ASTM D2718 - 24

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Designation: D2718 −24

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

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, but are not limited to,

structural plywood, oriented strand board (OSB), and compos-

ites 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 Plates—This

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

Bending—Planar 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.

1.4 The values stated in inch-pound units are to be regarded

as standard. When there are values given in parentheses, these

are mathematical conversions to SI units that are provided for

information only and are not considered standard.

1.5 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 appro-

priate safety, health, and environmental practices and deter-

mine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accor-

dance with internationally recognized principles on standard-

ization established in the Decision on Principles for the

Development of International Standards, Guides and Recom-

mendations issued by the World Trade Organization Technical

Barriers to Trade (TBT) Committee.

2. Referenced Documents

2.1 ASTM Standards:

D2395 Test Methods for Density and Speciﬁc Gravity (Rela-

tive Density) of Wood and Wood-Based Materials

D4442 Test Methods for Direct Moisture Content Measure-

ment of Wood and Wood-Based Materials

3. Signiﬁcance and Use

3.1 Planar shear (rolling shear) characteristics of structural

panels determined by these test methods are essential for the

rigorous design of various glued wood-panel structural

components, such as box beams, folded plate roofs, and

stressed skin panels. Planar shear also may govern the design

at low span-depth ratios encountered in ﬂoors subjected to high

concentrated loads, concrete forms at high pouring pressures,

and bulk storage structures.

3.2 The modulus of rigidity determined from Test Method A

is a composite of the entire specimen acting as a unit. For

plywood panels for which the ratio between the shear moduli

of the plies with grain oriented parallel and perpendicular to the

shear forces is known, the rolling shear modulus of the

perpendicular plies can be calculated.

3.3 Veneer produced by slicing or rotary peeling may

contain ﬁne checks or separations parallel to the grain on the

knife side of the veneer that are produced as the knife is forced

through the wood. These checks are termed “knife checks” to

distinguish them from occasional checks that may be formed

on the opposite side of the veneer by forces at the compression

These test methods are under the jurisdiction of ASTM Committee D07 on

Wood and is the direct responsibility of Subcommittee D07.03 on Panel Products.

Current edition approved Feb. 15, 2024. Published February 2024. Originally

approved in 1969. Last previous edition approved in 2018 as D2718 – 18. DOI:

10.1520/D2718-24.

For referenced ASTM standards, visit the ASTM website, www.astm.org, or

contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM

Standards volume information, refer to the standard’s Document Summary page on

the ASTM website.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the

Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

bar, and from checks caused by drying. Knife checks can have

a signiﬁcant effect on rolling shear properties in plywood

panels and may be of signiﬁcance in other veneer containing

panels. Test Method A requires (when applicable) the testing of

matching specimens having knife checks oriented both open

and closed wherever possible (see Fig. 1).

3.4 To control or deﬁne other variables inﬂuencing rolling

shear, these test methods require determination of moisture

content, speciﬁc gravity, and elapsed time-to-failure. Condi-

tioning of test material in controlled atmospheres, determina-

tion of depth of knife checks (when applicable), and determi-

nation of percent of wood and plywood glueline failure (when

applicable) are recommended.

4. Control of Moisture Content

4.1 The structural panel samples to be tested at speciﬁc

moisture contents or equilibrium relative humidities shall be

conditioned to approximately constant weight in controlled

atmospheric conditions before gluing to plates. For approxi-

mating moisture conditions of structural panel used under dry

conditions a relative humidity of 65 % 62 % at a temperature

of 68 °F 66 °F (20 °C 63 °C) is recommended. When using

Test Method A, specimens shall be tested without undue delay

after the adhesive is cured. Testing in similarly controlled

atmospheres is recommended wherever possible.

Test Method A—Planar Shear Loaded by Plates

5. Scope

5.1 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 gauge measures slip between the plates due to

specimen deformation. Shear strength is computed from maxi-

mum load, and effective shear modulus for the specimen is

determined from a plot of load versus slip.

6. Test Specimen

6.1 Specimen thickness shall be that of the material. Speci-

mens from material that is expected to vary signiﬁcantly within

the specimen due to growth or manufacturing features or from

other causes shall be 6 in. (152 mm) wide by 18 in. (457 mm)

long or larger as shown in Fig. 2. This size is recommended for

uniform material as well. However, smaller specimens of

uniform material may be used if these are not less than four

times the thickness in width nor twelve times the thickness in

length.

6.2 From each sample of panels containing veneer, two

matching specimens shall be cut. Knife edges of loading plates

for one specimen of each matching pair shall be oriented

perpendicular to one of the primary panel directions or for

plywood to cause opening of knife checks during test as shown

in Fig. 1(a). Knife edges of plates loading the other specimen

shall be positioned perpendicular to one of the primary panel

directions or for plywood to cause knife checks to close during

test as shown in Fig. 1(b). Proper plywood orientation may be

determined from check depth specimens described in 16.3. It

may not be possible to test samples having two or more plies

stressed in rolling shear in both “open” and “closed” orienta-

tions if these plies are oriented in opposite directions causing a

“checks open” failure regardless of direction of loading.

6.3 Specimen length and width shall be measured to the

nearest 0.01 in. (0.2 mm) and thickness to the nearest 0.001 in.

(0.02 mm). When applicable, the direction of knife checks in

plies having grain perpendicular to its length shall be deter-

mined and the specimens marked for position of knife edges.

(a) Knife Checks Open

(b) Knife Checks Closed

FIG. 1 Orientation of Knife Checks in Plywood

NOTE 1—The “V” block is supported on a seat that provides rotation

about the axis perpendicular to the knife edge only.

