....

TECHNICAL REPORT STANDARD TlTlEPAGE ~------~~~~~~~~~----------~1.-=-Re-p-or_"""':t N7"o-. -~~~--~--r::;-2.-;G;::-0-:":Y.:-:-:rn=m-=en:-t ";;"'Ac=ce:::-s:-::-:sio~No. 3, Ritcipieni's Catol09 No,

FmJA/TX -Pi4134f2'62 -i 1 h4~.--:;-T,:-:";-t'-" -on-;-d7Su7b~tit-;-le-------:--.L------------'-'----+-=-5.--=-Re-po-rt-=O:--0t-e-:-----·--·-·--·---·--"--- -.. -. ---

Design and Tests of a Precast Concrete Barrier for Work Zones

July 1983 ---------6.- P ";'0 rm i nil, Or90ni lotion Cod ..

-~, '

7, Author( 51 - .. ------~-,----------~ ---~ Performing Or90l,i,otion R"p~tI N"

Hayes E. Ross, "Jr., and Dean L. Sicking

-9. Perfo;ming Organi %otion No";e and Address

Texas Transportation Institute The Texas A&M University' SYstem Coll ege Station, Texas 77843

Research Report 262-1 10, Work Unit No,

11. Controct or Gront No.

Study No. 2-18-79-262 13. Type o·f Report ond Period Cove_red

~~-----''---:---:-::-7;-- '-----:--'------'--"'----; - September 1978 12. Sponsoring Allency Nomi. and Address - Interim _ -

Texas .. State -, Department of 'Hi ghways, July 1983 arid Public Transportation --~~--:-4

11 th and- Brazos Streets 14. Sponsoring Agency Code

Austin, Texas 78701 IS. Supplementory Notes

Research performed in cooperation ,with SDHPT, DOT, and FHWA. Research Study Titl e: Safety Devi ces for Hi ghwayWork Zones

16. Abstroct

A portable'precast concrete, traffic barrier has been designedwhichutilizes 15 ft (4.6m) barrier segments. The barrier should be much more portable than barriers currently in use in Texas which employ 30ft (9.1 m) segments. _ Barrier segment~ are attached with two C5x, 9 steel splice channels and four 1-1/8 ill. _' (2.86 cm)steel bolts. Thi sjoint constructionprovi des si gnificantjoi ntmoment capacity without Significantly complicating barrier insta'llation. .-

The barri'er.,was successfully crash tested with a 4500 lb (.2045 kg) vehicle impacting at 25 degrees and60rilph (96.6 km/hL The test vehicle Was smoothly.· redirected, and vehicleacceleratiQns were within nationally accepted guidelines. No barrier segments were damaged during testing, and only a few splice channels required repair or, replacement. Portable barriers currently in use on Texas hignwaysweredamaged moresever:-ely when tested under identical conditions.

17. Key Words

Traffic Barrier, Concrete, Precast, Work Zone, Construction, Crash Test

'18, Distribufion Stotem~nt

No restrictions. This document ;s available to the public through the National'Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 22161~

19. Security Clossif. Cof this report) 20, Security Clossil. (of 'hi $ page) 21. No. of Pages 22. P ri ce

Unclassified Unclassified 61 Form DOT F 1700.7 (8-69)

DESIGN AND TESTS OF A PRECAST CONCRETE BARRIER FOR WORK ZONES

Hayes E. Ross, Jr. Research Engineer

and

Dean l. Sicking Engineering Research Associate

Research Report 262~1 on

Research Study No. 2-18-79-262 Safety Devices for Highway Work Zones

Sponsored by

Texas State Department of Highways and Public Transportation

in cooperation with

The U. S. Department of Transportation Federal Highway Administration

July 1983

Texas Transportation Institute Texas A&M University

College Station, Texas

DISCLAIMER

The contents of this report reflect the views of the authors, who are

responsible for the opinions, findings, and conclusions presented herein.

The contents do not necessa ri 1y ref1 ect the offi ci a 1 vi ews or pol i ci es of

the Texas State Department of Highways and Public Transportation or the

Federal Highway Administration. This report does not constitute a standard,

specification, or regulation.

KEY WORDS

Traffic Barrier, Concrete, Precast, Work Zone, Construction, Crash Test

ACKNOWLEDGMENTS

Thi s research study was conducted under a cooperati ve program between

the Texas Transportation Institute, the Texas State Department of Highways

and Public Transportation, and the Federal Highway Administration.

;;

TABLE OF CONTENTS Page

INTRODUCTION ! 1

RESEARCH APPROACH 5

Joint Moment Capacity 6 Joint Connection Slack 11

_ Roadway Friction 12

PORTABLE CONCRETE TRAFFIC BARRIER DESIGN 17

CRASH TESTS 23 -

Test 1 23 -Test 2 29

CONCLUSIONS 36

APPENDIX A. SEQUENTIAL PHOTOGRAPHS 37

APPENDIX B. ACCELEROMETER TRACES AND PLOTS OF ROLL, 42 PITCH, AND YAW RATES

REFERENCES 55

iii

LIST OF FIGURES

Figure No.

1 Texas P~>rtable Concrete Barrier, Dowel Bar Connection. 2

2 A Typical Concrete Barrier, Pin Joint Connection. 3

3 Lateral Joint Displacement versus Segment Length, 9 Variable Connection Moment .

4 Lateral Joint Displacement versusConnecUon Moment, 10 Variable Segment Length

5 Lateral Joint Displacement versus Connection Slack, 14 Variable Segment Length

6. Lateral Joint Displacement vers:us Segment Length, 16 Variable Frl~ction

7 Joint Connection Using Steel Plate 19

. 8 Construction Detail sfor Portable Concrete Barrier with 20 lap~Splice Connections

. 9 Summary of Test 1 24

10 Test Vehicle and Barrier Before Test 125

11 . Test Vehicle After Test 1 26

12 Barrier After Test 1 27

13 Barrier Joint After Test 1 28

14 Joint Connection Using Steel Channel 30

15 . Summary of Test 2 31

16 Test Vehicle and Barrier Before Test 2 32

17 Test Vehicle After Test 2 33

18 Barrier After Test 2 34

19 Barrier Joint After Test 2 35

20 Sequential Photographs for Test 1 38

21 Sequential Photographs for Test 2 40

22 Accelerometer Trace for Test 1 .. Longitudinal Direction 43

23 Accelerometer Trace for Test 1 - Lateral Direction 44

iv

Figure No.

