ASTM D2718-00(2006)
(Test Method)Standard Test Methods for Structural Panels in Planar Shear (Rolling Shear)
Standard Test Methods for Structural Panels in Planar Shear (Rolling Shear)
SCOPE
1.1 These test methods determine the shear properties of structural panels associated with shear distortion of the planes parallel to the edge planes of the panels. Both shear strength and modulus of rigidity may be determined. Primarily, the tests measure the planar shear (rolling shear) strength developed in the plane of the panel.
1.2 Structural panels in use include plywood, waferboard, oriented strand board, and composites of veneer and of wood-based layers.
1.3 Two test methods are included:
1.3.1 Test Method A Planar shear loaded by plates.
1.3.2 Test Method B Planar shear induced by five-point bending.
1.3.3 The choice of method will be dictated by the purpose of the test and equipment available.
1.3.4 Test Method A, Planar Shear Loaded by PlatesThis test method uses a rectangular panel section adhered between steel plates with protruding knife edges to create load at the panel faces. This test method has been used to develop shear properties of plywood and oriented strand board for the purpose of confirming design values. This test method does not produce pure shear, but the specimen length is prescribed so that the secondary stresses have a minimum effect. The method determines shear strength and modulus of rigidity.
1.3.5 Test Method B, Planar Shear Induced by Five-Point BendingPlanar shear stress is induced on the panel while loaded in bending using two continuous spans. This test method determines planar shear strength consistent with panel applications under transverse loading. This test method is able to determine shear strength at any moisture condition.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 The specimen having the form of a rectangular flat plate is bonded between steel plates beveled at opposite ends of the specimen to provide knife edges for loading the plate at the face bonded to the specimen. The knife edges project beyond the ends of the specimen. This test method is conducted by loading the knife edges in compression at a uniform rate while a suitable gage measures slip between the plates due to specimen deformation. Shear strength is computed from maximum load, and effective shear modulus for the specimen is determined from a plot of load versus slip.
1.5 Specimens are tested in a two-span continuous beam support configuration with line loads applied at midspan of each span as shown in . Induced shear stresses are consistent with those developed in conventional panel applications under transverse loading. Specimens may be tested in any moisture condition.Note 1Research that led to the development of the test method is available., Research on the test method's usefulness for determining elastic constants is also available.
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Designation: D2718 – 00 (Reapproved 2006)
Standard Test Methods for
Structural Panels in Planar Shear (Rolling Shear)
This standard is issued under the fixed designation D2718; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 These test methods determine the shear properties of
structural panels associated with shear distortion of the planes
2. Referenced Documents
parallel to the edge planes of the panels. Both shear strength
2.1 ASTM Standards:
and modulus of rigidity may be determined. Primarily, the tests
D2395 Test Methods for Specific Gravity of Wood and
measure the planar shear (rolling shear) strength developed in
Wood-Based Materials
the plane of the panel.
D4442 Test Methods for Direct Moisture Content Measure-
1.2 Structural panels in use include plywood, waferboard,
ment of Wood and Wood-Base Materials
oriented strand board, and composites of veneer and of
wood-based layers.
3. Significance and Use
1.3 Two test methods are included:
3.1 Planar shear (rolling shear) characteristics of structural
1.3.1 Test Method A—Planar shear loaded by plates.
panels determined by these test methods are essential for the
1.3.2 Test Method B—Planar shear induced by five-point
rigorous design of various glued wood-panel structural com-
bending.
ponents, such as box beams, folded plate roofs, and stressed
1.3.3 The choice of method will be dictated by the purpose
skin panels. Planar shear also may govern the design at low
of the test and equipment available.
span-depth ratios encountered in floors subjected to high
1.3.4 Test Method A, Planar Shear Loaded by Plates—This
concentrated loads, concrete forms at high pouring pressures,
test method uses a rectangular panel section adhered between
and bulk storage structures.
steel plates with protruding knife edges to create load at the
3.2 The modulus of rigidity determined fromTest MethodA
panel faces. This test method has been used to develop shear
is a composite of the entire specimen acting as a unit. For
properties of plywood and oriented strand board for the
plywood panels for which the ratio between the shear moduli
purpose of confirming design values.This test method does not
oftheplieswithgrainorientedparallelandperpendiculartothe
produce pure shear, but the specimen length is prescribed so
shear forces is known, the rolling shear modulus of the
that the secondary stresses have a minimum effect.The method
perpendicular plies can be calculated.
determines shear strength and modulus of rigidity.
