In addition to the other responses you have already received on this issue,
don't forget that the addition of the center post under the continuous GLB
causes the maximum moment to be a negative moment located at the new post.
This means that the top of the GLB is in tension now, not the bottom. For a
standard 24F-V4 GLB, the tension capacity of the top in bending is half that
of the bottom, so plan accordingly in your design.
Two other retrofit ideas. 1) Replace the beam with a new PSL. 2) Add a
steel plate on each side of the beam (flitch plate) and bolt through the
Bruce Resnick, SE
Parker Resnick Str. Eng.
In a message dated 6/29/99 10:36:53 PM Pacific Daylight Time,
<< One of my clients wishes to install a garage door to his two car garage.
The header beam is too low and needs to be reduced in depth by about 4.5
inches. One of the solutions proposed by the client's contractor is to
remove the bottom three laminations and add a new post + pad about
mid-span. The current Glulam beam is 21 inches deep. It works as a 16.5
inch beam for the reduced span.
Question: Is there a problem if he cuts 4.5 inches from the bottom of the