[TowerTalk] FW: MA-555 anchor bolts size

[Matt]

>From a copy of the 1986 US Tower Catalog:

The MA-550 tower by itself came shipped with (2) 1/2" x 10"anchor bolts and
a wall bracket.  It was not designed for free-standing installation.    It
was required to be "bracketed to the eve of a house roof" for support.

The MA-550 tower is completely self-supporting only when used with the
MAB-550 freestanding base or the MARB-550 freestanding rotor base - both
were hinged at the lower tower connection.   Both of these bases came
shipped with (4) 1" x 36" anchor bolts.

>From formerly published US Tower stress analysis calculations for MA series
towers conforming to 1997 UBC:

Anchor bolts were specified and stress calculated based on ASTM A36 anchor
bolts.  (Bolts I received for other US Tower models during the same time
period were shipped with large washers & nuts tack welded to the bottom)
The lower hinge bolts and upper split ring bolts were specified as ASTM A325
although the stress calculation was based on "ASTM A307 or better".

To my understanding, ASTM F1554 is the current anchor bolt standard.  These
are available in grade 36, 55, and 105, representing the yield strength in
ksi.  FYI - I have been using F1554 grade 55 in galvanized finish for recent
reinstallations.   They seem to be more readily available and the cost is
only marginally more than the grade 36.

Hope this helps.

Matt
KM5VI


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Jorge
Diez - CX6VM
Sent: Monday, September 16, 2013 10:53 AM
To: 'Tower Talk'
Subject: [TowerTalk] MA-555 anchor bolts size

Hello

 

Anyone know the ANCHOR BOLTS and NUTS size for the MA-55? This is an old
model, now I think is the same that MA-555

 

No answer from US Tower yet about that.

 

>From FAQ I see that 

 

QUESTION : Why has US Tower changed the anchor bolts from a J bolt to a
regular straight bolt? 

ANSWER : The anchor bolts were changed from the J bolts in the 1980s to
comply with changes in building codes at the time. Today the high strength
bolts come with a welded nut and washer on the end. 

 

 

So seems a regular one will be OK

 

Thanks,

Jorge

CX6VM/CW5W

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