×
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.

# ASCE 41-17 - Force Controlled Action

## ASCE 41-17 - Force Controlled Action

(OP)
I am a little lost in understanding the intent of equation 7-35 of ASCE 41.

From my understanding of ASCE 41 (I have limited experience in this document), force controlled action in an element should be capable of resisting that maximum force that can be delivered to them (think seismic steel design etc) with the intent of remaining elastic.

Option (1) of 7.5.2.1.2 for determining the force to a force controlled element is worded in such a way that makes sense to me:
"the force shall be taken as the maximum action that can be developed..."

Part 2 (as snipped above above) feels odd to me. After running my calculations, I have the following factors for option 2 of the force controlled demand:
χ = 1.0
C1 = 1.79
C2 = 1.14
J = 2.0

Because C1 * C2 * J ~= 4.1 I essentially can divide my seismic force by a factor 4.1? Something feels off for an element that should be designed to remained elastic

I am checking the shear resistance of a concrete shear wall, where I have determined that I want my inelasticity to be from flexural yielding and I want my shear capacity to be able to develop the flexural yield capacity of the conrete wall.

If I run my calcs via option one I fail miserably in shear. I determine my shear demand by taking my flexural capacity and dividing by half the height of the building. This feels more in line with traditional force controlled ideology

If I run my calcs via option of of 7.5.2.1.2 I pass wonderfully

Something feels fishy in option 2, I would at least somewhat close results between the two differing setups. Maybe I miss calc'd something somewhere.

Appreciate thoughts on the topic!

S&T

### RE: ASCE 41-17 - Force Controlled Action

Take a look at the additional commentary and examples in this document (Link) and let us know if you still have questions.

### RE: ASCE 41-17 - Force Controlled Action

Force-controlled elements don't have to be capacity designed - they only need to be designed to stay linear while seeing "real" loads.

Option 1, which is the capacity design option, is there to set an upper-bound on the "real" load the force-controlled element can see. If the force-controlled element works for a capacity design, then you can stop there.

Option 2 is based on calculating the "real" force. The force in your analysis isn't your "real" force because your analysis keeps everything linear, but in real life, some elements will go nonlinear. The C1C2J factor is there to reduce your overestimated linear forces back down to "real" forces.

#### 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!