3.3 Veneer produced by slicing or rotary peeling may
1.3.5 Test Method B, Planar Shear Induced by Five-Point
contain fine checks or separations parallel to the grain on the
Bending—Planar shear stress is induced on the panel while
knife side of the veneer that are produced as the knife is forced
loaded in bending using two continuous spans. This test
through the wood. These checks are termed “knife checks” to
method determines planar shear strength consistent with panel
distinguish them from occasional checks that may be formed
applications under transverse loading. This test method is able
on the opposite side of the veneer by forces at the compression
to determine shear strength at any moisture condition.
bar, and from checks caused by drying. Knife checks can have
1.4 This standard does not purport to address all of the
a significant effect on rolling shear properties in plywood
safety concerns, if any, associated with its use. It is the
panels and may be of significance in other veneer containing
responsibility of the user of this standard to establish appro-
panels.Test MethodArequires (when applicable) the testing of
This test method is under the jurisdiction of ASTM Committee D07 on Wood
and is the direct responsibility of Subcommittee D07.03 on Panel Products. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2006. Published October 2006. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
´1
approved in 1969. Last previous edition approved in 2000 as D2718 – 00 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D2718-00R06. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2718 – 00 (2006)
matching specimens having knife checks oriented both open the specimen due to growth or manufacturing features or from
and closed wherever possible (see Fig. 1). other causes shall be 6 in. (15 cm) wide by 18 in. (45 cm) long
3.4 To control or define other variables influencing rolling or larger as shown in Fig. 2. This size is recommended for
shear, these test methods require determination of moisture uniform material as well. However, smaller specimens of
content, specific gravity, and elapsed time-to-failure. Condi- uniform material may be used if these are not less than four
tioning of test material in controlled atmospheres, determina- times the thickness in width nor twelve times the thickness in
tion of depth of knife checks (when applicable), and determi- length.
nation of percent of wood and plywood glueline failure (when 6.2 From each sample of panels containing veneer, two
applicable) are recommended. matching specimens shall be cut. Knife edges of loading plates
for one specimen of each matching pair shall be oriented
4. Control of Moisture Content
perpendicular to one of the primary panel directions or for
4.1 The structural panel samples to be tested at specific
plywood to cause opening of knife checks during test as shown
moisture contents or equilibrium relative humidities shall be in Fig. 1(a). Knife edges of plates loading the other specimen
conditioned to approximately constant weight in controlled
shall be positioned perpendicular to one of the primary panel
atmospheric conditions before gluing to plates. For approxi- directions or for plywood to cause knife checks to close during
mating moisture conditions of structural panel used under dry test as shown in Fig. 1(b). Proper plywood orientation may be
conditions a relative humidity of 65 6 2 % at a temperature of determined from check depth specimens described in 16.3.It
68 6 6°F (20 6 3°C) is recommended. Specimens shall be may not be possible to test samples having two or more plies
tested without undue delay after the adhesive is cured. Testing
stressed in rolling shear in both “open” and “closed” orienta-
in similarly controlled atmospheres is recommended wherever tions if these plies are oriented in opposite directions causing
possible.
a“ checks open” failure regardless of direction of loading.
6.3 Specimen length and width shall be measured to the
Test Method A—Planar Shear Loaded by Plates
nearest 0.01 in. (0.25 mm) and thickness to the nearest 0.001
in. (0.025 mm). When applicable, the direction of knife checks
5. Scope
in plies having grain perpendicular to its length shall be
5.1 The specimen having the form of a rectangular flat plate
determined and the specimens marked for position of knife
is bonded between steel plates beveled at opposite ends of the
edges. At the time specimens are cut matching samples for
specimen to provide knife edges for loading the plate at the
determination of moisture content and specific gravity in
face bonded to the specimen. The knife edges project beyond
accordance with 16.1 and 16.2 shall be obtained. When
the ends of the specimen. This test method is conducted by
measurement of knife checks is included as discussed in 16.3,
loading the knife edges in compression at a uniform rate while
a sample for this measurement also may be cut at this time.
a suitable gage measures slip between the plates due to
specimen deformation. Shear strength is computed from maxi- 7. Loading
mum load, and effective shear modulus for the specimen is
7.1 Figs.1and2illustratethespecimenandsuitableloading
determined from a plot of load versus slip.
plates and blocks for loading the knife edges of the plates. The
6. Test Specimen
6.1 Specimen thickness shall be that of the material. Speci-
mensfrommaterialthatisexpectedtovarysignificantlywithin
NOTE—The “V” block is supported on a seat that provides rotation
about the axis perpendicular to the knife edge only.
