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# Re: Bolt force in round column

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Bolt force in round column
• From: Daryl Richardson <h.d.richardson(--nospam--at)shaw.ca>
• Date: Tue, 10 Jan 2006 19:05:41 -0700

Rich, Bob,

Actually, you can simplify this quite a bit by using the area of a bolt equal to 1.00.  This give

A = N,

I = (N*r^2)/2,

c = r = radius of bolt circle

Hence

Bolt force = P/N (+-) 2*M/(r*N)

since it's more common to specify the bolt circle diameter it also becomes

Bolt force = P/N (+-) 4*M/(d*N).

Regards,

H. Daryl Richardson

----- Original Message -----
Sent: Tuesday, January 10, 2006 4:34 PM
Subject: RE: Bolt force in round column

P/A ± Mc/I

A = SUM OF BOLT AREAS

I = SUM OF MOMENT OF INERTIA OF THE BOLTS ABOUT THE CENTERLINE OF THE COLUMN PLUS THE SUM OF THE INDIVIDUAL MOMENT OF INERTIA OF THE BOLTS ABOUT THEIR OWN AXIS

c = DISTANCE FROM CENTERLINE OF COLUMN TO FARTHEST BOLT

The other terms should be obvious.

Bob Garner, S.E.

From: Rich Lewis [mailto:seaint03(--nospam--at)lewisengineering.com]
Sent: Tuesday, January 10, 2006 2:53 PM
To: seaint(--nospam--at)seaint.org
Subject: Bolt force in round column

I have a large diameter round column with bolts at about 6 inches on center around the perimeter of the base.  I know the axial load and the bending moment.  The bending moment is large.  The virtual eccentricity is larger than the column diameter so I know I have tension in some of the bolts.  Can someone direct me to a reference, or give me a formula, to calculate the maximum tension in the individual bolts?

Thanks.

Rich

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