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RE: Ridge beam/joist analysis

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You analysis appears to be correct.  Because the load is at an angle to the
joist, you will have a "bending" component and an "axial" component to the
load.

The easiest way to handle it is to tie the joist to the one on the opposite
slope.  Use a strap (Simpson or other) across the top of the joists, or a
bolt through the ridge beam.  The result will be an equal-and-opposite
tension force at the ridge, tension in the member, and no horizontal
reaction at the top of the wall.

---
Jason Kilgore
Leigh & O'Kane, LLC
Kansas City, Missouri

> -----Original Message-----
> From: Craig & April [mailto:csmleko(--nospam--at)bellsouth.net]
> Sent: Sunday, June 27, 2004 4:42 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Ridge beam/joist analysis
> 
> Any thoughts on the conventional knowledge(?) that a structural ridge beam
> eliminates all lateral thrust at the exterior joist bearing walls? I'm
> designing a timber camp roof with a 10:12 pitch. Looking at the joist
> member
> as it will exist in the structure, (i.e. pitched) the loads are obviously
> vertical at beam and wall. However, in order to do an exact analylsis of
> the
> joist, I applied the 'w' load (reduced for actual longer span) at the
> appropriate angle to a horizontal joist. An axial load exists as the
> result
> of the partial vector. This seems to indicate tension in the joist (if
> supported from beam) or compression (if supported at walls)...which is
> contrary to what I thought I knew. Anyhow, I hope I'm wrong because
> developing the lateral restraint would be tough at 8x8 timber walls...
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