d

$J0 pase

Force (kips}

Pultruded Fiber-Glass Tube

Static Crush Test

Displacement (mm)

Displacement fin)

) 50 100 150 206 250 300
~ [ ~ T T T T T
Maxine ant “a :
t—— Comprassivu
: Farce, P variation, ¥ Avuraga Grusn
- | Force, Fa
rm ayy cant
— '
somm 2 wf 182mm tE.bint Bogma 114i)
! ia i | ! 1
2 4 6 & 10 12

400

16

Force [KN}


tw

First stage composite tube -- ]52-mm (6-in.) diameter with 3.2-mm (0.125-in.) wall
thickness

Average Crush Force, F, 85413 kN (19 +3 kips)
Maximum Compressive Force, P LI6kN (26 kips)

Second stage composite tube -- 152-mm (6-in.) diameter with 6.4-mm {0.2-in.) wali
thickness

Average Crush Force, F, 178+ 18kKN (40 +4 kips}
Maximum Compres Force, P 245 kN. (55 kipsi

The crush force characteristics for each of the three specimens do not exceed the
acceptable ranges by more than LO percent. In other words. each specimen shall not
exceed the following static energy dissipation properties:

First stage composite tube -- 152-mum {6-in.) diameter with 3.2-mm (0.125-in.) wall
thickness

Average Crush Force, F, 8S *22kN (19 +5 kips)
Maxiraum Compressive Force, ? 127 KN (28.5 kips)

Second stage composite tube -- 152-1r0m (6-in.} thameter with 6.4-mm (0.25-in.} wall
thickness

Average Crush Farce, F, 178+36KN (40+ 8 kips)
Maximum Compressive Force, > 267 KN (60 kips)

Page 3 of 4


Q

US.depantrrent £03 Severin St, SW
of Tarsportation wWastngten. OS 2056)
Federal Highway

Administration

Neuter 12, 1999

Refér to: HMHS-CC6GA,

Mr. King K. Mak

Research Engineer

Texas Transportation (nstitute
Callege Station, Texas 77843-3135

Dear Mr. Mak:

{n your October 12 letter, you requested the Federal Highway Administration's (FIIWA} review
and approval of the specifications for the energy-absorbing composite tubes used in the
Wyoming Box-Beam End Terminal (WYBET-350) that was accepted for use on the National
Highway System on August 19, 1999. These specilications were developed hy the Texas

Vransportation Institute for the Wyoming Depzrtment of Transportation, but can be used by any
Department of Transportation that uses box-beam guardrail and the WYBET-350 terminal.

The specifications, which are enclosed, appear to satisfy the need for quality control of the
composite tubes to ensure adequate erash perfurance of the WYBET-380, and we fin chem
acceptable.

Sincerely yours,

Mgll . Mee

Dwight A. Horne
Director, Office of Highway Safety Intrasteucture

Enclosure


SPECIFICATIONS AND TEST PROCEDURE FOR COMPOSITE TUBE

This specification outlines the material properties and required energy dissipatian properties for the
fiberglass/epoxy composite tubes used in the Wyoming box-beam end terminal (WYBET). Two
slages of energy dissipation are employed in the design: the first stage consists of a 152-mm (6-in.)
diameter composite tube with a 3.2-mm (0.125-in,) wall thickness, and the second stage a 152-mm
(6-1n.) diameter composite tube with a 6.4-nm (0.25-in.) wall thickness.

senera! Specifications

° The fiberglass/epoxy composite tube shall be manufactured using the “pultrusion" process
and consists of a glass fiber reinforced resin matrix with a glass resin ratio of approximately
50 percent. The resin shall consist of isophthallic polyester and glass reinforcement shall
include the following three varieties:

a A surface mat shall be used on all exterior surfaces for chemical resistance and
camtainment of other reinforcement fibers.

b. Continuous glass strand rovings shall be used internally for jongitudinal strength.
c. Continuous strand mats shall be used internally for transverse strength.
. The composite material shall exhibit the following mininyum mechanical propertivs;
a Ultimate Tensife Strength:
(Longitudinal Coupon) 205 Mpa (30,000 psi)
{Transverse Coupon) 48 Mpa ( 7,000 psi)
(Full Section in Bending) 138 Mpa (20,000 psi)
b. Ultimate Compressive Strength:
{Longitudina] Coupon) 205 Mpa (30,000 psi)
{Transverse Coupon) 102 Mpa (15,000 psi)
(Full Section in Bending) 138 Mpa (20,000 psi)
c. Ultimate Shear Strength 31 Mpa ( 4,500 psi}
d. Ultimate Breaking Strength 205 Mpa (30,000 psi}
a Modulus of Elasticity
{Full Beam Section in Bending) 17237 Mpa (2.5 x 10° psi)
f. Barcol Hardness 50

Page lof 4


Crash Force Characteristics
* ‘The energy dissipation properties of the composite tube shall be evaluated using static
compressive testing. The composite tubes shail have the foltowing static energy dissipation

properties:

First stage composite tube -- 152-mm (6-in.} diameter with 3.2-mm (0), 125-in.} wall thickness

Average Crush Foree, F, 85+I3kN (19+ 3kips)

Maximum Compressive Force, P TH6kKN {26 kips)}
Second stage composite tube -- 152-mm (6-in.} diameter with 6.4-mmi (0.25-in.) wall
thickness

Average Crush Fore, F, 178+ 18KN (4044 kips}

Maximum Compressive Force, P 245 kN {55 kips)

Detinjtions of the average crush force, F,, and maximum compressive force, P. are ilustrareel
in the following figure. The average crush force shall be determined based on crush forces
from 152 mm to 355 mm (6.0 in. to 14.0 in.) of crush. The maximum compressive force
shal] be determined between 90 mm to 152 mm (3.5 in, to 6.0 in} of crush.

Acceptance/Rejection Criteria

. The acceptance/rejection criteria will be ‘xased on the crush force characteristics, i.e., average
crush force, F,, and maximum compress: ve force, P. The properties outlined in the “General
Specifications” are provided for information purposes and are not considered in the
acceptance/rejection criteria

« A minimum of three (3) static compressive tests should be conducted at an independent
testing laboratory. The three samples shall be randomly selected, onc each from the
beginning, middle and end of the production mun being evaluated, Bach test specimen shall
be 610 mm (24 in.) long and a 100 mm (4 in.) long tulip shape shall be cut into one end of
the test spectmen. End caps shall be used with the specimen on both ends

The test specimen shall be crushed stancally at a rate of 50 mm {2 in.} per minute and the
total crush length or displacement shail be av Jess than 355 mm (14.0 in.)

e The batch is considered acceptable if th: following condiuons are met:

lL. The average crush force charuteristics for the three specimens are within Lhe
acceptable ranges as specified above and repeated helow:

Pave 2 of 4