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

Reaction is smaller in Envelope Comb than that in Linear Add Comb?

Reaction is smaller in Envelope Comb than that in Linear Add Comb?

Reaction is smaller in Envelope Comb than that in Linear Add Comb?

I get reaction from dead load is 9406+1663 kN, max reaction from moving load is 846 kN. The load factor 1.2 for dead load and 1.4 for live load.
The max reaction shall be 1.2*(9406+1663)+1.4*864=14492 kN.

In CSiBrdge 23.3, the reaction from Envelope Comb is 11287 kN, while that in Linear Add Comb is 14492 kN.

According to CSiBridge user manual:


Envelope. A max/min Envelope of the defined load cases is evaluatedfor each frame output segment and object joint. The load casesthat give the maximum and minimum components are used for this combo. Therefore the load Combo holds two values for each outputsegment and joint. The Combo Type can be used for moving loads and any load case wherethe load producing the maximum or minimum force/stress is required.

RE: Reaction is smaller in Envelope Comb than that in Linear Add Comb?

I am not entirely sure I understand your question, so let me know if this doesn't explain your issue.

Envelope combination doesn't add the load cases. It simply shows the max/min value of the governing load cases at each location along the span.

RE: Reaction is smaller in Envelope Comb than that in Linear Add Comb?

I have never used CSiBrdge 23.3, but in RAPT we calculate 2 envelopes,

1 an envelope of moments with co-existing shears/reactions.
2 an envelope of shears/reactions with co-existing moments

The first gives the highest possible moments but not necessarily highest shears and reactions.

Your CSiBrdge 23.3 envelope may be the 1st one above. You would have to check with them.

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