Contact US

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!

*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

threated rod

threated rod

threated rod

How can i calculate the maximum allowed length for the 3/4" treated rod assuming a gravity load of 5 kN and the lateral load of 3kN on top of the plate.

RE: threated rod

Vertical load should be straight forward. Blodgett's Design of Weldments gives a formula for the maximum bending stress do to lateral loads for the columns. You'll also want to consider buckling.

RE: threated rod

With those loads, it's going to get complicated. Neither one creates any significant primary stresses on the bolts until the length (moment arm) gets very long (nearly 80 inches for a 50 ksi yield strength rod). However, the secondary stresses, particularly the moment due to eccentricity (deflection due to lateral load multiplied by the axial force), become substantial. Of course, as BrianE22 mentioned, the rods will be subject to substantial decreases in axial capacity due to the tendency to buckle as the slenderness increases, but the compression stresses due to the axial load are very small, so even with a high slenderness ratio, buckling may not control.

It somewhat more straightforward if you begin by choosing a length, calculating the moment and deflection due to the 3 kN lateral load, and then add the moment due to eccentricity to the primary moment and calculate the stress in the bolts. Compare that to the allowable stress to see where you're at. Then check the reduction in axial capacity due to buckling. I could point you to the buckling capacity equations from the AASHTO bridge design spec, but others can probably point you to sources will be more accessible to you.

The preceding assumes that the plate is held flat (it can move horizontally but not rotate). If it can rotate, nearly everything changes.

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.

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! Already a Member? Login


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
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’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:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close