24

25

26

27

28

·29

30

31

32

33

LIST OF FIGURES (continued)

Pase

Accelerometer Trace for Test 1 - Vertical Directlon 45

Vehicle Roll Versus Time for Test 1 46

Vehicl e Pitch Versus Time for Test 147

Vehlcl e Yaw Versus Time for Test 1 48

Accelerometer Trace for Test 2 ... Longitudinal Direction 49

Accelerometer Trace for Test 2 - Lateral Direction 50

Accelerometer Trace for Test 2 .. Vertical Direction 51

Vehicle Roll Versus Time for Test 2 52

Vehicle Pitch Versus Time for Test 2 53 .

Vehicle Yaw Versus Time for Test 2 54

v

LIST OF TABLES

Table No. Page

1 Length of Need and Critical Impact 7 Point Study Results

2 Connection Moment-Segment Length- 8 Deflection Study

3 Connection Slack-Segment Length- 13 Deflection Study

4 Friction Variation Study Results 15

vi

I NTRODUCTI ON

Although for many years considerable emphasis has been placed on safety

along completed portions of the highway system, only recently has concern

been shown for the hazards that exi st on hi ghways under constructi on or

repair. During expansion or repair of an existing highway, construction

equipment and workers are usually operating very close to the travelway.

This situation can be hazardous for both motorists and workmen. Often a

positive barrier is warranted to prevent errant vehicles from entering the

work zone.

Ideally, a positive barrier should be capable of safely redirecting

velTi-cles impacting at speeds up to 60 mph (96.6 km/h) and angles up to

25 degrees. Lateral deflections of the barrier resulting from impacts

should be small to protect workers standing behind the barrier. Finally,

the barrier should be relatively portable since it may be moved within a

work zone several times during a single construction project.

Many state highway departments have used segmented precast concrete

barriers in construction zones. The segment lengths and connection details

of these barriers vary greatly from state to state. Some of the designs

currently in use are summarized in Figures 1 and 2. Some of these barriers

have performed well when struck by errant vehicles, while others have shown

seri ous defi ci end es. The Texas State Department of Hi ghways and Pub 1 i c

Transportati on has had good success with segment lengths of 30 ft (9.1 m)

and a dowel bar connection as shown in Figure 1 (l). Precast concrete bar­

riers weigh as much as 500 lb/ft {745 kg/m} and therefore 30 ft (9.1 m) seg­

ments are not very portable. Segment lengths from 12 to 20 ft (3.7 to

6.1 m) would be much more portable than the current 30 ft (9.1 m) length

1

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. FIGURE 10 TEXAS PORTABLE CONCRETE BARRIER, DOWEL BAR CONNECTION.

2

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ars

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1" Dia.x 21_211 Rod Threaded at top to accept hex nut

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PIN CONNECTION DETAIL (Tack vie 1 d nut to rod) I' FOR TH1PORARY INSTALLATION

FIGURE I. A TYPICAL CONCRETE BARRIER, PIN JOINT CONNECTION.

5/811 Dia. Steel Hinge Bars (2 Per End)

used in Texas. A review of the literature revealed that tests of 12 and 20

ft (3.7 and 6.1 m) pin-jointed precast segments had been only partially

successful (£,1). Tests indicate that at a high speed, high angle impact a

vehicle will likely override the barrier and/or roll over subsequent to

impact.

This study was therefore undertaken to develop a portable precast

concrete barrier which would a) safely redirect vehicles impacting at a

speed of 60 mph (96.6 km/h) and an angle of 25 degrees; b) deflect only a

short distance during· high-speed and high-angle impacts; and c) be

relatively portable.

4

RESEARCH APPROACH

Tests have shown that if a segmented concrete barrier remains intact

during impact, the barrier1s capacity for safely redirecting an errant vehi­

cle will be determined by the amount of rotation and lateral movement of the

segments. Segment rotation and movement is dependent on segment-to-segment

joint properties (torque and moment capacity and slack), barrier segment

length, barrier mass, and friction between barrier and the surface on which

it rests. The re 1 at i onshi p between these properties and the dynami c re­

sponse of a barrier must be understood if an optimum design for a portable

concrete traffic barrier (PCTB) is to be developed.

Contri buti ons of each of these parameters to the behavi or of a PCTB

cannot be fully determined through full-scale crash testing due to the inor­

dinate expense of such a program. Therefore a barrier simulation program

developed by TTl to model a PCTB (!) was employed to study these parameters.

This simulation is a two-dimensional program that computes the lateral move­

ment and yaw of the barrier segments for a given lateral impulse. It does

not predict vehicle response and as such vehicle/barrier interaction is not

considered. However, vehicle behavior can be inferred from previous tests

of segmented concrete barriers (£,1) in which barrier movement was known. A

series of computer runs were made to evaluate the effects of barrier length,

joint moment capacity, joint slack, and roadway friction on lateral barrier

deflections by varying each parameter independently. The impulse applied to

the barrier in each of these runs was obtained from full-scale test measure­

ments (~), specifically, force-time measurements for a 60 mph, 25 degree

impact. Since this analysis was designed to model barrier response to the

most vigorous test that the barrier would be expected to withstand, all

5

simulations modeled impact with a 4500 lb (2043 kg) vehicle traveling at 60

mph" (96.6 km/h) at an angle of 25 degrees. For all simulations, the impact

point was located approximately at the third point of the system.

