- There are numerous reasons why cracking can occur
on bridge decks.
Engineers must look at numerous factors
in the design process
to prevent and repair this type of damage.
The bridge design standards involving
how the concrete panels
and steel girders are configured,
play an important role in preventing cracking damage,
in what's called the Negative Moment Regions of the bridge.
A Negative Moment Region is the area
of the deck just above the interior supports
of both continuous concrete and steel girder bridges.
During a recently completed implementation project
conducted at the University of Texas,
Center For Transportation Research,
researchers worked with TxDOT to develop
and test a new design methodology.
It's designed to help the engineer
achieve the right steel content
for preventing deck cracking,
while also meeting the design requirements
for these types of bridges.
- And so we did the research to help us identify exactly
how much reinforcement we needed
in this area to help control the cracking,
and improve the durability of our concrete decks.
They implemented the knowledge they gained,
by changing the reinforcement over the vents in the slab,
on a project in Austin,
and then monitored it afterwards
and did some mud load testing
by driving dump trucks across the bridge.
- We worked with the engineer of record
to actually vary the design of the deck steel.
And the, essentially we had four different regions
that we actually were able to, to vary on that project.
So we were able to get data from that,
that specifically showed the actual performance
in a concrete bridge.
That what we were missing on that was
the behavior of what would happen in a steel bridge.
So we had a bridge of out in Bastrop,
and again working with the project monitoring committee,
we vary the reinforcing steel in that deck to again
give us very novel data on the behavior of the deck cracking
as the function of that amount of steel.
Our design methodology that was developed by George G,
who was the PhD student on this project,
really allows an engineer to get in,
and really customize their design to achieve
whatever the surface ability requirements that they're
they're actually wanting to get.
- Now that we have this information, we're gonna update
our bridge design manual,
and our details to fully implement it.
So on future projects, we're getting the right amount
of reinforcement in these negative moment regions.
- [Speaker] For more information,
and to find the publications for this project,
please visit the TxDOT research library
at the link shown below.