×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

glulam definitions

glulam definitions

glulam definitions

(OP)
Where can one find the various grades of glulam's and their definitions such as this attached definition.

With the Southern Pine you could use 26F-V4 material with 2600 Fb. top and bottom.

RE: glulam definitions

Pick up the NDS.

It will contain all the relevant definitions.

26F, or 28F- is always the nominal bending stress in hundreds of psi..

I believe the V1, V2..  refers to the grade of veneer (how good it looks)..  

RE: glulam definitions

AITC 117-2004 is a recommended reference for designers, building officials, laminated timber manufacturers, and quality assurance agencies. free download

https://www.aitc-glulam.org/shopcart/index.asp

 

RE: glulam definitions

(OP)
thanks everyone. i guess i need study glulams a little.

RE: glulam definitions

Go to the American Institite of Timber Construction (AITC) for this type of information: www.aitc-glulam.org

RE: glulam definitions

The 26F refers to the allowable bending stress at the "bottom" face of the beam.  The V4 or similar is the combination symbol and is critical to your specification.  

"V" indicates Visual grade for strength and has nothing to do with the architectural appearance of the beam.

Architectural appearance is determined by the following terms and has nothing to do with strength: "industrial appearance, architectural appearance, premium appearance"

A glued laminated beam consists of multiple laminations, each of which, consistent with its final manufactured location in the glulam section, experiences a different load demand upon it.  for example, only the outermost lamination on the bottom face of the beam will experience the demand of the 'extreme fiber in tension' under bending loads.  The lamination at the neutral axis will not experience that load demand, and therefore need not be capable of resisting the same load as the outermost lamination.  the glued laminated industry has defined the strength of the laminations at each place throughout the depth of the beam so that the design values exhibited in the codes are truly there.  The location and load capacities of each of these laminations must be combined in an exact order in order to insure the design capacities for the complete glulam section.  Hence the term "combination symbol".   

For example, a 24F-V4 DF/DF and a 24F-V8 DF/DF both provide for 2400 psi extreme fiber in bending tension at the bottom face of the beam.  But the V4 is intended for a simple span beam and consequently provides only 1200 psi extreme fiber in bending tension at the top face of the beam.  So, should the beam be installed upside down, or should the beam be used in a cantilevered condition, the maximum bending will not be 2400 psi but 1200 psi.  

The V8 combination is intended for a cantilevered condition and therefore the 2400 psi extreme fiber in bending is available at both faces.

Consequently, one can see also, a notch in the bottom face of such a beam is even more critical.  Not only is the depth of the beam reduced, but the allowable extreme fiber in tension may well be reduce too, depending how deeply the notch extends into the laminations.   

RE: glulam definitions

Note that the "bottom" is the tension face whether it is on the top or bottom.  

It is possible to use a 24FV4 in lieu of a V8 for a cantilever if you mount it upside down, and the tension face of the back span does not exceed 1200 psi.  This is assuming the cantilever mopment is greeater than twice the backspan moment.

Contrarily, it is also possible to ues the same member with a 24FV4 rightside up if the cantilever moment is less than half of the backspan moment.  

You just have to play the numbers game.

 

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources