ASTM D2719-89(2001)
(Test Method)Standard Test Methods for Structural Panels in Shear Through-the-Thickness
Standard Test Methods for Structural Panels in Shear Through-the-Thickness
SCOPE
1.1 These test methods determine the shear through-the-thickness properties of structural panels associated with shear distortion of the major axis. Structural panels in use include plywood, wafer board, oriented strand board, and composites of veneer and of wood based layers. Three test methods are included which differ somewhat in their application: Test MethodSectionA.Small Panel Shear Test5B.Large Panel Shear Test6C.Two Rail Shear Test7
The choice of test method will be determined in part by the purpose of the tests, characteristics of test material, and equipment availability. In general, Test Method B or C for large specimens is preferred when equipment, amount of test material, and experimental plan permit.
1.1.1 Test Method A: Small Panel Shear Test—This test method is suitable for testing small samples of uniform material including investigations of the effects of grain direction or orientation and of many raw materials and manufacturing process variables which influence shear properties uniformly throughout the specimen. The test method is unsuited for determining effects of grade and manufacturing features such as density variations, knots, and core gaps within the specimen.
1.1.2 Test Method B: Large Panel Shear Test—This test method is regarded as giving the most accurate modulus of rigidity and is therefore recommended for elastic tests of materials to be used in stress analysis studies of test structures. This test method also yields excellent shear strength values for clear material. However, in spite of the large size of the specimen, failures generally occur only in narrow zones at the perimeter of the test area. This characteristic, a result of the heavy perimeter framing, causes this test method to be generally unsuited for determining grade and manufacturing effects such as density variations, core gaps, and knots that are not uniformly distributed throughout the panel. Generally, only in cases where effects of these factors under conditions of heavy perimeter framing are desired, should the test method be applied.
1.1.3 Test Method C: Two-Rail Shear Test— This test method is applicable to a wide variety of materials and problems. The specimen fabrication and test procedures are somewhat simpler than in Test Methods A and B. The specimen is free to shear parallel to its 24-in.(610-mm) length dimension anywhere within the 8-in. (203-mm) width between rails. Thus, the test method is well suited for determining grade and manufacturing effects such as core gaps and knots occupying and affecting small areas. The test method is not so ideally suited for determination of modulus of rigidity, but when adjusted for strain distribution effects, values approximating those obtained by Test Method B result. The test method simulates effects of heavy framing when expected planes of weakness are oriented perpendicular to rails and no framing at all when parallel to rails.
1.2 Significant differences, moderate to small in magnitude, among the three test methods have been found to exist when these test methods are applied to plywood of clear straight-grained veneers. Therefore, when comparisons are made among test results, it is recommended that the same test method be used throughout.
1.3 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.
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Designation: D 2719 – 89 (Reapproved 2001)
Standard Test Methods for
Structural Panels in Shear Through-the-Thickness
This standard is issued under the fixed designation D 2719; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope method is applicable to a wide variety of materials and
problems. The specimen fabrication and test procedures are
1.1 These test methods determine the shear through-the-
somewhat simpler than in Test Methods A and B. The specimen
thickness properties of structural panels associated with shear
is free to shear parallel to its 24-in.(610-mm) length dimension
distortion of the major axis. Structural panels in use include
anywhere within the 8-in. (203-mm) width between rails. Thus,
plywood, wafer board, oriented strand board, and composites
the test method is well suited for determining grade and
of veneer and of wood based layers. Three test methods are
manufacturing effects such as core gaps and knots occupying
included which differ somewhat in their application:
and affecting small areas. The test method is not so ideally
Test Method Section
suited for determination of modulus of rigidity, but when
A. Small Panel Shear Test 5
B. Large Panel Shear Test 6
adjusted for strain distribution effects, values approximating
C. Two Rail Shear Test 7
those obtained by Test Method B result. The test method
The choice of test method will be determined in part by the
simulates effects of heavy framing when expected planes of
purpose of the tests, characteristics of test material, and weakness are oriented perpendicular to rails and no framing at
equipment availability. In general, Test Method B or C for large
all when parallel to rails.
