×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# Calculate How Much Load A Flat Carbon Steel Bar Can Hold

## Calculate How Much Load A Flat Carbon Steel Bar Can Hold

(OP)
Can someone remind me how to calculate a load a flat bar can hold?

The material is steel. The dimensions are 1/4" X 3" X 6".

Thanks,

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

Quite a bit if it is sitting on a flat thick steel plate.

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

P*L/4 = M = f*S --> P = 4*f*S/L

L is is the distance between support points
f is the strength of the material (yield or ultimate, depending on how much deflection is allowed)
S is the section modulus = b*t^2/6

Rod Smith, P.E., The artist formerly known as HotRod10

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

Well yes, but where's the teaching moment in that?

I always go back to the only useful structural equation (I exaggerate)

In the linear range M/I=s/y=E/R

With that little thing you can build models of tapered springs, beams with any load distribution, any number of supports, and composites.

In the rather banal case you have selected, at the centre of the span M=PL/4, I is 1/12bt^3, and y is t/2

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

Beam deflections should be covered in your strength of mechanics text books (or something similarly worded). If you're an internet fan and you just want the answer:

https://www.engineersedge.com/calculators.htm

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

The question is not clear. A 1/4" x 3" x 6" flat bar can resist a tension of 3Fy/4 parallel to the 6" dimension and 3Fy/2 parallel to the 3" dimension.

BA

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

BridgeSmith,

You are assuming the bar is loaded as a cantilever.

--
JHG

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

#### Quote (drawoh)

BridgeSmith,

You are assuming the bar is loaded as a cantilever.

No, BridgeSmith is assuming the bar is loaded as a simple span with concentrated load at midspan.

BA

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

P*L/4 = M = f*S --> P = 4*f*S/L

L is is the distance between support points
f is the strength of the material (yield or ultimate, depending on how much deflection is allowed)
S is the section modulus = b*t^2/6

Hope this helps!

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

#### Quote (cole44)

P*L/4 = M = f*S --> P = 4*f*S/L

L is is the distance between support points
f is the strength of the material (yield or ultimate, depending on how much deflection is allowed)
S is the section modulus = b*t^2/6

This assumes that the OP is referring to a concentrated load at midspan of a simple span, which is not clear from his post.

If P is the applied concentrated load, then f is the allowable stress, about 0.6Fy.
If P is the factored concentrated load, then f = φFy where φ = 0.9, and S = plastic modulus = b*t^2/4.
In either case, deflection should be checked for acceptability.

Fultimate should never be used for this calculation.

BA

### RE: Calculate How Much Load A Flat Carbon Steel Bar Can Hold

Thanks, cole44 for reposting what I wrote, but did you have a comment? Btw, it's common etiquette when you quote someone to clarify that it's a quote from someone else, and not your own.

#### Quote (BAretired)

This assumes that the OP is referring to a concentrated load at midspan of a simple span, which is not clear from his post.

Agreed. I did assume the bar was in bending about its 3" width dimension, simply supported at the ends of the 6" span. There are numerous loading conditions possible. Maybe I should have followed my first inclination and not bothered to respond to this thread. It's an ill-defined question that even a second year engineering student should have no problem with.

#### Quote (BAretired)

S = plastic modulus = b*t^2/4.

If ultimate tensile strength of the material is to be used, I suppose it would be correct to use the plastic section modulus to calculate capacity. As I alluded to in my previous post, the correct stress limit and section properties to use would depend on what constitutes failure - deflection beyond a certain value, yielding, or rupture/fracture.

Rod Smith, P.E., The artist formerly known as HotRod10

#### 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.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!