×
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!

*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

Integral bridge deck pour sequence explanation

Integral bridge deck pour sequence explanation

Integral bridge deck pour sequence explanation

(OP)
Hi there,

I have been involved with the design of a integral bridge structure that comprises a main steel box girder with a composite deck supporting the carriageway. I am trying to better understand the proposed deck pour sequence.

The pour sequence splits the integral diaphragm pours from the deck pour. Is there a reason this is done separately instead of pouring the integral diaphragm and pier deck at the same time e.g. P1 deck and diaphragm together? See attached image.

I guess another general question would be, why are positive moments commonly poured separately to the negative moments? Is this strictly to reduce shrinkage cracks or are there other reasons? If so what would they be?

RE: Integral bridge deck pour sequence explanation

There was probably a concern that the change in cross section from the diaphragm to deck would lead to transvers cracks in the deck, if it were done monolithically.

Positive moment areas are typically poured first. If the negative area is placed first there's a chance it could crack when the positive area deflects. A continuous bridge deck can be placed in one continuous operation if the volume isn't too large (< 360 CY) and set retarders are used.

RE: Integral bridge deck pour sequence explanation

(OP)
Thanks bridgebuster, what you wrote is very helpful. Do know of any sources that would go a bit further into the theory of the cause of transverse cracking in the deck for monolithic pours with the integral diaphragm?

RE: Integral bridge deck pour sequence explanation

RStars- I’ll look through my files; might have something. The diaphragm and the slab will shrink (drying shrinkage) at different rates. In a way, the diaphragm would act as a restraint for the slab.

RE: Integral bridge deck pour sequence explanation

(OP)
Thanks bridgebuster, very helpful.

RE: Integral bridge deck pour sequence explanation

you're welcome

RE: Integral bridge deck pour sequence explanation

The attached photos show another good reason to properly sequence bridge deck construction AND demolition. The photos show how the bridge beams lifted up off their abutment bearing seats because the deck was removed in an incorrect sequence. The continuous 3 span bridge had hinged beam splices just inside the middle span. The first span lifted as the middle span (over the highway) dropped due to the weight of an excavator using a slab crab to remove deck sections.

www.PeirceEngineering.com



RE: Integral bridge deck pour sequence explanation

Looks like a fairly large skew, which compounds the problem of, placing or removing a deck. Where was this PEinc?

RE: Integral bridge deck pour sequence explanation

It is just outside Philadelphia. The bridge had those now-banned pin hanger connections. As the excavator removed deck sections and moved from span 1 to span 2, it passed the hinge point and the deckless beams for the first span pivoted about the pier. The pinned ends of the first and second span beams dropped as the abutment end of the deckless beams rose up off the rocker bearings. That's when they called me.

www.PeirceEngineering.com

RE: Integral bridge deck pour sequence explanation

thanks PE

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

eBook - The Future of Product Development is Here
Looking to make the design and manufacturing of your products more agile? For engineering and manufacturing organizations, the need for digital transformation of product development processes just became more urgent than ever so we wanted to share an eBook that will help you build a practical roadmap for your journey. 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