specimens is preferred when equipment, amount of test mate- 1.2 Significant differences, moderate to small in magnitude,
rial, and experimental plan permit.
among the three test methods have been found to exist when
1.1.1 Test Method A: Small Panel Shear Test—This test these test methods are applied to plywood of clear straight-
method is suitable for testing small samples of uniform
grained veneers. Therefore, when comparisons are made
material including investigations of the effects of grain direc- among test results, it is recommended that the same test
tion or orientation and of many raw materials and manufactur-
method be used throughout.
ing process variables which influence shear properties uni- 1.3 This standard does not purport to address all of the
formly throughout the specimen. The test method is unsuited
safety concerns, if any, associated with its use. It is the
for determining effects of grade and manufacturing features responsibility of the user of this standard to establish appro-
such as density variations, knots, and core gaps within the
priate safety and health practices and determine the applica-
specimen. bility of regulatory limitations prior to use.
1.1.2 Test Method B: Large Panel Shear Test—This test
2. Referenced Documents
method is regarded as giving the most accurate modulus of
rigidity and is therefore recommended for elastic tests of 2.1 ASTM Standards:
materials to be used in stress analysis studies of test structures.
D 2395 Test Methods for Specific Gravity of Wood and
This test method also yields excellent shear strength values for Wood-Base Materials
clear material. However, in spite of the large size of the D 4442 Test Methods for Direct Moisture Content Measure-
specimen, failures generally occur only in narrow zones at the ment of Wood and Wood–Base Materials
perimeter of the test area. This characteristic, a result of the
3. Significance and Use
heavy perimeter framing, causes this test method to be gener-
ally unsuited for determining grade and manufacturing effects 3.1 The strength and modulus of rigidity of structural panels
in shear through-the-thickness obtained by these test methods
such as density variations, core gaps, and knots that are not
uniformly distributed throughout the panel. Generally, only in are required for the rigorous design of many lumber-panel
structural components such as trusses with panel gussets, box
cases where effects of these factors under conditions of heavy
perimeter framing are desired, should the test method be beams, folded plate roofs, and space plane structures, as well as
floor and roof diaphragms, and shear walls. These properties
applied.
1.1.3 Test Method C: Two-Rail Shear Test—This test are of secondary importance in typical roof deck and sheathing
applications, and in crates and shipping containers.
3.2 Veneer produced by slicing or rotary peeling may
These test methods are under the jurisdiction of ASTM Committee D7 on Wood
and are the direct responsibility of Subcommittee D07.03 on Panel Products.
Current edition approved Aug. 25, 1989. Published October 1989. Originally
1 2
published as D 2719 – 69 T. Last previous edition D 2719 – 76 (1981)e . Annual Book of ASTM Standards, Vol 04.10.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2719
contain fine checks or separations parallel to the grain on the times specimen thickness, and block width and thickness shall
knife side of the veneer that are produced as the knife is forced not be less than 5 and 2.5 times specimen thickness, respec-
through the wood. These checks are termed “knife checks” to tively. Reinforcing blocks shall be of birch, maple, or other
distinguish them from occasional checks that may be formed wood of similar strength and rigidity. The average of specimen
on the opposite side of the veneer by forces at the compression thickness at two diagonally opposite corners and the dimen-
bar, and from checks caused by drying. Average depth of knife sions of the shear area inside the reinforcing blocks shall be
checks has been found to strongly influence shear properties in determined and recorded to the nearest 0.3 % or 0.001 in.
plywood panels and may be of significance in veneer incorpo- (0.025 mm), whichever is larger.
rated in composite panels. Measurement of depth of knife
5.3 Loading—Apply the load by special steel loading
checks is recommended in these test methods.
blocks which articulate with the rollers and pins attached to the
3.3 To control or define other variables influencing shear
test specimen. The angle between faces of the loading block
properties, these test methods require determination of mois-
shall be 90° and between each face and the base the angle shall
ture content and elapsed time to failure. The conditioning of
be 45°. A spherical bearing block, preferably of the suspended,
test material in controlled atmosphere and determination of
self-aligning type, shall be employed in the loading system.
specific gravity are recommended.
