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

RAM CONCEPT - One way slab and beam system

RAM CONCEPT - One way slab and beam system

RAM CONCEPT - One way slab and beam system

I am modeling a podium slab as a one-way slab and beam system. When modeling the slabs and beams i have some questions about the design strip options.

1. for the one way slabs, When defining the strip, should the width be per the "code slab" option, which gives column and middle strips, or should i use the full width option?
2. For the beams in the longitudinal direction, should I check the the box "Design column strip for column + middle strip resultants"? If i leave this unchecked, i am getting shear failures in the middle strip portion of the beam, but when i look at the cross section, it shows that my shear capacity is zero. It seems like this box should be checked.
3. For the beams, I have the cross section set to trim to T or L. For the middle strip, does this need to be set to 2-way slab? I have seen the tech note from Bentley, and this appears to be the case.


RE: RAM CONCEPT - One way slab and beam system

Hi Strguy11,

1. Have you modeled the slabs as 'two way' or 'one way' (Mesh Input > Object Properties). Generally speaking, all slabs are inherently 'two way' yet will behave closer to one way slabs as the aspect ratio increases. I believe the 'code slab' design strip option is for typical two way slab systems and isn't applicable to your case. I'd select 'full width' strips and break them up along the length of the beams to capture the different moment fields present (ie centre a strip spanning between the mid-span of the beams, usually this region will have the highest hogging/sagging moments).

2. For the structural arrangement you have described, I'd stick with designing the column strip (beam + effective flanges) both MS/CS resultants. This is essentially the basis for pure one way design. Read this wiki for further info. http://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/4507.ram-concept-design-strips-tn

3. Correct. Selecting cross section trimming 'none' will usual achieve the same thing.

RE: RAM CONCEPT - One way slab and beam system


for the slab, i set it to one way. I was thinking of doing this with multiple design strips to try to not average the forces over wide strips... So these should be two way?

Also, what are your thoughts between the beams, parallel to the beams? Would you model intermediate strips between the beams if they are far apart... say 35 feet on center??

RE: RAM CONCEPT - One way slab and beam system

Keep your slab behavior as 'one way'. That's fine. What are the aspect ratios of the slab bay between the beams?

If the slabs are modelled as purely 'one way' it doesn't really matter how wide your slab design strip is... because all design actions are going in the same direction. But... to double check I suggest breaking up the slab design strips along the length and verifying this. Perhaps take 1m wide strips.

Slab strips parallel to the beam (ie secondary direction) will have no design actions passing through them as you've modeled a pure 'one way' system. In this circumstance, the slab will be designed for minimum reo or crack control clauses.

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