A sensitivity analysis was initially conducted to determine the length

of barrier system required to eliminate significant end point movement and

the location of the critical impact point with respect to a barrier segment.

Significant end point movement was arbitrarily defined as 2 in. (5.08 cm) of

displacement. This analysis was conducted with no joint moment capacity and

a coefficient of friction of 0.7 between barrier and roadway surface.

The results of the initial analysis are summarized in Table 1. Bar­

riers with segment lengths equal to or greater than 20 ft (6.1 m) require

approximately 120 ft (36.6 m) of barrier to eliminate significant end point

movement. However, those barriers with shorter segment lengths require

approximately 180 ft (54.9 m). Also shown in this table is that impacts at

the center of a joint cause larger deflections for all segment lengths

except the 30 ft (9.1 m) segments.

Joint Moment Capacity

The effects,of joint moment capacity, Mu, on maximum barrier deflec­

ti ons were exami ned by combi ni ng each segment 1 ength under i nvesti gat ion

with five joint moment capacities ranging from 0 to 100 kip-ft (0 to 1356

kN-m). The joint slack, 4>s, was assumed to be 3 degrees and the elastic

limit, ~e' was 5 degrees. No failure limit was established. The coeffi­

cient of friction between the barrier and the roadway surface was assumed to

be 0.7.

Results of these simulations are given in Table 2 and Figures 3 and 4.

As shown in these figures, the effects of increased joint moment capacity on

6

TABLE 1. LENGTH OF NEED AND CRITICAL IMPACT POINT STUDY RESULTS

Segment No. Max. End Point Displacement Length of Impact Def1. Xl

in.Ylcm) X2

in.Ytcm) (ft){m) Segments Point in. (cm) in. (cm) in. (cm)

12 (3.66) 8 JT 34 (86) 2.3 (5.8) -0.1 (-0.3) -4.8 (-12.2) 0.0 (0.0) 12 (3.66) 10 JT 33 (84) 2.0 (5.1) 0.2 (0.5) -4.0 (-10.2) 0.0 (0.0) 12 (3.66) 12 JT 31 (79) 1.8 (4.6) 1.2 (3.0) -3.2 (-8.1) 0.0 (0.0) 12 (3.66) 12 CTR 39 (99) 3.7 (9.4) 0.2 (0.5) -3.2 (-8.1) 0.0 (0.0) 12 (3.66) 15 CTR 35 (89) 2.3 (5.8) 0.7 (l.8) -2.9 (-7.4) 0.0 (0.0)

15 {4.57} 8 CTR 43 (109) 4.7 (11.9) -0.5 (-1.3) -3.7 (-9.4) 0.0 (0.0) 15 (4.57) 8 JT 26 (66) 1.3 (3.3) -0.2 (-0.5) -2.2 (-5.6) 0.0 (0.0) 15 (4.57) 10 CTR 39 (99) 3.6 (9.1) 0.1 (0.2) -3.7 (-9.4) 0.0 (O.O) 15 {4.57} 12 CTR 35 (89) 2.9 (7.4) 0.5 (1.3) -2.9 (-7.4) 0.0 (0.0)

20 (6.10) 5 CTR 34 (86) 1.3 (3.3) 0.0 (0.0) 4.3 (10.9) 2.8 (7.11) 20 (6.10) 6 CTR 32 (81) 2.5 (6.4) 0.0 (0.0) 0.2 (0.5) -0.1 (-0.3) 20 (6.10) 6 JT 24 (61) 1.0 (2.5) 0.2 (0.5) 1.2 (3.0)· 0.2 (0.5)

25 (7.62) 5 CTR 22 (56) 0.1 (0.3) 0.2 (0.5) -1.8 (-4.6) 2.4 (6.1) 25 (7.62) 5 JT 21 (53) 0.2 (0.5) -0.2 (-0.5) -1.2 (-3.0) -1.7 (-4.3)

30 (9.14) 3 CTR 18 (46) 0.1 (0.3) -1.0 (-2.5) 1.7 (4.3) -13.3 (-33.8) 30 (9.14) 4 CTR 14 (36) 0.2 (0.5) -1.2 (-3.0) -0.4 (-1.0) 1.7 (4.3) 30 (9.14) 4 JT 17 (43) 0.5 (1.3) 2.0 (5.1) 0.4 (1.0) -0.6 (-1.5)

7

Barrier Segment Length

ft (m)

12 (3.66)

15 (4.57)

20 (6.10)

25 (7.62)

30 (9.14)

TABLE 2. CONNECTION MOMENT-SEGMENT LENGTH-DEFLECTION STUDY

~ • = 30 ~ = 50 'fs 'fe .

Connection Maximum Moment Displacement

k-ft {kN-m) in. (cm}

o (0) 35.01 (88.93) 25 (33.9) 25.21 (64.03) 30 (40.7) 23.92 (60.76) 50 (67.8) 19.80 (50.29) 75 (102) 19.76 (50.19)

100 (136) 21.67 (55.04)

o (0) 35.31 (89.69) 25 (33.9) 29.06 (73.81) 30 (40.7) 27.93 (70.94) 50 (67.8) 22.73 (57.73) 75 (102) 19.98 (50.75)

100 (136) 18.76 (47.65)

o (0) 33.80 (85.85) 25 (33.9) 28.01 (71.15) 30 (40.7) 26.94 (68.43) 50 (67.8) 26.70 (67.82) 75 (102) 21.87 (55.55)

