Relationship between Beam Section Depth and Bending Moment

Click For Summary

Discussion Overview

The discussion revolves around the relationship between beam section depth and bending moment capacity, specifically comparing two universal beams of different depths. Participants explore whether the bending moment capacity can be determined without knowing the span of the beams and the implications of section depth on bending moment capacity.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that the bending moment capacity of a beam cannot be calculated without knowing the span measurement.
  • Another participant questions the understanding of the terms 'bending moment' and 'bending moment capacity', indicating that the latter is influenced by material properties and cross-sectional shape.
  • It is proposed that bending stress is roughly proportional to the square of the section depth, implying a relationship between depth and bending moment capacity.
  • A mathematical approach is suggested involving the relationship between bending moments and section properties, indicating a potential method to find the bending moment capacity of the deeper beam.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between beam depth and bending moment capacity, with no consensus reached on whether depth directly affects capacity or if other factors are more significant.

Contextual Notes

The discussion lacks specific details on the span of the beams, which is critical for determining bending moments. There are also unresolved definitions and distinctions between bending moment and bending moment capacity.

joeykeys
Messages
11
Reaction score
0
Ok. There are 2 universal beams. One is 500mm deep and the other one is 400mm deep. For both beams, the top and bottom flanges are 200mm wide x 10mm deep. [SPAN of the beams is not given]

Questions is..If the maximum bending moment capacity of the 400mm deep universal beam is 200 kn.m. What is the bending moment capacity of the 500mm deep beam?

What i think is that beam's bending moment has nothing to do with its section depth is it?
So the answer to the question would be "Cannot be calculated since both the span measurement is not given."

Or there are other answers to this?

Thanks.
 
Engineering news on Phys.org
What on Earth are you studying?
 
Bending stress is roughly proportional to the square of the section depth.
 
joeykeys said:
r
Questions is..If the maximum bending moment capacity of the 400mm deep universal beam is 200 kn.m. What is the bending moment capacity of the 500mm deep beam?

What i think is that beam's bending moment has nothing to do with its section depth is it?
Are you confusing 'bending moment' with 'bending moment capacity'? The former is a function of loading, span, end conditions, etc. while the latter is a function of the beam's material properties and cross sectional shape.
 
I'd guess is that the answer they want is something along the lines of

Sy = M1*y1/I1 = M2*y2/I2

where you know M1, y1, I1, y2, I2, and can rearrange the above to find M2.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 5 ·
Replies
5
Views
6K
Replies
3
Views
13K
  • · Replies 30 ·
2
Replies
30
Views
10K
  • · Replies 1 ·
Replies
1
Views
16K
Replies
6
Views
2K
  • · Replies 3 ·
Replies
3
Views
5K
Replies
33
Views
6K
  • · Replies 9 ·
Replies
9
Views
2K