(soft music)
- [Narrator] In the construction of composite steel bridges,
shear studs are used
to connect the concrete bridge deck to the steel girders.
A large number of these shear studs are needed
to meet AASHTO strength and fatigue requirements.
Researchers at the Center for Transportation Research
at the University of Texas at Austin
have explored the use of larger diameter shear studs,
which can speed up the construction process
and improve worker safety.
- This project is really looking at the feasibility
of using larger diameter shear studs.
And with that, a lot of things happen.
When you can use the larger diameter shear studs,
there's less shear studs,
so it improves worker safety.
It can expedite the girder fabrication process.
And then it also,
it facilitates the use
of our partial-depth precast deck panels,
which we call PCPs.
The use of PCPs for deck construction
act as the formwork for the bridge deck.
They speed up construction
and they serve as a safe working platform
for the workers.
- We had quite an extensive laboratory program.
It was a long project, nearly four years,
and a lot of work in the laboratory.
Much of that was learning
how to weld these larger diameter shear studs.
They have to be welded to the top of a steel girder
in the construction process.
And there we had a lot of help from industry.
So we had a very collaborative project
working closely together,
you know, our research team working
with TxDOT engineers and with industry.
Our work was done at,
it's the University of Texas Ferguson
Structural Engineering Laboratory,
which is at the University of Texas Pickle Research Campus
in northwest Austin,
where we're testing bridge components
generally to failure
either under fatigue loading
or ultimate strength type loading.
- [Jamie] Push-out tests on studs at Ferguson Laboratory
were conducted to evaluate
the static and fatigue performance
of the 1 1/8th-inch diameter studs.
The results of those static push-out tests
showed excellent performance.
- We also constructed two bridge girders in the laboratory
that were quite large.
Each one was a hundred foot long.
Where we could essentially do a proof of concept
to show that these larger diameter shear studs
will in fact work successfully in an actual bridge girder.
- So this project is definitely ready to implement.
The project included design recommendations.
Therefore, future steel bridges can be designed
with larger diameter shear studs.
This research will serve a national purpose as well,
because what bridge engineers used to design bridges
was missing ways to design
these larger diameter shear studs.
And so this project will fill a hole
that bridge engineers can use all over the U.S.,
not just Texas.
- [Narrator] For more information
and to find the publications for this project,
please visit the TxDOT Research Library
at the link shown below.