1
00:00:00,568 --> 00:00:01,401
(soft music)

2
00:00:01,401 --> 00:00:04,068
(air wooshing)

3
00:00:09,300 --> 00:00:11,100
- [Announcer] Deck
haunches are commonly used

4
00:00:11,100 --> 00:00:12,840
on both prestress concrete

5
00:00:12,840 --> 00:00:15,450
and structural steel girder bridges.

6
00:00:15,450 --> 00:00:18,690
The haunch is the area between
the top of a bridge girder

7
00:00:18,690 --> 00:00:20,880
and the bottom of the concrete deck

8
00:00:20,880 --> 00:00:23,910
that helps maintain a
uniform deck thickness.

9
00:00:23,910 --> 00:00:25,500
A recently completed Center

10
00:00:25,500 --> 00:00:27,570
for Transportation research project

11
00:00:27,570 --> 00:00:29,880
conducted full scale laboratory testing

12
00:00:29,880 --> 00:00:32,100
and developed computational models

13
00:00:32,100 --> 00:00:34,140
on a wide range of haunch details

14
00:00:34,140 --> 00:00:35,850
for both pre-stressed concrete

15
00:00:35,850 --> 00:00:38,580
and structural steel girder bridges.

16
00:00:38,580 --> 00:00:41,130
This work has resulted in
guidelines for analyzing,

17
00:00:41,130 --> 00:00:44,430
designing and detailing haunches,
having different heights

18
00:00:44,430 --> 00:00:47,340
and reinforcement detailing,
improving the effectiveness

19
00:00:47,340 --> 00:00:49,863
of current TxDOT detailing practices.

20
00:00:50,880 --> 00:00:55,650
- The haunch is necessary
to help keep the deck

21
00:00:55,650 --> 00:00:58,640
and the beams acting together.

22
00:00:58,640 --> 00:01:00,990
And so this research was all

23
00:01:00,990 --> 00:01:05,250
about how we reinforce
that haunch area to make it

24
00:01:05,250 --> 00:01:07,500
so it all works together.

25
00:01:07,500 --> 00:01:11,250
- The haunch is actually
the connection, you know,

26
00:01:11,250 --> 00:01:13,980
generally it's the region
over the top flange or the top

27
00:01:13,980 --> 00:01:18,180
of the girder to where it
connects to the concrete slab.

28
00:01:18,180 --> 00:01:20,640
And a lot of times we'll end up

29
00:01:20,640 --> 00:01:22,950
having maybe an eight
inch thick concrete slab

30
00:01:22,950 --> 00:01:25,260
that we use for the bridge deck, but then

31
00:01:25,260 --> 00:01:29,310
due to changes in geometry of
the girders along the length,

32
00:01:29,310 --> 00:01:31,500
a differential camber
between adjacent girders.

33
00:01:31,500 --> 00:01:33,960
A lot of times there'll be a
a little bit thicker region

34
00:01:33,960 --> 00:01:36,150
over the top of the girders.

35
00:01:36,150 --> 00:01:38,490
Most standard haunches

36
00:01:38,490 --> 00:01:41,700
in both steel and concrete
bridges are usually

37
00:01:41,700 --> 00:01:45,570
at the order of maybe
zero to three inches.

38
00:01:45,570 --> 00:01:48,750
In some cases where there might
be an extreme geometry issue

39
00:01:48,750 --> 00:01:51,360
with the bridge, some cross
slope issues across the width

40
00:01:51,360 --> 00:01:54,900
of the bridge, they may need
to have a thicker haunch.

41
00:01:54,900 --> 00:01:57,570
Some cases there'll be
construction problems

42
00:01:57,570 --> 00:02:01,110
that lead to where they have
to have a much thicker haunch.

43
00:02:01,110 --> 00:02:04,080
So when we talk about tall haunches here

44
00:02:04,080 --> 00:02:07,260
or extreme haunches, we're
talking about haunches

45
00:02:07,260 --> 00:02:09,900
in the range of about five to 15 inches,

46
00:02:09,900 --> 00:02:11,460
significantly higher

47
00:02:11,460 --> 00:02:15,330
or larger than what we would
use on a standard haunch.