100 (136) 19.07 (48.44)

o CO) 22.32 (56.69) 25 (33.9) 21.37 (54.28~ 30 (40.7) 21.17 (53.77 50 (67.8) 19.89 (50.52) 75 (102) 18.82 (47.80)

100 (136) 18.34 (46.58)

o (0) 17.74 (45.06) 25 (33.9) 16.87 (42.85) 30 (40.7) 16.80 (42.67~ 50 (67.8) 16.55 (42.04

.75 (102) 16.25 (41.28) 100 (136) 15.98 (40.59)

8

.--.. +J tr-

+J t: (lJ E (lJ U 10

.r-0_ I/')

'r-0

+J c

'r-0 'J

r-IO ~ (lJ +J 10

.....J

E :J E

'r-'

X 10

:E:

3.0

2.5

2.0

1.5

1.0

.5

f1 u

o o

f1 =0 u

M =25 u

lG 15 20 Barrier Segment Length (ft)

25 30

Friction Coefficient ~0.7

30 50 A~

FIG. 3. Lateral Joint Displacement versus Segment Length, Variable Connection Moment.

9

..-.. +l 'I-

.'--'

+l s:::: (l) E (l) U «:1 r-c_ VI ...... e +l s::::

'r-0 'J

r-«:1 s... <lJ +l «:1 -l

E :l E ..... x ttl ::E:

3.0

2.5

2.0

1.5

1.0

.5

o o

L=30'

"

25 50 75 Connection Moment (k~p~ft)

FIG. 4. . Lateral Joint Disolacement versus Connection r1oment, Variable" Segment Length.

10

100

barrier deflections decrease as the barrier segment lengths increase. This

can be understood if the relative joint rotations due to a barrier deflec­

tion of 1 ft (0.30 m) are examined for several segment lengths. The rela­

tive joint rotations of 12 ft, 20 ft, and 30 ft (3.7 m, 6.1 m, and 9.14 m)

segments subjected to 1 ft (0.30 m) lateral displacement are 9.5, 5.7, and

3.8 degrees, respectively. Since joint rotations are larger for short seg­

ments, more energy is absorbed in the barrier joints and a larger portion of

the energy absorbed is dissipated in plastic deformation of the joint than

for long segments.

Although the 12 ft (3.6 m), 15 ft (4.6 m), and 20 ft (6.1 m) segment

lengths with no joint moment capacity were deflected approximately the same

distance, the 12 ft length deflected less for moderate moment capacities

than did the two intermediate segment lengths. The 15 ft (4.6 m) and 20 ft

(6.1 m) segment lengths were deflected less than the 12 ft (3.6 m) length

for barriers with large joint moment capacities. The results of this phase

of the study have shown that a) moderate joint moment capacity will effec­

tively reduce deflections of short barrier segments; b) intermediate segment

lengths require large joint moment capacities to insure similarly reduced

deflections; and c) deflections of long barrier segments are not reduced

significantly by large joint moment capacities.

Joint Connection Slack

The effects of connection slack on maximum barrier deflection were

investigated by varying connection, <Ps, slack from 1 to 8 degrees for each

of the five barrier lengths. The ultimate moment was held constant at 100

kip-ft (136 kN-m), and the elastic limit was 2 degrees larger than the slack

11

rotational limit. The coefficient of friction between the barrier and the

roadway was 0.7.

Results of the simulations are given in Table 3 and are plotted in

Figure 5. The curves in Figure 5 show a general increase in deflection as

the connection slack grows. However, for segment lengths of 20 ft (0.61 m)

and less there is no significant increase in barrier deflections below a

joint slack of 5 degrees.

Roadway Friction

The effects of surface friction on maximum barrier displacement were

examined for barrier lengths of 20 ft (0.61 m) and less. Segment lengths in

excess of 20 ft (0.61 m) were not considered portable enough to warrant fur­

ther study, si nce the shorter segments had been shown to be capable of

redirecting vehicles without deflecting excessively. For this investigation

the coefficient of friction was varied from 0.4 to 0.6. A joint moment

capacity of 150 kip-ft (2.03 kn-m), a slack rotati on of 1 degree, and an

elastic limit of 3 degrees were used in all tests.

Results of these simulations are shown in. Table 4 and Figure 6. As

expected-, an increase in friction reduced maximum barrier deflections.

12

Length ft (m)

12 (3.66)

15 (4.57)

20 (6.10)

25 (7.62)

30 (9.14)

TABLE 3. CONNECTION SLACK-SEGMENT LENGTH-DEFLECTION STUDY

Mu = 100 k-ft ~e = ~s + 2°

Slack (deg)

1 2 3 5 8

1 2 3 5 8

1 2 3 5 8

1 2 3 5 8

1 2 3 5 8

13

Lateral Displacement

ft {m}

1.59 (0.48) 1. 70 (0.52) 1.76 (0.54) 1.45 (0.44) 1. 71 (0.52)

1.45 (0.44) 1.50 (0.46) 1.56 (0.48) 1.65 (0.50) 1.99 (0.61)

1.37 (0.42) 1.53 (0.47) 1.59 (0.48) 1.92 (0.59) 2.34 (0.71)

1.13 (0.34) 1.34 (0.41) 1.53 (0.47) 1.75 (0.53) 1.86 (0.57)

1.06 (0.32) 1.22 (0.37). 1.33 (0.41 ~ 1.43 (0.44 1.43.(0.44)

3~5

3.0

...., 4-

...., t: 2.5 0) E 0) 20' u (Ij

ro-CL III 'r-0 ...., t:

or-o "J

t-(Ij S-O) ...., (Ij.

---l

E !:l E 'r-x (Ij

:::

2.0 15 '

25' 12'

1.5 30'

1.0~ __ ~ __ ~ __ ~~ ______ ~ ____________ ~ ______ __ 123 5

M =100 k-ft u .

