Allowable uniform loads - W beams vs. LVL

  • Thread starter yahastu
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  • #1
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I'm trying to make a comparison between the maximum allowable uniform load of a beam made of steel vs LVL.

Here is a table of allowable uniform loads for steel W beams:
https://www.engineeringtoolbox.com/w-steel-beam-uniform-load-d_1722.html

Here is a table of allowable uniform loads for LVL beams:
https://www.westfraser.com/sites/default/files/products/LVL/LVL Users Guide - US v0415.pdf

In the case of W beams, there is just 1 number for allowable load based on the span. In the case of LVLs, there is 'LL (L/360)', 'TL(L/240)', and 'BEARING.'

"To size a beam for use in a floor, it is necessary to check both live load and total load. Make sure the selected beam will work in both rows. When no live load is shown, total load will control. Spans shown are measured center-to-center of bearing."

Based on this, my understanding is that the TL(L/240) values are most comparable to the allowable load limits for the W beams.

In other words, if I'm reading this right:
A W10 x 30 beam with a 14 foot span has a maximum allowable load of 37,000 lbs, while a 1 3/4" x 11 1/4" 2.0E LVL with a 14 foot span would have a maximum Total load (L/240) of 309 lbs/LF * 14 ft = 4,326 lbs.

Please correct me if I am misunderstanding that :) Also, can anyone tell me what the "BEARING" value of 1.6/4.1 means in this case?
 
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Answers and Replies

  • #2
jrmichler
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The allowable load of a beam is the result of several calculations:
1) Maximum bending stress
2) Maximum shear stress
3) Web crippling
4) Lateral buckling
5) Flange buckling
6) Allowable deflection
7) Point loads at connections

Every one of the above is a full chapter in a book on the subject. So, while your bold face text is probably (I did not look at your links) correct, it is not complete.

Simplified tables of allowable beam loads are useable for situations where construction details are well established, such as residential house floors. Most situations require more complete calculations.
 
  • #3
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In other words, if I'm reading this right:
A W10 x 30 beam with a 14 foot span has a maximum allowable load of 37,000 lbs, while a 1 3/4" x 11 1/4" 2.0E LVL with a 14 foot span would have a maximum Total load (L/240) of 309 lbs/LF * 14 ft = 4,326 lbs.

Please correct me if I am misunderstanding that :) Also, can anyone tell me what the "BEARING" value of 1.6/4.1 means in this case?
(disclaimer,: I'm used to european building codes, so some of this stuff is new)
You should check both the total load and the live load. The live load limit is lower, because the maximal allowable deflection is lower. In general deflections are bigger with wood or lvl and this is more often the limit, where with steel the limit will tend to be the maximum bending stress or shear stress.
The bearing value of 1.6/4.1 means that you have to support the beam at the ends for 1.6 inch and in the middle for 4.1 inch. (If you use one beam for multiple spans)
 

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