs
overturning moment in 100 psf soil.

http://stanley-sales.com/media/e5b0d8a7677e8f11ffff89b7ffffe904.jpg

I know that the ASCE revised the their standards a few years back resulting
in more conservative designs for anchor bolt pull-out strength.   We
routinely run computer analysis for anchor pull-out these days considering
not only the embedment but also the overall geometry of the footing,  The
last two shipments of grade 55  anchor bolts I purchased from my anchor
supplier were fabricated to the new ASTM F1554  standard and were Type F
with the heavy square block sandwiched between two welded nuts.   FYI -
bolts I received from UST under the old design standards were ASTM A36
(36,000 psi) with Type D washer & nut welded to the base. 

I have never heard of an anchor bolt pull-put failure on a UST.   I would be
curious if anyone on the reflector has?

Hope this helps,

Matt
KM5VI

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Mike
Fahmie
Sent: Saturday, November 02, 2013 8:49 AM
To: towertalk at contesting.com
Subject: [TowerTalk] Base Anchor Bolts

My HDX-572MDPL came with 1" anchor bolts with a welded nut at the bottom. 
The nut diameter is only slightly larger than the shaft so I am considering
the addition of a heavy washer wired against the nut to increase the
'grab'.  Is this a good idea?

How does the welded nut approach compare with 'L' shaped anchor rods?

-Mike-
WA6ZTY
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