4> = 4> + 20 e s

11=0.7

Connection Slack (deg)

FIG. 5. -.Lateral Joint Displacement versus Connection Slack, Variable" Segment Length.

14

LENGTH (ft)

12

15

20

TABLE 4. Friction Variation Study Results

~ = 10 ~ = 30 M = 150 k-ft s e u

FRICTION LATERAL COEFFICIENT DEFLECTION

(11) (ft)

0.4 1.68 0.5 1.61 0.6 1.50

0.4 1.68 0.5 1.60 0.6 1.52

0.4 1.35 0.5 1.26 0.6 1.20

.I

15

.;..> s:: (I)

E Q)

U 10 r-0.. III

3.5 _

3.0

2.5

2.0 '

c; 1.5 .;..> s:: .,... o

r-;J

0 ).l = 0.4

13" ).l = 0.5

j..l = 0.6 0

1.0 L-____ ~ ________ ~ ________________ ~ ______ __

10 12 15 20 Barrier Segment Length (ft)

150 k-F

FIG. 6. Lateral Joint Displacement versus Segment Length, Variable Friction.

16

PORTABLE CONCRETE TRAFFIC BARRIER DESIGN

The previous analysis had shown that a PCTB with short barrier segments

could withstand severe impacts without deflecting excessively if the barrier

joints had sufficient moment capacity, limited slack, and the ability to

defonm plastically. Therefore researchers concluded that an optimum design

for a PCTB could be developed with barrier segment lengths beween 12 and 20

ft (3.7 m and 6.1 m) which would be more portable than those currently in

use on Texas highways.

Three of the parameters ; nvesti gated prev; ous 1y -- barri er segment

length, joint moment capacity, and joint slack -- can be controlled by the

barrier design. Roadway surface friction cannot be entirely controlled by

the design of the barrier and as shown previously, short segment lengths can

perform acceptably with low friction if the barrier is designed properly.

Therefore a design for a peTB was developed by estimating the optimum seg­

ment length, joint moment capacity, and slack. /

The key to increasing portability of a segmented concrete traffic bar-

rier is determining the optimum barrier segment length. Long segments are

very heavy and must be moved by heavy equi pment. However, very short seg­

ments requi re many j oi nts for the same barri er 1 ength as one long barri er

segment. Thus the optimum segment length is the longest segment that can be

. installed without great difficulty due to the weight of each segment. It

was concluded that 15 ft (4.6 m) is an optimum length of a peTB barrier seg­

ment since a 15 ft (4.6 m) segment could be moved with little more diffi­

culty than a 12 ft (3.7 m) segment. Further, the state of Texas currently

uses a 30 ft (9.1 m) segment, and two 15 ft (4.6 m) segments could be cast

in existing forms.

17

Previous analysis has shown that a joint moment capacity of 100 kip-ft

(136 kn-m) would be required to minimize deflections and that a joint slack

of 3 degrees is acceptable if the joint was capable of 7 degrees rotation

before lockup occurs. A jOint was designed which utilizes two 1/2 in. x

5 in. (1.27 cm x 12.7 cm) steel splice plates for development of joint

moment capacity. The assembly of this barrier joint requires that two seg­

ments be placed end to end with a small space between. Two splice plates

and four 1-1/8 in. (2.86 cm) dia. bolts are then used to connect the seg­

ments as shown in Figure 7.

Barrier segments were designed to withstand impact forces and joint

loads predicted by the computer analysis. Construction drawings of the bar­

rier are shown in Figure 8. Special reinforcement was required near the end

of the barrier segments due to large stresses which develop near each joint

during'impact. Bearing pads at the ends of each segment help reduce damage

to the barrier when the joint rotates to lockup.

18

FIGURE 7. JOINT CONNECTION USING STEEL PLATE.

6" 6" 0

411 411 0. >, I-..........

SR2,Bar = N

1 1/411 Bars

12" r r--. 1

(1) 1 -

N

r--. Anchorage Plate (Deta i 1#1)

r--. ,$plice Plate (Deta i 1 #2) ,

"-10" 1 1/811 Dia o Bolt

r-

1 1/4" Dia. Pipe SECTION A-A

(Y")

, TSDHPT CLASS C 1 1/4" ~ CONCRETE (3600 psi min.) U ·.J211 r

V1 Bar 2 1 -31/411

SECTION 8-B

.~ ,/ ",1-- •. "

20

111 R

V,Bars

SR1 Bar 1011 R

r--. 1

-0", "'-~------;r- 1 -N

o r-

30"

L-I-.--+----t-----t~5-2" Di a. Ho 1 es

.. I 4 4ti~i~~ " ~1/2" 4" 2 16" P1 2-1 3/4" Dia.Bolt Holes-I -1 x x.· •

-..

-N '-r-

10 ~2 II

3" R n N

1 -M

BAR V2 (#6)

DETAIL #1

42"

L-----t--2-1 1/2" Dia. x 2 3/4" Bolt Holes (Typ. Both Ends)

1/2" x 5" x 3 1 -6"

DETAIL # 2

2 1/4" •

1 1/4·

12' r = \0

1

r-N

1 -0 N

7*41 1

1 II r-

1 .. 9Y2

1 BAR SR2 BAR SR1 (#4 ) (#4)

REINFORCING STEEL DETAILS (~oT.S.)