Metric Equivalents
in. 6 18
mm 15 45
(a) Knife Checks Open
(b) Knife Checks Closed
FIG. 2 Planar (Rolling) Shear Test Using a Dial Gage for
FIG. 1 Orientation of Knife Checks in Plywood Measuring Plate Slip
D2718 – 00 (2006)
specimen shall be loaded by steel plates bonded to both faces 7.3 Both epoxy and polyvinyl adhesives have been found
of the specimen with an adhesive sufficiently rigid to preclude satisfactory for bonding steel plates to specimens. Minimum
contributionofadhesivecreeptomeasureddeformation.Width required surface preparation of steel plates consists of removal
of plates shall be that of the specimen. One end of each plate of residual adhesive. This can be accomplished most easily by
shall be provided with a knife edge projecting ⁄4 in. (6 mm) mild heating of the plate and any portion of the specimen
beyond the end of the specimen at one end and flush with the remaining from the previous test in an oven which weakens the
surface glued to the specimen. The other end of the plate shall bond to the steel sufficiently to permit peeling the remaining
be square and flush with the end of the specimen. Knife edges wood and adhesive from the plate. The residual adhesive may
of the two plates shall be at opposite ends of the specimen and be scraped off with a sharp-edged tool. Further degreasing and
shall be oriented to load the specimen in the desired direction cleaning has frequently been found necessary in addition to the
in relation to the knife checks. Planar shear properties of above to ensure adequate bond strength. Curing the adhesive at
structural panels should be determined in both directions. a slightly elevated temperature has also been helpful.
Plates for specimens 18 in. (45 cm) long shall be 1 in. (2.5 cm)
8. Measurement of Deformation
thick. The thickness of plates for shorter specimens may be
reduced proportionately. Loading of at least one V-block shall
8.1 Slip between the steel plates during load application
provide for uniform load distribution along the knife edge by
shall be measured to at least the nearest 0.0001 in. (0.002 mm)
loading through a pivot having its axis perpendicular to the
at no less than twelve and preferably more equally spaced
knife edge and centered along it. Pivots permitting rotation
increments of load to proportional limit from which a load-
about an axis parallel to the knife edge or spherical seats free
deformation curve shall be plotted. Slip can be measured with
to pivot in this manner shall not be used as they create unstable
a dial gage as illustrated in Figs. 2 and 3 or with appropriate
loadingwhichmaycauseviolentejectionofthespecimenfrom
automatic measuring and recording equipment. Gage geometry
the machine and hazard to operating personnel. The V-blocks
and position on the specimen shall be such as to minimize any
shall be vertically positioned in the machine, one above the
effects of unsymmetrical loading or deformation.
other, causing the forces applied to the specimen to act parallel
9. Calculation
to the axis of the machine. The specimen itself will be slightly
inclined when placed in the machine. A means of holding the
9.1 Shear stress shall be calculated as follows:
plates in an upright position after the specimen has sheared
f 5 P/ L·W (2)
~ !
v
apart is desirable as a complete separation of the specimen
permits the plates to be thrown out of the machine with
where:
attendant hazard to the operator.
f = shear stress, psi (N/mm),
v
7.2 Loadshallbeappliedcontinuouslythroughoutthetestat P = maximum or proportional limit load (force), lbf (N),
constant rate of cross-head motion to normally produce failure W = specimen width, in. (mm), and
L = specimen length, in. (mm).
in the range of 3 to 12 min elapsed time from beginning of
Maximum shear stress obtained from specimens having final
loading. For plywood, the approximate speed may be deter-
mined as follows: failure of the bond between the plate and the specimen shall be
regarded as defective and shall be clearly indicated in the
N 5 0.0075 ~(T 1 R(T ! (1)
| '
report of results.
where: 9.2 Effective modulus of rigidity for the specimen acting as
N = crosshead speed, in./min (cm/min), a unit shall be calculated as follows:
(T = total thickness of plies having grain parallel to
|
G 5 ~P/D!@t/~L·W!# (3)
direction of shear force, in. (cm),
R = 8 (assumed ratio of shear modulus of parallel plies
where:
to shear modulus of perpendicular plies), and
G = apparent modulus of rigidity for the entire speci-
(T = total thickness of plies having grain perpendicular
' men, psi (N/mm),
to the direction of shear force, in. (cm). t = specimen thickness, in. (mm),
7.2.1 Elapsed time from beginning of load application to P/D = slope of the force-deformation curve below propor-
tional limit load, lbf/in. (N/mm), and other notation
failure of each specimen shall be measured and recorded to the
nearest half minute. Machine speeds calculated by the above is as indicated in 9.1.
formula will normally produce failure in the range of 3 to 12 For plywood, modulus of rigidity of the cross plies may be
min elapsed time from the beginning of loading. Should calculated from that given above if the ratio of moduli of
elapsed time to failure fall greatly outside this range, machine rigidity and thickness of the parallel and perpendicular plies is
speed should be modified to obtain times within this range. known.
D2718 – 00 (2006)
FIG. 3 Planar (Rolling) Shear Specimen Ready for Testing
Test Method B—Planar Shear Induced by Five-Point
Bending
10. Scope
10.1 Specimens are tested in a two-span continuous beam
support configuration with line loads applied at midspan of
each span as shown in Fig. 4. Induced shear stresses are
consistent with those developed in conventional panel appli-
FIG. 4 Loading Configuration for the Five-Point Bending Method
cations under transverse loading. Specimens may be tested in
any moisture condition.
NOTE 1—Research that led to the development of the test method is NOTE 2—Specimen width may be modified for practical purpos
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