Apply the load continuously throughout the test with a uniform
motion of the movable head of the testing machine equal to
4. Control of Moisture Content
0.0025 in./in. of test area diagonal length/min (mm/mm·min)
4.1 Structural panel samples to be tested at a specific corresponding to a shear strain rate of 0.005 in./in.·min
temperature/relative humidity shall be conditioned to approxi-
(mm/mm·min) within a permissible variation of 625 %.
mate constant weight in controlled atmospheric conditions
5.3.1 Load each of the eight reinforcing blocks through
before gluing wood rails. Conditioning of fabricated specimens
roller brackets clamped to the reinforcing block across its
at the same temperature and relative humidity shall be contin-
width or attached by other means and applying a compressive
ued until the adhesive has cured sufficiently to ensure adequate
force to the end of the reinforcing block through a surface
2 2
bond strength. For approximating moisture conditions of struc-
contact area of at least 0.75 in. (484 mm ). These bearing
tural panels used under dry conditions, a relative humidity of
surfaces shall be firmly seated against the ends of their
65 6 2 % at a temperature of 68 6 6°F (20 6 3°C) is
respective reinforcing blocks during assembly. Rollers shall be
recommended.
centered at the inner edge of the reinforcing block and 1.25 in.
(31.8 mm) from the loaded end of the reinforcing block.
5. Test Method A—Small Panel Shear Test
Moderate clamping pressure holding brackets to the reinforc-
5.1 Summary—A specimen having a square shear area
ing blocks applied perpendicular to the plane of the panel is
bounded on each side by solid wood blocks glued to both sides
permitted but shall not be excessive.
of the specimen is loaded in compression along one diagonal in
5.3.1.1 Fig. 2 illustrates detail of suitable roller brackets and
a conventional testing machine. Forces are applied to the
their method of attachment to the reinforcing blocks with small
glued-on blocks through a roller bracket assembly which
wood wedges. Fig. 3 shows a specimen loaded by means of
causes the resultant forces to act collinearly with the edge of
roller brackets, and Fig. 4 gives working drawings for these
the shear test area. This loading method most nearly produces
brackets. Brackets are clamped across the width of the rein-
uniform pure shear. Shear strength is determined from maxi-
forcing blocks by driving small wedges between a projection
mum load, and modulus of rigidity may be calculated from
on the bracket and the reinforcing block. The clamping bolt is
measurements of compression strain along the compression
used to apply moderate clamping pressure perpendicular to the
diagonal of the specimen.
plane of the specimen. Other bracket devices conforming to the
5.2 Test Specimen—Dimensions shown in Fig. 1 of the
requirements of 5.3.1 are permitted but shall be described in
panel specimen and reinforcing blocks depend upon panel
detail in the report of test results.
thickness. Distance between blocks, L, shall not exceed 20
5.3.1.2 Measure the elapsed time from initiation of loading
to the maximum load and record to the nearest ⁄2 min.
5.4 Measurement of Deformation—When deformation data
are desired for calculation of elastic properties, strain-
measuring devices having minimum gage length of 1 in. (25
mm) shall be attached to both sides of the specimen and shall
measure compression strain of the vertical (or compression)
diagonal, the gages being centered at its midpoint on each side.
A larger gage length is preferred but shall not exceed one half
the length of the diagonal. Instruments and the accuracy of
their recording shall be to the nearest 0.0001 in. (0.0025 mm)
or 2 % of expected ultimate strain, whichever is smaller. Strain
readings of the two gages shall be averaged for computation of
Metric Equivalents
elastic properties.