(GRADE 60 STEEL)

1'-2 3/4" BAR TRl

(#4 )

Splice PL (Detail #2)

o r-

I

r-

2"

14'-11"

"-10"

Anchorage Plate (See Detail #1)

- -it -t+ - --..:.....- ---=- -I f I I 11=1 I-===- ~--

.L-_ ==:::!!:===~~~~T 300 ------------------------~

~ 1 1/4" Dia.-r---.-., 2-1 1/8" Dia. x 21-4" Bolts Pipe (A-325) Note: A-321 Thrd o Rods surrounding 11-0 1/2,1 14 1/2/1 may be used. Tack weld nuts to rods bo lt I------+-~

SRz Bars

{ I

PLAN VIEt'>! (Typo Both Ends)

V Bars (GRADE 60) 1 ~

I I I I I ,++ \1 _I a 1 -I ~I -I ·1 '1 ~I

\ I

1

I .r~V2 Rars / - 1--1'== ~- =l >--: ,.;--~/r-'

I (:) l:} I -J-I.r---- f- - ...l -1 L - ---=-l 3 j

4" 4/1 4" 4/1 6" J 6'} / 6" J 6 " I "I ~-~t 6" • .z la. ~

Bars I\nchorage Pl ate (Detail #1)

/ SR1 F~ TR1

" Spaced 24 C.C.

ELEVATION (Typ. Both Ends)

J I

J

'"

",0.

tt------

---~c~·-~-----:-,-----ff .. IG~~R~-~8·:<~-i~~~Tf~l~~g~-;~}f~]ij~~~~~~~-Rf:~~~fi~~~~~~TE·-BARPIER·'·-~:~ .. -~,--------.--:- .c·

.~

22

CRASH TESTS

The cross-sectional geometry of the New Jersey concrete median barrier

has been proven to effectively redi rect subcompact vehi c 1 e and 1 arge vehi­

cles at shallow impact angles (~). Therefore it was concluded that crash

tests with small vehicles and shallow impact angles would only duplicate

previous research. Two full-scale crash tests were conducted to evaluate

the limits of performance of the portable precast concrete traffic barrier.

Sequenti a 1 photographs selected from hi gh-speed films of the tests are

presented in Appendix A. Accelerometer traces and roll, pitch, and yaw

rates are presented in Appendix B.

Test 1

The first crash test involved a 4500 lb (2043 kg) vehicle impacting the

barrier at 60.9 mph (98.0 km/h) and 15 degrees. Figure 9 gives a sunmary of

this test. Figure 10 shows the test vehicle and barrier prior to impact.

The test vehicle was smoothly redirected and was not severely damaged as

shown in Figure 11. All maximum 50 msec average accelerations were well

below recommended 1 imits (£.). Vehi cle trajectory after impact would not

have been a hazard to other traffic.

The barrier was displaced only 0.9 ft and was not damaged significant­

ly, as shown in Figure 12. Damage to the barrier installation was limited

to superfi ci a 1 scarr; ng of the concrete surface and major deformati ons in

three splice plates. However, as shown in Figure 13, there was significant

differential horizontal movement between barriers. At large impact angles,

this differential movement could prove to be a snag point for impacting

vehicles.

23

" I ,,,..~;I' :

".:,,. .. :.,

0.038 sec 0.128s-ec ... ' 0,233 sec

\Contact at Sectio~ 5

I I ~I I ~:r I I I , .17.8° [_---~ __ ....;1.3° - ---- -- ~ /

Test No. • • . Date • • . . • Drawing Barrier Type: NJ Precast w/8" Top

and 27" bottom Installation Length-ft (m) •.•. Barrier Segment Length-ft (m) .•.•• Joi nt Connection: Two 1/2" X 5" x 42"

Slotted Steel Plates Barrier Deflection

Max. Dynamic - ft (m) . Ma.x. Permanent - ft (m) Max. Roll Angle - deg .•• ~

. .' . • • •

2262.,.1 8/17/79

180 (54.9) 15 (4.6)

1.02 (.~l) 0.92 (.28) 8.5

---- ~----

Vehic1~, • t .•.• ~ ••••• ~ ~ Vehicle Mass.- 1b(kg] •• ', • , Impact Speed - mph (km/h). • • • Impact Angle - deg ••••••• Exit Speed mph (km/h) ~ ••••• Exit Angle - deg., ••••••. Vehicle Acceleration

(max. 0.050 sec. avg.) Longitudinal -. g·s, ••••• Transvers'e - g·s. . . . • • • Vertical ~ giSt •.•• , ••

Vehicle Damage Classification TAD . . . .. . . . . . . SAE . .. . . . . . ,

FIGURE 9. SUMMARY OF TEST 1.

0.399 sec

1975 Plymouth Fury 4500 (2043) 60.9 (96.0) 17 .8 52.1 (82.1) 1.3

3.9 4.9 5.6

LFQ-4 llFLEWZ

FIGURE 10. TEST VEHICLE AND BARRIER BEFORE TEST 1.

25

FIGURE 11. TEST VEHICLE AFTER-JEST 1. ". "'.' ".-.. '

26

;1" . . il

FIGURE 12. BARRIER AFTER TEST 1.

27

FI GURE 13. BARRIER JOINT AFTER TEST .1.

28

This test was considered very successful since the test vehicle was

safely redirected and both barrier and vehicle were lightly damaged.

Test 2

After reviewing the results of test 1 it was concluded that the differ­

ential motion between barrier ends at a joint could be eliminated by

increasing the shear capacity of the jOint. This was accomplished by

replacing the steel splice plates in each joint with C5 x 9 steel channels

as shown in Figure 14. The second test was conducted with this design modi­

fication.

Test 2 involved a 4500 1b (2043 kg) vehicle impacting the barrier at a

speed of 56 mph (88~2 km/h) and an angle of 25 degrees. This test is sum­

marized in Figure 15. Figure 16 shows the test vehicle and barrier prior to

impact. The test vehicle was again redirected smoothly, and as shown in

Figure 17 was not badly damaged for a test of this severity. Maximum 50

msec average accelerations were 7.4 g's longitudinal, 7.7 g's transverse,

and 4.3 g's vertical. These acceleration levels are not high for this type

of test and are below maximum acceptable limits (~).