SI Equivalents

in. 6 18

mm 152 457

FIG. 2 Planar (Rolling) Shear Test Using a Dial Gauge for

Measuring Plate Slip

D2718 − 24

At the time specimens are cut matching samples for determi-

nation of moisture content and speciﬁc gravity in accordance

with 16.1 and 16.2 shall be obtained. When measurement of

knife checks is included as discussed in 16.3, a sample for this

measurement also may be cut at this time.

7. Loading

7.1 Figs. 1 and 2 illustrate the specimen and suitable loading

plates and blocks for loading the knife edges of the plates. The

specimen shall be loaded by steel plates bonded to both faces

of the specimen with an adhesive sufficiently rigid to preclude

contribution of adhesive creep to measured deformation. Width

of plates shall be that of the specimen. One end of each plate

shall be provided with a knife edge projecting

⁄

in. (6 mm)

beyond the end of the specimen at one end and ﬂush with the

surface glued to the specimen. The other end of the plate shall

be square and ﬂush with the end of the specimen. Knife edges

of the two plates shall be at opposite ends of the specimen and

shall be oriented to load the specimen in the desired direction

in relation to the knife checks. Planar shear properties of

structural panels should be determined in both directions.

Plates for specimens 18 in. (457 mm) long shall be 1 in.

(25.4 mm) thick. The thickness of plates for shorter specimens

may be reduced proportionately. Loading of at least one

V-block shall provide for uniform load distribution along the

knife edge by loading through a pivot having its axis perpen-

dicular to the knife edge and centered along it. Pivots permit-

ting rotation about an axis parallel to the knife edge or

spherical seats free to pivot in this manner shall not be used as

they create unstable loading which may cause violent ejection

of the specimen from the machine and hazard to operating

personnel. The V-blocks shall be vertically positioned in the

machine, one above the other, causing the forces applied to the

specimen to act parallel to the axis of the machine. The

specimen itself will be slightly inclined when placed in the

machine. A means of holding the plates in an upright position

after the specimen has sheared apart is desirable as a complete

separation of the specimen permits the plates to be thrown out

of the machine with attendant hazard to the operator.

7.2 Load shall be applied continuously throughout the test at

constant rate of cross-head motion to normally produce failure

in the range of 3 min to 12 min elapsed time from beginning of

loading. For plywood, the approximate speed may be deter-

mined as follows:

N50.0075

(

(1)

where:

N= crosshead speed, in./min (mm/min),

∑T

= total thickness of plies having grain parallel to

direction of shear force, in. (mm),

R= 8 (assumed ratio of shear modulus of parallel plies to

shear modulus of perpendicular plies), and

∑T

= total thickness of plies having grain perpendicular to

the direction of shear force, in. (mm).

7.2.1 Elapsed time from beginning of load application to

failure of each specimen shall be measured and recorded to the

nearest half minute. Machine speeds calculated by the above

formula will normally produce failure in the range of 3 min to

12 min elapsed time from the beginning of loading. Should

elapsed time to failure fall greatly outside this range, machine

speed should be modiﬁed to obtain times within this range.

7.3 Both epoxy and polyvinyl adhesives have been found

satisfactory for bonding steel plates to specimens. Minimum

required surface preparation of steel plates consists of removal

of residual adhesive. This can be accomplished most easily by

mild heating of the plate and any portion of the specimen

remaining from the previous test in an oven which weakens the

bond to the steel sufficiently to permit peeling the remaining

wood and adhesive from the plate. The residual adhesive may

be scraped off with a sharp-edged tool. Further degreasing and

cleaning has frequently been found necessary in addition to the

above to ensure adequate bond strength. Curing the adhesive at

a slightly elevated temperature has also been helpful.

8. Measurement of Deformation

8.1 Slip between the steel plates during load application

shall be measured to at least the nearest 0.0001 in. (0.002 mm)

at no less than twelve and preferably more equally spaced

increments of load to proportional limit from which a load-

deformation curve shall be plotted. Slip can be measured with

a dial gauge as illustrated in Figs. 2 and 3 or with appropriate

automatic measuring and recording equipment. Gauge geom-

etry and position on the specimen shall be such as to minimize

any effects of unsymmetrical loading or deformation.

9. Calculation

9.1 Shear stress shall be calculated as follows:

5P⁄

L·W

(2)

where:

= shear stress, psi (N/mm

P= maximum or proportional limit load (force), lbf (N),

W= specimen width, in. (mm), and

L= specimen length, in. (mm).

Maximum shear stress obtained from specimens having ﬁnal

failure of the bond between the plate and the specimen shall be

regarded as defective and shall be clearly indicated in the

report of results.

9.2 Effective modulus of rigidity for the specimen acting as

a unit shall be calculated as follows:

P/∆

L·W

(3)

where:

G= apparent modulus of rigidity for the entire specimen,

psi (N/mm

t= specimen thickness, in. (mm),

P/∆= slope of the force-deformation curve below propor-

tional limit load, lbf/in. (N/mm), and other notation is

as indicated in 9.1.

For plywood, modulus of rigidity of the cross plies may be

calculated from that given above if the ratio of moduli of

rigidity and thickness of the parallel and perpendicular plies is

known.

D2718 − 24

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摘要：

ASTM D2718 - 24 是一项国际标准，专门用于测定木基结构板材在平面内剪切性能的试验方法，最新修订于2024年发布。该标准适用于胶合板、定向刨花板（OSB）及其他结构用复合板材，通过特定加载装置评估材料在剪切荷载下的强度与刚度表现，为建筑结构设计、工程认证及质量控制提供关键依据。标准详细规定了试样制备、试验设备要求、加载速度及数据处理流程，确保测试结果在不同实验室间的可重复性与可比性。对于从事木结构工程设计、板材生产或质量检测的专业人员而言，掌握ASTM D2718 - 24的核心内容

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