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(calm jingle)

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- [Announcer] Current bridge
design specifications published

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by the American Association

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of State Highway Transportation
Officials employed a load

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and resistance factor design methodology.

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The specifications are used in the design,

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evaluation, and rehabilitation of bridges.

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A recently completed TxDOT
research project conducted

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at the University of
Texas at Austin's Center

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for Transportation Research has filled in

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some knowledge gaps in the
spec through laboratory testing

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and proposed design
recommendations for a special class

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of CTT nodes used in
strut-and-tie modeling.

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- And bridge substructure
is basically below

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what's the deck of a bridge.

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And in those disturbed regions,
particular care is needed

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in designing and detailing
bridge components.

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Over the years, research sponsored

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by Texas Department of
Transportation answer the series

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of questions that help simplify designs

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and ease the construction
of such components,

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but then not all questions were answered.

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Open questions that were left
got answered during the course

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of this research project.

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And those questions relate
to how to better detail

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the bridge foundations, how
to better detail the column

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to cap connections, so these
are the vertical components

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that we have below the bridge deck.

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And as they tie into the
horizontal components,

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that then support beams
that provide support

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to the bridge deck proper.

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- With all the past research
done in strut-and-tie,

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we found that there were a couple of items

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that hadn't been fully fleshed out.

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This project has provided
us with the knowledge

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to help us fine-tune the
design of our bridge elements.

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- For example, we do have code limitations

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on what's called a crack
control reinforcement,

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so reinforced concrete
components are expected to crack

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under service loads, but
having to manage those cracks,

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number of cracks, widths
of those cracks, and so on

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is done through the crack
control reinforcement.

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The code limitations on the
spacing of that reinforcement

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was done on the basis of
scaled laboratory specimens.

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And we were able to
basically push the boundaries

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and test at a scale that allowed us

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to relax the code provisions
based on experimental findings

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without compromising the
service or ultimate behavior

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of those bridge substructure components.

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So what does that mean?

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Simpler bridge details
and savings associated

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with those simpler details
in constructing bridges.

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So that's how the research
project contributed

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to the overall design and construction

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on bridges within the state of Texas.

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And what we have done here
is refine the understanding

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on bridge component behavior, therefore,

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the design provisions that
go with it to where savings

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can be accomplished in structural details,

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simplicity can be leveraged
in bridge construction,

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and therefore, savings are possible

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in serviceable structures
that are designed

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by bridge design
professionals in the state.

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- We are always trying to
improve the products we provide

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to the traveling public.

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And one of the benefits of
this research is we're able

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to reduce construction
costs on some elements

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and also improve reliability
of other elements

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so that it's a more reliable, safer,

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and hopefully more cost-effective bridge.

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- [Announcer] For more information

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and to find the publication
for this project,

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please visit the TxDOT research library

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at the link shown below.