Joint Detail Comparison between Bridge and Building

[JohnRwals]

Hi!

Though I sometimes read papers and articles related with bridge design,
I am not familiar with bridge industry.
I have often seen bridge construction details which do not show any specific
information about the joints.
Isn't this detail important in the bridge design and construction?
As an example, I would like to show two pictures;
these are column to foundation connection details from precast concrete bridge and building.
While precast concrete building detail shows joint width and materials (shim, grout),
bridge detail does not show anything.
Is that because this detail should be used only for design concept?
I wonder why many bridge construction drawings do not show specific info
related with joints like precast concrete column to CIP concrete.

Thanks!

JRW

 

[r13]

Look at the reinforcing detail for the two precast columns, the building column seems capable of handling gravity load only.

 

[WARose]

I'm not a precast guy, but that "Precast Concrete Building" detail is disturbing. Better hope there is only (downward) axial load with that.

 

[KootK]

Precast columns are often pure "posts" in a way that CIP columns rarely are. You basically just need some shear capacity and enough moment capacity for erection purposes.

 

[BridgeSmith]

Depending on how the design responsibilities are written in the contract, some of the connection design and detailing may be handled by the precaster, so it doesn't necessarily show up in the design drawings, but only on the shop drawings.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[blihpandgeorge]

i dont see the 2 details of being at the same 'design stage'. the bridge details appears more conceptual whereas the later detail looks like it could be a detail suitable for construction? on the bridge one is the foundation cast around the reinforcement or is there some form of grout tube? on the building detail that is a thick grout layer and the use of levelling nuts and shims seems odd. Most precast column details i see have starters coming up that sit inside a duct in the column that is grouted up.

 

[BridgeSmith]

Where we use a grout pad, we would include a similar level of detail to the one for the building column. The bridge column pictured may not require any additional detailing for the joint. Many times, there are additional instructions given in notes and special provisions.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[r13]

While precast concrete building detail shows joint width and materials (shim, grout), bridge detail does not show anything.
Is that because this detail should be used only for design concept?

I believe so. It obviously has left many details out. How you grout the rebars in the footing without grouting holes/devices.

 

[BridgeSmith]

How you grout the rebars in the footing without grouting holes/devices.

It's most likely covered in notes or a special provision, perhaps as performance-based requirements, e.g. connection must provide strength equal to or greater than the yield capacity of the bar. The method and materials are left up to the contractor.

Bridge construction in most cases is performed with an owner's representative (typically a DOT construction engineer) on site for QA during the entire construction process. For some things, like post-installed anchors and bars, the contractor proposes the materials and methods, and the owner's engineer approves it (or rejects it), in consultation with the designer, when necessary.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[JohnRwals]

When I checked some papers and DOT standard details, my impression was that bridge industry did not pay much attention to joint details.
Because I could see many details show 1/2" joint width filled with grout; this looked like filler/spacer rather than structural element.
Also, PCI bridge manual mentions minimum use of bearing pad like butt joint.

Don't you think bridge industry prefers butt joint directly connecting precast concrete members without using grout or bearing pad?

JRW

 

[r13]

This detail bothers me, how to tighten the couplers?

 

[BridgeSmith]

There are several types of mechanical couplers. Some are sleeves filled with high strength grout, while others have set screws, or even tapered wedges, to lock the bars into the coupler. If the column is precast, I would guess the bars that will be cast in the foundation are threaded into the couplers that are cast into the column.

They also may leave the type of coupler up to the contractor and precaster to work out.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[JohnRwals]

I would like to show another example from research paper of precast concrete bridge connection design.
This paper seems to show zero joint width while grout was used to fill the gap.

Is it popular practice in the bridge construction to minimize joint width in the precast concrete member joints?
(I have added common column splice detail in the precast concrete buildings inside the yellow box.
You can compare two joint details.)
What happens if 1" or 2" wide joint is used with grout in the precast concrete bridge column and pier?
My impression is bridge industry does not adopt shims and/or grout positively.

JRW