48
00:02:15,330 --> 00:02:17,040
A lot of times when this happens,

49
00:02:17,040 --> 00:02:20,610
if it's a construction
problem, the girders are up,

50
00:02:20,610 --> 00:02:23,370
you know, the contractors
trying to build the bridge,

51
00:02:23,370 --> 00:02:26,370
we're trying to minimize the impact

52
00:02:26,370 --> 00:02:27,660
on the traveling public,

53
00:02:27,660 --> 00:02:29,010
but all of a sudden you have this problem

54
00:02:29,010 --> 00:02:30,060
that needs to be fixed

55
00:02:30,060 --> 00:02:31,680
and you have to kind of come up

56
00:02:31,680 --> 00:02:34,710
with a detail that allows you
to have this extreme haunch.

57
00:02:34,710 --> 00:02:37,740
And there's some questions about
how it impacts the strength

58
00:02:37,740 --> 00:02:41,100
of a composite concrete or
a composite steel girder

59
00:02:41,100 --> 00:02:43,830
and that's what we were
trying to focus on here.

60
00:02:43,830 --> 00:02:47,250
This project, it was a relatively unique

61
00:02:47,250 --> 00:02:48,090
in that a lot of times we'll

62
00:02:48,090 --> 00:02:50,520
say there's a steel girder bridge project

63
00:02:50,520 --> 00:02:52,500
or a concrete girder bridge project.

64
00:02:52,500 --> 00:02:54,960
This considered both steel
and concrete girders.

65
00:02:54,960 --> 00:02:57,570
And in order to study the behavior,

66
00:02:57,570 --> 00:03:00,390
we really needed to do
some full scale testing.

67
00:03:00,390 --> 00:03:02,400
Okay, when I say full scale,

68
00:03:02,400 --> 00:03:06,270
I mean trying to test
reasonable size girders

69
00:03:06,270 --> 00:03:10,530
along with the geometry
that would be existing

70
00:03:10,530 --> 00:03:11,700
in these haunched regions.

71
00:03:11,700 --> 00:03:13,383
So they consisted of,

72
00:03:14,310 --> 00:03:18,600
I'll call them full scale laboratory test

73
00:03:18,600 --> 00:03:20,310
doing what we call a push-out test

74
00:03:20,310 --> 00:03:22,200
where even though we're
simulating a girder,

75
00:03:22,200 --> 00:03:23,550
we would actually do our tests

76
00:03:23,550 --> 00:03:27,780
in a large frame where we
subject large shear forces

77
00:03:27,780 --> 00:03:29,370
between the simulated deck

78
00:03:29,370 --> 00:03:31,320
and the simulated girders on them.

79
00:03:31,320 --> 00:03:34,560
So we did extensive laboratory tests

80
00:03:34,560 --> 00:03:37,830
on both steel and concrete,
you know, girder systems.

81
00:03:37,830 --> 00:03:41,760
And then we use that data
to validate computer models

82
00:03:41,760 --> 00:03:43,710
that allowed us to then
look a little bit more

83
00:03:43,710 --> 00:03:48,603
at the wider range of geometries
using computational models.

84
00:03:49,440 --> 00:03:52,560
- What we found, very interestingly,

85
00:03:52,560 --> 00:03:55,350
is our current practice can be

86
00:03:55,350 --> 00:03:58,360
expanded to deeper haunch levels

87
00:03:59,880 --> 00:04:04,880
and with very minor modifications
to our existing standards.

88
00:04:06,090 --> 00:04:08,220
And then they also provided
a bit more guidance

89
00:04:08,220 --> 00:04:12,150
onto what other things we can do

90
00:04:12,150 --> 00:04:14,250
that would achieve the same purpose.

91
00:04:14,250 --> 00:04:15,900
- You get these problems in the field

92
00:04:15,900 --> 00:04:19,680
and you want to have a
solution, this is a relatively,

93
00:04:19,680 --> 00:04:21,450
you know, common problem
where things come up

94
00:04:21,450 --> 00:04:24,360
and the geometries
suddenly necessitate maybe

95
00:04:24,360 --> 00:04:27,000
increasing the haunch above
what you normally would have.

96
00:04:27,000 --> 00:04:27,930
I think this research

97
00:04:27,930 --> 00:04:30,180
provides a good solution to those problems

98
00:04:30,180 --> 00:04:33,903
and hopefully trying to avoid, you know,

99
00:04:35,250 --> 00:04:37,500
any delays and so on that that may end up

100
00:04:37,500 --> 00:04:39,660
impacting the construction schedules.

101
00:04:39,660 --> 00:04:40,860
- [Announcer] For more information

102
00:04:40,860 --> 00:04:43,260
and to find the publication
for this project,

103
00:04:43,260 --> 00:04:45,600
please visit the TxDOT Research Library

104
00:04:45,600 --> 00:04:46,803
at the link shown below.