×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

Seismic Joint vs. Structural Separation

Seismic Joint vs. Structural Separation

Seismic Joint vs. Structural Separation

(OP)
I have an addition to a large church.  To simplify the design the new portion of the structure is separated from the existing building by a 1-1/2" joint.  We have referred to this on our plans as a "Seismic Joint".  This is typical for our office.  According to the architect, by using this label the mechanical engineer has to add extensive hardware for all of his pipes/ducts that cross this joint.  However, if we refer to the joint as a "Structural Separation" these requirements do not apply.

What is the difference between these two terms?

RE: Seismic Joint vs. Structural Separation

I am confident that whatever term you use to label the joint on your plans has NO affect on how the mechanical engineer must deal with his elements crossing that joint.

You have elected to create two separate structures, each with their own lateral force resisting systems.  Each has unique performance characteristics such as their natural period, wind deflection and seismic deflection.  

You design your structure and have a maximum seismic deflection in A and also in B.  The combined deflection is the gap that you should provide between the buildings.  You also have wind deflections between the two buildings.

The mechanical engineer should be notified (by you) of what these deflections are - wind and seismic deflections will be different.

It is up to them to propoerly meet the code and detail accordingly.

 

RE: Seismic Joint vs. Structural Separation

(OP)
That is pretty much what I had assumed.  I was unaware of any difference, but figured I'd ask the question to see if there was some obscure requirement based on nomenclature.

RE: Seismic Joint vs. Structural Separation

The problem is that some plan checkers will redflag anything noted "seismic" where a "structural" note will not be redflagged. But as JAE states, both should require the same detailing.

Garth Dreger PE
AZ Phoenix area

RE: Seismic Joint vs. Structural Separation

Whatever it is, make sure the mechanical engineer has the  x,y,z max. relative deflections and rotations to be accommodated as a gas line failure across this joint would surely be detrimental to the structure.

RE: Seismic Joint vs. Structural Separation

Why not tie the two structures together and avoid the mechanical issue?

BA

RE: Seismic Joint vs. Structural Separation

Perhaps they can use flexible connections for all the pipes and ducts that will cross this joint...just a thought.

RE: Seismic Joint vs. Structural Separation

(OP)
The buildings need to be separated because the original structure is a Frankenstein's monster of various additions and renovations.  If we connect to it, we have to upgrade the original to meet the seismic requirements of the newest building code.  We definitely want to avoid that.

The mechanical engineer was fishing for a way to avoid having to use flexible connectors.  They are out of luck since we do need accommodate differential movement.

Thanks for the input.

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!


Resources