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Re: Glulam Beam Retrofit

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I like Christopher's response.  I just did a glu-lam beam retrofit for a pizza place roof.  The primary reason for the beam failing was ponding.  There was nearly 6 inches of standing water to either side of the beam.  The problem was amplified by additional equipment installed by the pizza place without proper engineering or permit.  Once the ponding was mitigated and the equipment removed we were left with a glu-lam beam that on the whole calculated out, but now had a long horizontal crack near the middle.  I simply calculated the amount of shear flow transfer we needed, had them jack up the beam and then installed all-thread rods vertically through the beam with malleable washers each side.  I mapped out a varied spacing depending on distance to the support.  The calculations showed the beam (originally sagging more than 3 inches) should deflect about 1/2 inch under dead load, and amazingly it did exactly that once the shoring was removed.  It's really nice when the numbers actually reflect reality that closely.
 
Mark Pemberton, S.E.
Pemberton Engineering
Davis, CA

Christopher Wright <chrisw(--nospam--at)skypoint.com> wrote:

On Dec 15, 2004, at 3:38 AM, Eknrinc(--nospam--at)aol.com wrote:

> I have a glulam beam overstressed in flexure. Anyone have any great
> retrofit ideas?
I know almost nothing about glu-lam, but I do know some things about
fixing overstress. The sequence is everything: find the source of the
overload and fix that; then fix the beam. Nothing 'just breaks,' no
matter what the laity says. If you don't find the reason, you don't
know if you're actually fixing the problem.


Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com | this distance" (last words of Gen.
...................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw/


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