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Re: Pitched Tapered Glu-Lam

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The 15 psi *is* conservative.  On the other hand, I've personally been called in
to correct an 80 foot span glulam in a school gym that had experienced a 'radial
tension failure' under dead-load only.  The original engineer hadn't checked for
radial tension.

It's often a catastrophic mode of failure since as soon as the wood splits the
section modulus is divided by 2 - if it splits only once and at mid-depth.  But,
it's usually a domino effect and the beam splits at numerous locations
throughout it's depth.   And there goes your safety factor.  It's a mode of
failure often overlooked.  And, it's an expensive thing to fix.

Lew Midlam, PE

Roger Turk wrote:

> I agree with Dick Phillips.  However, the allowable stress value of 15 psi
> for radial tension for Douglas Fir-Larch is even questionable with many
> stating that *any* radial tension for DF-L should be resisted by mechanical
> means.
> A. Roger Turk, P.E.(Structural)
> Tucson, Arizona