×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Cantilever Tendon Transition btwn. Segments of a Box Girder (Balanced Segmental Bridge Construction)

Cantilever Tendon Transition btwn. Segments of a Box Girder (Balanced Segmental Bridge Construction)

Cantilever Tendon Transition btwn. Segments of a Box Girder (Balanced Segmental Bridge Construction)

(OP)
HI,

I have a question regarding the transition of cantilever strands (usually at the top of web) for box girder bridges. Attached are two pictures of the cross section of the box girder showing the cantilever tendon ducts (usually already cast in place), and another picture showing the plan of the cantilever tendons during construction (balanced cantilever).

How does one ensure that the cantilever strands are able to transition from one duct (say duct number 8) to another without causing alignment issues, or the strands getting pinched (since the segments are flush), or ensuring the strands are grouted well at the transition location? Are there duct couplers of some sort? I am currently trying to understand this issue since I will be working on a project pretty soon.



RE: Cantilever Tendon Transition btwn. Segments of a Box Girder (Balanced Segmental Bridge Construction)

This question really is general for any type of segmentally constructed post tension style bridge or even spliced post tension construction. These have what are called match-cast ends. The concrete fits together absolutely perfectly due to these match-cast indentations that have been cast to the ends of the concrete. Before they are mated together, they typically coat the surfaces with an epoxy adhesive. The ducts will have matchcast couplers and boots with gaskets to keep the joint water tight. At the CIP sections, the ducts get coupled and extended across. Ensuring the coupled duct is sealed and watertight is something that we are always getting on the Contractor's case about. The last thing you want is the juice from the CIP pour to leak into a pourly sealed duct and then you have issues fishing your PT tendons through.

This type of construction is pretty precise and everything is laid out accurately before it is precast. A quality precaster is important.

There is a lot of information out there for you to read on these subjects. I suggest you inform yourself on all aspects of segmental construction. Perhaps if your superiors see your thirst for knowledge, they will entrust some of the meatier portions of the design to you. Lucky you for getting to work on a segmental bridge construction design.

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


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
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