1
00:00:00,067 --> 00:00:05,067
(soft music)
(logo whooshing)

2
00:00:07,500 --> 00:00:08,550
- [Announcer] Recent updates

3
00:00:08,550 --> 00:00:11,520
to AASHTO Bridge Design Specifications

4
00:00:11,520 --> 00:00:14,790
allow for the use of
high-strength reinforcing steels

5
00:00:14,790 --> 00:00:18,305
with yield strengths up to 100 KSI.

6
00:00:18,305 --> 00:00:22,290
80 KSI and 100 KSI steels are available,

7
00:00:22,290 --> 00:00:24,750
but questions about durability, cracking,

8
00:00:24,750 --> 00:00:26,790
and how to best use these materials

9
00:00:26,790 --> 00:00:29,910
have prevented their
full adoption in Texas.

10
00:00:29,910 --> 00:00:32,070
The Texas Department of Transportation

11
00:00:32,070 --> 00:00:35,520
and researchers with the Center
for Transportation Research

12
00:00:35,520 --> 00:00:38,040
examined bridge components to identify

13
00:00:38,040 --> 00:00:39,750
where these high-strength steels

14
00:00:39,750 --> 00:00:41,970
could benefit Texas bridges.

15
00:00:41,970 --> 00:00:44,670
- Grade 40 reinforcing steel was followed

16
00:00:44,670 --> 00:00:48,960
by the current standard
Grade 60 reinforcing bars,

17
00:00:48,960 --> 00:00:52,980
and now development basically carries on.

18
00:00:52,980 --> 00:00:55,800
And Grade 80 and Grade 100

19
00:00:55,800 --> 00:00:58,710
and those numbers imply the yield strength

20
00:00:58,710 --> 00:01:03,270
of the reinforcing bars is
getting into the marketplace.

21
00:01:03,270 --> 00:01:07,230
And the availability
of these new materials

22
00:01:07,230 --> 00:01:10,350
had to be investigated prior to deployment

23
00:01:10,350 --> 00:01:13,590
in projects within the state of Texas.

24
00:01:13,590 --> 00:01:16,380
For service-related questions,

25
00:01:16,380 --> 00:01:20,310
the best tool that we can
use is large-scale testing.

26
00:01:20,310 --> 00:01:22,200
So the research took place

27
00:01:22,200 --> 00:01:25,560
at Ferguson Structural
Engineering Laboratory

28
00:01:25,560 --> 00:01:28,860
because the questions that
we're trying to tackle are:

29
00:01:28,860 --> 00:01:31,140
If you're using this
high-strength material

30
00:01:31,140 --> 00:01:33,840
and lesser quantities of it,

31
00:01:33,840 --> 00:01:37,590
the cracking that can occur
under service conditions,

32
00:01:37,590 --> 00:01:40,140
is that gonna be any worse, similar to,

33
00:01:40,140 --> 00:01:43,080
or better than what we have in the case

34
00:01:43,080 --> 00:01:45,780
of conventional materials
that we're using right now?

35
00:01:45,780 --> 00:01:49,620
So we tackle that goal by
conducting large-scale testing.

36
00:01:49,620 --> 00:01:50,940
For the second part,

37
00:01:50,940 --> 00:01:52,830
which is the strength piece,

38
00:01:52,830 --> 00:01:54,780
there are two different components,

39
00:01:54,780 --> 00:01:58,530
and that is we have barriers
within the design codes

40
00:01:58,530 --> 00:02:01,530
that will specifically call out and say

41
00:02:01,530 --> 00:02:03,930
the code provision that you're using

42
00:02:03,930 --> 00:02:08,657
for this purpose or that purpose
is valid up until 80 KSI,

43
00:02:09,576 --> 00:02:12,180
60 KSI, some other limit,

44
00:02:12,180 --> 00:02:15,570
which establishes the
boundaries of our knowledge.

45
00:02:15,570 --> 00:02:17,970
And by eliminating those boundaries

46
00:02:17,970 --> 00:02:20,160
through large-scale testing,

47
00:02:20,160 --> 00:02:21,900
we were able to tackle

48
00:02:21,900 --> 00:02:25,230
those strength-related questions as well.

49
00:02:25,230 --> 00:02:26,640
In a nutshell,

50
00:02:26,640 --> 00:02:30,330
the use of Grade 80 and
Grade 100 reinforcement,

51
00:02:30,330 --> 00:02:31,560
so high-strength steel,

52
00:02:31,560 --> 00:02:36,210
within Texas reality
is very much possible.

53
00:02:36,210 --> 00:02:40,860
And testing results that we have gathered

54
00:02:40,860 --> 00:02:44,220
basically support the deployment
of these new materials

55
00:02:44,220 --> 00:02:47,640
in cases where they are used make sense.

56
00:02:47,640 --> 00:02:49,140
So these new materials,

57
00:02:49,140 --> 00:02:51,000
when they get in the marketplace,

58
00:02:51,000 --> 00:02:53,580
it's not one size fits all.

59
00:02:53,580 --> 00:02:56,340
In some cases where we have congestion

60
00:02:56,340 --> 00:02:58,590
in the reinforcing bar cages,

61
00:02:58,590 --> 00:03:00,570
in cases where we would like to use

62
00:03:00,570 --> 00:03:04,980
this higher-grade material
but a lesser quantity of it,

63
00:03:04,980 --> 00:03:08,460
at the expense of spending
a little more money

64
00:03:08,460 --> 00:03:11,700
on the high-strength
steel but a lot less money

65
00:03:11,700 --> 00:03:13,620
on the labor side,

66
00:03:13,620 --> 00:03:15,750
we may be able to justify its use.

67
00:03:15,750 --> 00:03:18,600
And it's the next tool in the toolbox

68
00:03:18,600 --> 00:03:22,950
that's available for bridge
designers and contractors alike.

69
00:03:22,950 --> 00:03:24,210
- [Announcer] For more information

70
00:03:24,210 --> 00:03:27,240
and to find the publications
for this project,

71
00:03:27,240 --> 00:03:29,910
please visit the TxDOT Research Library

72
00:03:29,910 --> 00:03:31,623
at the link shown below.