V4 vs. V8 GLB question
V4 vs. V8 GLB question
(OP)
I recently evaluated an existing GLB that is undersized. There are some limitations as far as reinforcement of the situation, but the easiest fix might be to add a post (it is a floor over a garage). In all likelihood since the original beam was clear span it is a V4 beam. As a two-span I would need to evaluate it as a V8. Am I correct here??
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RE: V4 vs. V8 GLB question
Also, you could drill a series of horizontal holes or cut the beam at the new post location to maintain the V4 status...
Mike McCann, PE, SE (WA)
RE: V4 vs. V8 GLB question
This made me think of a question. Why cut it at all? The cut is to relieve the negative moment at the post. Well, if we just leave it and the moment is too great, then tension fibers yield and the compressive fibers crush, decreasing the moment until the moment can be resisted.
I'm curious what people think about this. Any thoughts?
RE: V4 vs. V8 GLB question
Mike McCann, PE, SE (WA)
RE: V4 vs. V8 GLB question
That’s not bad reasoning, except... In steel, for example, which is a pretty homogeneous material, we have a pretty good control and understanding of the mechanics of this plastic hinge formation, and the moment redistribution as long as that section of the beam is prevented from bucking/rollover during the yielding process. Wood, even though in GlueLam form, is less consistent and homogeneous, so it will be (might be) a less uniform and controlled moment redistribution and yielding, ripping, whatever. I’m more concerned with the uncontrolled tensile ripping/fracture than I am with the relatively controlled crushing in compression. So, I like Mike’s idea of doing something to force/control the location of the tensile failure.
RE: V4 vs. V8 GLB question
RE: V4 vs. V8 GLB question
RE: V4 vs. V8 GLB question
Mike McCann, PE, SE (WA)
RE: V4 vs. V8 GLB question
RE: V4 vs. V8 GLB question
Mike McCann, PE, SE (WA)