The maximum deflection of the barrier was only 1.3 ft (0.41 m). Damage

to concrete barrier segments was again limited to surface scarring as shown

in Figure 18. The channel splices were lightly damaged, and only six chan­

nels required replacement. There was no differential motion between barrier

ends as shown in Figure 19.

This test was considered very successful due to the safe redirection of

the test vehicle and the limited damage to the barrier.

29

. .., .

FIGURE 14. JOINT CONNECTION USING STEEL CHANNEL.

30

------------------------------------- ----

0.038 sec

Test No .... Date . . . . . Drawing Barrier Type:

. . .. . .. . . . NJ Precast W/8 11 top and 27" bottom

Installation Length - ft (m) ... Barrier Segment Length - ft (m). Joint Connection: Two 42" C5 x 9

Steel Channels Barrier Deflection

0~127 sec

~contact at Sect; on 4

2262 .. 2 8/28/82

180 (54.9) 15 (4.6)

Max. Dynamic - ft (m) •. Max. Permanent - ft (m) . Max. Roll Angle - deg .

. . • 1. 94 (0. 59 ) • .• 1.33 (0.41) .• 17.0

0~229 sec 0,382 sec

Vehicle~ ~., .•. 0 ~ 0 • ~ 1974 Plymouth Fury Vehicle Mass ... lb (kg) •. 4510 (2048) Vehicle Accelerations

(max. 0.050 sec. avg.) Longitudinal - gts. •. 7.4 Transverse ... g's. • •. 7.7 Vertical ... g's •. ~ t, 4,3

Impact Speed - mph (km/h). 56.0 (88.2) Impact Angle ... deg , 0 • ~ 26.0 Exit Speed ~ mph (km/h).. N/A* Exi tAngl e ... deg . • • •• N/ A* Vehicle Damage Classification

TAD • • • • • . , • o. LFQ-5 SAE . o' • , • • • •• 10FLEW3

*Not available, vehicle did not exit barrier in field of view of overhead camera.

FI GURE 15 • SUMMARY OF TEST 2.

'~ .

FIGURE 16. TEST VEHICLE AND BARRIER BEFORE TEST 2.

32

!

FIGURE 17. TEST VEHICLE AFTER TEST 2.

33

'FIGURE 18. BARRIER AFTER TEST 2.

34

FIGURE 19. BARRIER JOINT AFTER TEST 2.

35

CONCLUSIONS

A precast concrete traffic barrier has been designed for work zones

which utilizes 15 ft (4.6 m) barrier segments. The barrier should be much

more portable than barriers currently in use in Texas which employ 30 ft

(9.1 m) segments. Barrier segments are attached with two C5 x 9 steel

splice channels and four 1-1/8 in. (2.86 cm) steel bolts. This joint

construction provides significant joint moment capacity without

significantly complicating barrier installation.

The barrier was successfully crash tested with a 4500 lb (2045 kg)

vehicle impacting at 25 degrees and 60 mph (96.6 km/h). The test vehicle

was smoothly redi rected, and vehi c 1 e acce 1 erati ons were wi thi n nati ona lly

accepted guidelines (~). No barrier segments were damaged during testing,

and only a few splice channels required repair or replacement. Temporary

barriers currently in use on Texas highways were damaged more severely when

tested under i denti ca 1 condi ti ons OJ. Therefore the precast concrete

traffic barrier described herein should be less costly to install and

maintain than similar barriers currently in use in Texas.

Although the barrier met impact performance standards for a permanent

barrier, it probably should not be used as such. For severe impacts, the

barrier can be expected to deflect 12 in. (30.5 cm) or more, and damage to

splice channels will occur.

36

APPENDIX A.

SEQUENTIAL PHOTOGRAPHS

37

0.000 sec

- 0.039 sec

0.091 sec

0.130 sec

FIGURE 20. SEQUENTIAL PHOTOGRAPHS FOR TEST 1.

38

0.180 sec

0.232 sec

0.310 sec

0.398 sec

FIGURE 20. SEQUENTIAL PHOTOGRAPHS FOR TEST 1 (continued). 39

· 0 ;000 S'E!C

0~038 sec

0.07.5 sec

0.128 sec

FIGURE 21. SEQUENTIAL PHOTOGRAPHS FOR TEST ,2. 40

'0- •• _ ..... ,' __ ••• ',<"" ••• ..,. -, ~ ..... / ~ "'~I __ 7 '.'" ." J,.,,' < ,

'.---.:.

O .. 11J3 sec

0.228 sec

0.306 sec

0.382 sec

FIGURE 21. SEQUENTIAL PHOTOGRAPHS FOR TEST 2 (continued).

41

APPENDIX B!

ACCELEROMETER TRACES AND

PLOTS OF ROLL, PITCH, AND YAW RATES

42

z o F-l

~ W ....J. . W U U c:c

o .' r---------=-------------------. o N

o c5 ...................................................................................................................... . ,....

o · . ~ ................ .. r

.. ': ................... : ....................... : ........................ ; ....................... . · . . . · . . . · . . . · . . . : : . : : · . . . · . . . · . . . · . . . · . . . · . . .

o ~ ; ~ ~ · ; : : : o : : : : ~ ........................ j ...................... j ........................ ~ ........................ : ...................... ..

· . . · . . • o· • · . . : : : · . . · . . · . · . · . · . · . · . · :: c5 ::

("t) ::

I~ ___ ~_---~:----~:~---~---~ 0.00 , 0" 10 0.20 0.30 0.4,0 0.50.

TIME (SECONDS)

FIGURE22~ ACCELERor~ETERTAACE FOR'TEST l-LONGITUDINAL DIRECTION.

43

d~------~--------~------~~------~-------, .--.

. 0 -g~--~~~~~~~~~**~~~~~~~~~~~ ........

en -0 .... ~ .....,,;

0.00 0.10 0.20· 0.30 0,40 0~50 .

