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walkereng
walkereng, Consultant
Category: Structural Engineering
Satisfied Customers: 2730
Experience:  Over 30 years of Structural Engineering experience.
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What is a typical design unbraced Glu lam Beam?

Customer Question

what is a typical design for an unbraced Glu lam Beam?
Submitted: 1 year ago.
Category: Structural Engineering
Expert:  walkereng replied 1 year ago.
Do you have a specific application?
If you do, can you take a look at the following link and answer the questions at the bottom of the sheet? Your answers will allow me to accurately model the loading and size your beam. Thanks
https://docs.google.com/open?id=0B3LjUB_rxIbcNVlreGljdFZUZ3kxTHhvVDFnRV9uQQ
Customer: replied 1 year ago.
I have a detached garage that Im getting permitted in Phoenix,AZ. The plan reviewer wants a 'design for an unbraced beam'. The garage is 60'x50' and has 16'exterior walls. Zoning required me to reduce the roof height to 8' along the 50' side. The roof is 8' high x50' and is 8' deep. I showed a GLB with 2x6 joists spanning the 8' to the exterior wall. The GLB has a cripple wall on top of it to extend to the 16' height of the rest of the garage. The plan reviewer is referring to this beam as unbraced and wants a design to correct it.
Customer: replied 1 year ago.
The beam in question is bearing the load of the 8 ft deep shed roof framed with 2x6 joists and is holding up a nonbearing cripple wall. The trusses for the higher roof are parallel to the beam.
Customer: replied 1 year ago.
When an I expect an answer?
Expert:  walkereng replied 1 year ago.
Sorry for the delay, I had my golf league this afternoon with my son and we got home late. I am on East Coast time, so it is after midnight here.
Can you send me any drawings you may have so that I can make sure I fully understand your structure configuration?
You can attach files to the Chat Window with the paperclip in the toolbar.
I can run numbers for you with the Boise Cascade design software for LVL and Glulam beams.
Do you need calculation stamped by an engineer registered in Arizona?
Expert:  walkereng replied 1 year ago.
let me know when you come back online
Customer: replied 1 year ago.
Thanks. I will get you the info. It may not be until tomorrow.
Expert:  walkereng replied 1 year ago.
That is fine.
Talk to you tomorrow.
Customer: replied 1 year ago.
This is a pic of the plan. The glb that's unbraced is per detail A/3. Let me know if you need additional info.
Customer: replied 1 year ago.
Did you receive my email attachment an are there any questions?
Expert:  walkereng replied 1 year ago.
I did, I will take a look at it this morning when I get into my office.
Expert:  walkereng replied 1 year ago.
I have a few more questions:
1. So there are 4 Glue Lam Beams, that each span 15'?
2. You have 2x6 roof rafters that frame into one side of the GLB and attach near the bottom of the beam at it's bottom? What is the span of the 2x6's?
3. The 2x6 wall framed in on top of the GLB is 8' high for the full length? So this wall on top of the beam is a gable end wall, with no roof load, just wall Dead Load?
Expert:  walkereng replied 1 year ago.
Let me know when you come back online
Customer: replied 1 year ago.
1. Yes
2. Yes. 8'
3.Yes
Expert:  walkereng replied 1 year ago.
I’d like to point out that a Professional Engineer’s standard of care typically includes a site visit to assess field conditions and get an overall understanding of the structure. This can obviously not be accomplished through the internet. The information provided here is meant for planning purposes only (general sizing and budgeting) and is based on the information provided by you. All loading cases considered are for vertical loads only, no lateral analysis has been completed. The information should be verified by a professional engineer who can visit the site to ensure that potentially important information has not been overlooked or omitted.
I can give you a Glulam Beam option for your 15’ span roof beam:
5-1/8” x 9” Boise Glulam 24F-V4/DF
This is a Boise Cascade product and you can go to the following link to find distributors in your area. http://www.bc.com/wood/ewp/distributors.html
You will need to have a local engineer detail your connections, size your support columns and determine foundation requirements.
Here is a weblink to a computer printout of the design that has an unbraced length of 14.5'
https://drive.google.com/open?id=0B3LjUB_rxIbcbnR1RHdqTnh5eUU
This beam is considerably smaller than the one you have specified in your plans. The tributary load from the 8' span roof rafters off the right side of the beam, is a 4' tributary width with a roof Live Load of 20 psf and a roof Dead Load of 15 psf. The 8' tall cripple wall on top of the beam, I assume a Dead Load of 20 plf. Since the roof trusses run parallel to these beams, I assumed no more roof load is supported by these beams.
If you feel you have received a satisfactory answer to your question, click the Rating button that is appropriate. Experts are credited for each adequately Rated answer they provide. If you have additional questions, please let me know. Thanks
Expert:  walkereng replied 1 year ago.
If you feel you have received a satisfactory answer to your question, click the Rating button that is appropriate. Experts are credited for each adequately Rated answer they provide. If you have additional questions, please let me know. Thanks
Expert:  walkereng replied 1 year ago.
Let me know if you have any more questions and we can wrap things up.

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