(calm jingle)
- [Announcer] Current bridge design specifications published
by the American Association
of State Highway Transportation Officials employed a load
and resistance factor design methodology.
The specifications are used in the design,
evaluation, and rehabilitation of bridges.
A recently completed TxDOT research project conducted
at the University of Texas at Austin's Center
for Transportation Research has filled in
some knowledge gaps in the spec through laboratory testing
and proposed design recommendations for a special class
of CTT nodes used in strut-and-tie modeling.
- And bridge substructure is basically below
what's the deck of a bridge.
And in those disturbed regions, particular care is needed
in designing and detailing bridge components.
Over the years, research sponsored
by Texas Department of Transportation answer the series
of questions that help simplify designs
and ease the construction of such components,
but then not all questions were answered.
Open questions that were left got answered during the course
of this research project.
And those questions relate to how to better detail
the bridge foundations, how to better detail the column
to cap connections, so these are the vertical components
that we have below the bridge deck.
And as they tie into the horizontal components,
that then support beams that provide support
to the bridge deck proper.
- With all the past research done in strut-and-tie,
we found that there were a couple of items
that hadn't been fully fleshed out.
This project has provided us with the knowledge
to help us fine-tune the design of our bridge elements.
- For example, we do have code limitations
on what's called a crack control reinforcement,
so reinforced concrete components are expected to crack
under service loads, but having to manage those cracks,
number of cracks, widths of those cracks, and so on
is done through the crack control reinforcement.
The code limitations on the spacing of that reinforcement
was done on the basis of scaled laboratory specimens.
And we were able to basically push the boundaries
and test at a scale that allowed us
to relax the code provisions based on experimental findings
without compromising the service or ultimate behavior
of those bridge substructure components.
So what does that mean?
Simpler bridge details and savings associated
with those simpler details in constructing bridges.
So that's how the research project contributed
to the overall design and construction
on bridges within the state of Texas.
And what we have done here is refine the understanding
on bridge component behavior, therefore,
the design provisions that go with it to where savings
can be accomplished in structural details,
simplicity can be leveraged in bridge construction,
and therefore, savings are possible
in serviceable structures that are designed
by bridge design professionals in the state.
- We are always trying to improve the products we provide
to the traveling public.
And one of the benefits of this research is we're able
to reduce construction costs on some elements
and also improve reliability of other elements
so that it's a more reliable, safer,
and hopefully more cost-effective bridge.
- [Announcer] For more information
and to find the publication for this project,
please visit the TxDOT research library
at the link shown below.