TIME (SECONDS)

FIGURE 23. ACCELEROMETER TRACE FOR TEST 1 - LATERAL·DIRECTION.

44

o '~----~~--------~------~--------~------, o

N

o •.. , .... ............ . .. : ... , ............. -.- .... ,_ ........ _ ................ 0.·· .... _, ................................. . o :

.-.. r-en --

o .. ' q r--'

I ~------~~----~~~----~~----~~-----n~ 0.QO'0.1-0 .9 .. 20· <0.30. . 0.4p 0.50

TrME (SECONDS)

<FIGURE 24 •.. " ACCELEROMETER TRACE FOR TE?T 1 - VtRTICALDIRECTION.

45

a a .

'0 ::;j<.

o a . a c\i

a .0 ..

a ::t' I

0.4:0 TIME

FIGURE' 25. VEHI CtE ROLL YERSUS .1IME FOR TEST 1.

46

o. o . . a ::t'

o .0 .. ·0

;-.. C\J (f)

W ·.w

.a: 00 W o C)o4-~-----.~----~~~----~

.. '-' 0 00 0.80 1. 2

:c ... 0 • U o .. f- .

1-10 (LC\.i . I

.0 o .. o ::I' I

(SEC(JNOSJ

FIGURE 26. VEHICLE PITCH VERSUS TIME fOR TEST 1.

47

o '0 .. o .:::t'

o o . o J\J

(f)

w w teo DO W·-f--..,--.;.----,-----....,.....:...-----. b9J.O

"":70 . ·~o .. IT • . ~o .. (\J

. '.1

'0 o

0.80 1. 20 . (SECONDS)

FlGURE'27., VEHICLE YAW VERSUS TIME FOR TEST l. '. -" -~. .. ".

48

o .r-------:-------------.:~--------"-----,

o r--

z '0 ~.

~ ~ lLI 0 ..: ~ . i············· ......... ~ ........................ ~ ........................ ~ ........................ ~ ....................... .

u : : : :

cC ~ [ ~ ~ o . o C\J

I

: : : : · . . . · . . . · . . . · . . . · . . . · . . . · . . . : : : :

0.20 0.40' 0.60 0.80

TIME (SECOrfDS)

1.00

FIGURE28 . . ACCELERm4ETER TRACE FOR TEST 2- LONGITVDINAL DIRECTION.

49

z o H I-

~ LLL

. ...J LLI . U, U ex::

~r-------~--------~------~----------------~ b N

6 . <::> ................ . ............................................................................................... .

0 : •. 0

0 ~ . .. -, 0" r-

r ~ .... ···.························.·······················1· ............................................... .

b

I 0.00 0.40 0.60 0.80 .00

TIME (SECONDS)

. F['GURE 29.' ACCEl..EROr~ETER TRAcE FOR TEST 2 - LATERAL DIRECTION.

50

c:; N t

......................................................................................................................

............... ....... ........................ ........................ ........................ ....................... .

.............. ........ ........................ : ....................................................................... .

1).00

TIME (SECONDS)

FIGURE 30. ACCELEROt4ETER TRACE FOR TEST 2- VERTICAL DIRECTION.

51

o o · o ::i'

o ·0

· o C\J

.':'

o'~~----~--------~-----T~------~J

· o .:;j< ~I ..

. ~

o a:

FIGURE 3L VEHICLE ROLLVERS<US TIME FOR TEST 2 •

52

o Cl

· o ::I'

o o · o

ru

· 0

,.......0 (1)0

W~ wru 0::' b w 00 '-.JO

· 0 I::I' LJI l-..........

D-

f

FIGURE 32 • VEHICLE PITCH VERSUS TIME FOR 'TEST 2 .•

53

~------------------'------- - -

· . o· ru

TIME (SECONDS) 0.60 1.20 1.80 ~.oo 2.1.10

C;;~,-----~---------L--------L-------~

,-..

o o

(DC;; I..L!ru IJJI a: l:)

Wo 00 ....., .

o ::t'

3: 1

IT >-

o o · o ill

I

o o · o

ro 1

o o · o

o -I FIGURE 33. VEHICLE YAW VERSUS TIME FOR TEST 2.

54

REFERENCES

1. Hirsch, T. J. and Marquis, E. L., "Crash Test and Evaluation of a Pre­cast Concrete Median Barrier," Report No. TTI-2-10-75-223-1, Texas Transportation Institute, Texas A&M University, Oct. 1975.

2. Parks, D. M., Stoughton, R. L., Stoker,J. R., and Nordlin, E. F., "Vehicular Crash Tests of Unanchored Safety-Shaped Precast Concrete Median Barriers with Pinned End Connections," Report No. CA-DOT-TL-6624-1-76-52, Office of Transportation, Calif. DOT, Sacramento, Ca., Aug. 1976.

3. Stoughton, R. L., Parks, D. M., Stoker, J. R., and Nord1in, E. F., "Vehicular Impact Tests of Precast Concrete Median Barriers with Corru­gated Ends and Tensioned Cables,1I Report No. FHWA-CA-TL-78-13, Office of Transportation Laboratory, Calif. DOT, Sacramento, C~., June 1978.

4. Walker, K. C., IISimulation, DeSign, and Testing of a Portable Concrete Median Barrier," Master of Science Thesis, Texas A&M University, Civil Engineering Department, December 1979.

5. Bronstad, M. E., Calcote, L. R., and Kimball, C. Eo Jr., IIConcrete Median Barrier Research - Research Report," Report No. FHWA-RD-77-4, Southwest Research Institute, Mar. 1976.

6. "Reconvnended Procedures for Vehi cular Crash Test; ng of Hi ghway Appurte­nances, II Transportat; on Research Ci rcular No. 191, Transportati on Research Board, Feb~ 1978.

55