×
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.

Fb the bending stress allowed

Fb the bending stress allowed

(OP)
Looking at Appendix 5-67 in the AISC Manual of Steel Constuction formula (5):
Fb=12,000,000/(ld/Af) is less than or equal to 22,000psi
l is length, d is beam depth, Af is area of the compression flange.  When I use this to evaluate truss loads availible for the installation of hoists, I end up with monster beams required for everything.  Can any one point me in the right direction?  Thanks.

RE: Fb the bending stress allowed

bumpjones:
What edition of AISC are you looking at?

(OP)
The sixth.

RE: Fb the bending stress allowed

Wheee...that's a bit old.  Current ASD is the 9th edition.

If you're working with trusses, and applying new loads to them (from your hoists) the Fb is primarily intended for bending stress, not a typical axial stress found in truss members.  This, of course, is assuming you are attaching the new loads to the truss at the truss panel points.

Could you describe your situation a bit more?  Normally, on an existing truss, we would avoid attaching between truss panel points, thereby avoiding bending in the truss members.  That way, the truss members only take axial loads.

You would then use Fa allowable stresses instead of Fb.

RE: Fb the bending stress allowed

to my opinion, the best way is to have bracings in the plane of the lower chords between the loaded truss and one of the adjacent trusses

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!