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Re: WOOD CONNECTOR: Prying Force

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Bill,

Refer to section 9.2 of the 1997 NDS for the withdrawal values of lag screws
and don't forget to apply the appropriate adjustment factors (including
depth penetration factor).

I'm not sure what you mean exactly by "prying force" but I'm pretty sure
that section 9.3 of the 1997 NDS is what you need.  You'll find wood to
metal lag screw connections along with combined lateral and withdrawal
loads.

Figure out your resultant withdrawal force and it's direction with respect
to the horizontal plane.  Equation 9.3-6 on page 79 will do the rest (not
quite but you know what I mean).

If a detail is required you might want to pay attention to section 9.1.2 of
the 1997 NDS.  It will tell you how big to make your pre-drilled holes
(based on your wood species; G).

Personally I always take into account the field fabrication flaws/unknowns
and add a little bit.  Typically one inch in length minimum!

I hope this helps!

Best Regards,

Brian McMahon, E.I.T.
----- Original Message -----
From: "Bill Polhemus" <bill(--nospam--at)polhemus.cc>
To: "SEAINT" <seaint(--nospam--at)seaint.org>; <aec-residential(--nospam--at)polhemus.cc>
Sent: Thursday, May 31, 2001 10:18 PM
Subject: WOOD CONNECTOR: Prying Force


> I'm calculating the allowable force for pull out of a lag screw holding a
> bracket. Is there a prescribed way to calculate "prying force" if any?
>
> William L. Polhemus, Jr., P.E.
> Polhemus Engineering Company
> Katy, Texas
> Phone 281-492-2251
> Fax 281-492-8203
>
>
>
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