1 1
in. ⁄16 ⁄2
mm 1.6 12.7
5.5 Calculation:
FIG. 1 Small Panel Shear Specimen and Dimensions 5.5.1 Calculate the maximum shear stress or shear stress at
D 2719
FIG. 2 Small Panel Shear Specimen with Roller Brackets
the proportional limit as follows: 6.2 Test Specimens—Fig. 5 gives detail of the specimen as
well as a suitable loading method. Shear area of the specimen
T 5 0.707 ~P/Lt! (1)
shall not be less than 24 in. (610 mm) on a side, and shall not
where:
exceed 48 times total specimen thickness. When structural
T = shear stress, psi (N/m ),
1 1
panels less than ⁄2 in. (12.7 mm) thick or less than ⁄48 the side
P = load (force), lbf (N),
of the shear area is to be tested for shear strength, two or more
L = length of side of shear area, in. (m), (Fig. 1), and
thicknesses of structural panels may be glued together (major
t = thickness of shear specimen, in. (m).
axis parallel) to form a test panel of the required thickness.
5.5.2 Calculate modulus of rigidity from deformation data
Specimens to be tested for modulus of rigidity only may be of
as follows:
lesser thickness provided sufficient data can be obtained before
G 5 0.3536 ~P/D!@L /~L · t! (2)
the test is halted due to initiation of buckling. Lumber rails
having a length equal to the side of the shear area, thickness not
where:
1 1
less than ⁄25 and width not less than ⁄6 the length of one side
G = modulus of rigidity, psi (N/m ),
P/D = slope of force/deformation curve, lbf/in. (N/m), of the shear area shall be glued to the structural panels with a
L = gage length, in. (m), and
rigid adhesive. Wider rails may be necessary to prevent rolling
t = thickness of shear specimen, in. (m).
shear failures between thick or high-strength panels and the
rails. Corners of the structural panels specimen shall be
6. Test Method B—Large Panel Shear Test
notched with the inside corner of the notch provided with a
6.1 Summary—A specimen having a square shear area is
fillet of ⁄2-in. (12.7-mm) radius as shown in Fig. 5. Ends of the
loaded through heavy lumber rails glued to both sides of the
rails to which loads are applied shall form a flat plane
specimen at all four edges of the shear area. Loading by a
perpendicular to the plane of the specimen. Use of a jig to
system of pins and yokes applies forces to the rails having a
position rails accurately at the time of assembly or a light saw
resultant acting at the inside edge of the shear area. Maximum
cut across the end of both rails after assembly may be helpful.
shear strength is determined from maximum load and modulus
of rigidity from elongation of the tension diagonal and corre- Depending upon the method of deformation measurement,
sponding loads. holes for gage pins may be needed as illustrated in Fig. 5.
D 2719
FIG. 3 Small Panel Shear Specimen with Loading and Strain-Measuring Apparatus Placed in Testing Machine
Average specimen thickness shall be determined from mea- 6.3.2 Load the specimen by constant motion of the movable
surements at each corner of the shear area to an accuracy of crosshead throughout the test such that the shear area of the
0.001 in. (0.025 mm). Width and length of the shear area shall specimen is strained at the rate of 0.005 in./in. (mm/mm)/min
be measured to an accuracy of 0.01 in. (0.25 mm). shear strain6 25 %. Head speed may be calculated by the
6.3 Loading—Load the specimen loading jig assembly in following equation:
tension. The resultant of forces applied to a pair of rails shall
n 5 ZL/ 2 (3)
=
be a single force acting at, and parallel to, the edge of the shear
area. If the ends of rails are compression loaded, the jigs shall where:
restrain any tendency for the rails to deflect laterally from the n = crosshead speed, in./min (mm/min),
L = length of side of shear area, in. (mm), and
plane of the
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