| Page 2 of 2 | 1 | 2 |
|
|
Rob-
I thought I was being too conservative but I feel a lot better using 1.4 E06 for sawn DF. The problem you describe with LVL is very upsetting; I thought the engineered wood products were more consistent & could be trusted to perform as calc'd. Good to know actual perfomance is otherwise cheers Bob |
Bob Morrison wrote:
In a previous post Rob Munach says... Typically, in my designs, I won't even come close to code allowed deflections. It doesn't cost much to go up 2" or 4" on an LVL, but you get a significantly stiffer beam and no call backs. And particularly important when the beam is a window or door header! Yup. alot of contractors around here use the suppliers to size their LVL's for free. They typically use just above code required deflections .. The contractor gets what he *paid* for. I had a contractor ask me recently for a design to resist a 5000lb uplift at the end of an LVL. I couldn't imagine where that was coming from until I saw the beam design from the supplier. It turns out, it was a 2 span beam with one of the spans being really short. Since the supplier modeled it as 3 pinned bearings instead of 2 pinned bearings and a cantilever, he ended up with a huge uplift at the short end! -- Rob Munach, PE Excel Engineering PO Box 1264 Carrboro, NC 27510 |
Chuck wrote:
"Rob Munach" wrote in message ... Bob Morrison wrote: In a previous post Rob Munach says... Typically, in my designs, I won't even come close to code allowed deflections. It doesn't cost much to go up 2" or 4" on an LVL, but you get a significantly stiffer beam and no call backs. And particularly important when the beam is a window or door header! Yup. alot of contractors around here use the suppliers to size their LVL's for free. They typically use just above code required deflections . The contractor gets what he *paid* for. I had a contractor ask me recently for a design to resist a 5000lb uplift at the end of an LVL. I couldn't imagine where that was coming from until I saw the beam design from the supplier. It turns out, it was a 2 span beam with one of the spans being really short. Since the supplier modeled it as 3 pinned bearings instead of 2 pinned bearings and a cantilever, he ended up with a huge uplift at the short end! Rob; Why would you model it as a cantilever it won't behave that way. It will still be connected to the end column of the short span will it not? once connected it will feel the uplift. Chuck, The beam will only be toenailed to the stud column which will easily be overcome by about 100lbs.(at least in residential construction in our area) If it had an uplift connection to the column and the column was bolted to the foundation, then you would be correct. Adding this third pinned bearing also decreased the size of his beam due to the span continuity (hence the large uplift - there ain't no free lunch). I guess I should have said if he was intent on making this beam one piece, he should have modeled it with a cantilever (and checked the upward tip deflection for potential serviceability problems). I would have modeled it as two separate beams in this case. Regards, Rob The only way it can behave like a cantilever is if the column fails or is not used. The worst case is if the longer span is loaded and the short span is not then the short span will not only have a large uplift reaction but will have negative moment / tension on the top and deflect upwards. The only way a cantilever will work is if the end column isn't there. Is this what you are referring too? Chuck... __________________________________________________ _____ Charles I. Dinsmore, PE SE RA ~ -- Rob Munach, PE Excel Engineering PO Box 1264 Carrboro, NC 27510 |
In a previous post Rob Munach says...
It turns out, it was a 2 span beam with one of the spans being really short. Since the supplier modeled it as 3 pinned bearings instead of 2 pinned bearings and a cantilever, he ended up with a huge uplift at the short end! I usually have the contractor cut the top 1/3 of the beam (or through the top flange of I-joist) at the middle support. This makes two non- continuous spans, but one piece of lumber. -- Bob Morrison, PE, SE R L Morrison Engineering Co Structural & Civil Engineering Poulsbo WA |
Bob Morrison wrote:
In a previous post Rob Munach says... It turns out, it was a 2 span beam with one of the spans being really short. Since the supplier modeled it as 3 pinned bearings instead of 2 pinned bearings and a cantilever, he ended up with a huge uplift at the short end! I usually have the contractor cut the top 1/3 of the beam (or through the top flange of I-joist) at the middle support. This makes two non- continuous spans, but one piece of lumber. Good idea. -- Rob Munach, PE Excel Engineering PO Box 1264 Carrboro, NC 27510 |
Guys,
It's sounds like I've sparked quite a debate with my original question. I truely appreciate all the help. I ended up having an engineer come out and we determined that the wall was NOT load bearing. No beam needed. The cost of the engineer ended up costing me more than the price of putting up a beam - doh! Thanks Again, Matt |
In a previous post says...
It's sounds like I've sparked quite a debate with my original question. I truely appreciate all the help. I ended up having an engineer come out and we determined that the wall was NOT load bearing. No beam needed. The cost of the engineer ended up costing me more than the price of putting up a beam - doh! Yeah, but just think of how much better you will sleep at night! -- Bob Morrison, PE, SE R L Morrison Engineering Co Structural & Civil Engineering Poulsbo WA |
| All times are GMT +1. The time now is 11:40 PM. |
|
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter