ASTM D2719-89(2007)
(Test Method)Standard Test Methods for Structural Panels in Shear Through-the-Thickness
Standard Test Methods for Structural Panels in Shear Through-the-Thickness
SIGNIFICANCE AND USE
The strength and modulus of rigidity of structural panels in shear through-the-thickness obtained by these test methods are required for the rigorous design of many lumber-panel structural components such as trusses with panel gussets, box beams, folded plate roofs, and space plane structures, as well as floor and roof diaphragms, and shear walls. These properties are of secondary importance in typical roof deck and sheathing applications, and in crates and shipping containers.
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 bar, and from checks caused by drying. Average depth of knife checks has been found to strongly influence shear properties in plywood panels and may be of significance in veneer incorporated in composite panels. Measurement of depth of knife checks is recommended in these test methods.
To control or define other variables influencing shear properties, these test methods require determination of moisture content and elapsed time to failure. The conditioning of test material in controlled atmosphere and determination of specific gravity are recommended.
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 ...
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Designation: D2719 − 89 (Reapproved2007)
Standard Test Methods for
Structural Panels in Shear Through-the-Thickness
This standard is issued under the fixed designation D2719; 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 cases where effects of these factors under conditions of heavy
perimeter framing are desired, should the test method be
1.1 These test methods determine the shear through-the-
applied.
thickness properties of structural panels associated with shear
1.1.3 Test Method C: Two-Rail Shear Test— This test
distortion of the major axis. Structural panels in use include
method is applicable to a wide variety of materials and
plywood, wafer board, oriented strand board, and composites
problems. The specimen fabrication and test procedures are
of veneer and of wood based layers. Three test methods are
somewhatsimplerthaninTestMethodsAandB.Thespecimen
included which differ somewhat in their application:
is free to shear parallel to its 24-in.(610-mm) length dimension
Test Method Section
anywherewithinthe8-in.(203-mm)widthbetweenrails.Thus,
A. Small Panel Shear Test
B. Large Panel Shear Test 6
the test method is well suited for determining grade and
C. Two Rail Shear Test 7
manufacturing effects such as core gaps and knots occupying
The choice of test method will be determined in part by the
and affecting small areas. The test method is not so ideally
purpose of the tests, characteristics of test material, and
suited for determination of modulus of rigidity, but when
equipmentavailability.Ingeneral,TestMethodBorCforlarge
adjusted for strain distribution effects, values approximating
specimens is preferred when equipment, amount of test
those obtained by Test Method B result. The test method
material, and experimental plan permit.
simulates effects of heavy framing when expected planes of
1.1.1 Test Method A: Small Panel Shear Test—This test
weakness are oriented perpendicular to rails and no framing at
method is suitable for testing small samples of uniform
all when parallel to rails.
material including investigations of the effects of grain direc-
1.2 Significant differences, moderate to small in magnitude,
tion or orientation and of many raw materials and manufactur-
among the three test methods have been found to exist when
ing process variables which influence shear properties uni-
these test methods are applied to plywood of clear straight-
formly throughout the specimen. The test method is unsuited
grained veneers. Therefore, when comparisons are made
for determining effects of grade and manufacturing features
among test results, it is recommended that the same test
such as density variations, knots, and core gaps within the
method be used throughout.
specimen.
1.1.2 Test Method B: Large Panel Shear Test—This test
1.3 This standard does not purport to address all of the
method is regarded as giving the most accurate modulus of safety concerns, if any, associated with its use. It is the
rigidity and is therefore recommended for elastic tests of responsibility of the user of this standard to establish appro-
materials to be used in stress analysis studies of test structures.
priate safety and health practices and determine the applica-
This test method also yields excellent shear strength values for
bility of regulatory limitations prior to use.
clear material. However, in spite of the large size of the
specimen, failures generally occur only in narrow zones at the
2. Referenced Documents
perimeter of the test area. This characteristic, a result of the
2.1 ASTM Standards:
heavy perimeter framing, causes this test method to be gener-
D2395 Test Methods for Specific Gravity of Wood and
ally unsuited for determining grade and manufacturing effects
Wood-Based Materials
such as density variations, core gaps, and knots that are not
D4442 Test Methods for Direct Moisture Content Measure-
uniformly distributed throughout the panel. Generally, only in
ment of Wood and Wood-Base Materials
These test methods are under the jurisdiction of ASTM Committee D07 on
Wood and are 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 April 1, 2007. Published April 2007. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1969. Last previous edition approved in 2001 as D2719 – 89 (2001). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D2719-89R07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2719 − 89 (2007)
3. Significance and Use
3.1 The strength and modulus of rigidity of structural panels
in shear through-the-thickness obtained by these test methods
are required for the rigorous design of many lumber-panel
structural components such as trusses with panel gussets, box
beams,foldedplateroofs,andspaceplanestructures,aswellas
floor and roof diaphragms, and shear walls. These properties
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
Metric Equivalents
contain fine checks or separations parallel to the grain on the
1 1
in. ⁄16 ⁄2
knife side of the veneer that are produced as the knife is forced
mm 1.6 12.7
through the wood. These checks are termed “knife checks” to
FIG. 1 Small Panel Shear Specimen and Dimensions
distinguish them from occasional checks that may be formed
on the opposite side of the veneer by forces at the compression
bar, and from checks caused by drying.Average depth of knife
checks has been found to strongly influence shear properties in
thickness at two diagonally opposite corners and the dimen-
plywood panels and may be of significance in veneer incorpo-
sions of the shear area inside the reinforcing blocks shall be
rated in composite panels. Measurement of depth of knife
determined and recorded to the nearest 0.3 % or 0.001 in.
checks is recommended in these test methods.
(0.025 mm), whichever is larger.
3.3 To control or define other variables influencing shear
5.3 Loading—Applytheloadbyspecialsteelloadingblocks
properties, these test methods require determination of mois-
which articulate with the rollers and pins attached to the test
ture content and elapsed time to failure. The conditioning of
specimen. The angle between faces of the loading block shall
test material in controlled atmosphere and determination of
be 90° and between each face and the base the angle shall be
specific gravity are recommended.
45°. A spherical bearing block, preferably of the suspended,
self-aligning type, shall be employed in the loading system.
4. Control of Moisture Content
Apply the load continuously throughout the test with a uniform
4.1 Structural panel samples to be tested at a specific
motion of the movable head of the testing machine equal to
temperature/relative humidity shall be conditioned to approxi-
0.0025 in./in. of test area diagonal length/min (0.0025 mm/
mate constant weight in controlled atmospheric conditions
mm/min) corresponding to a shear strain rate of 0.005 in./in./
beforegluingwoodrails.Conditioningoffabricatedspecimens
min (0.005 mm/mm/min) within a permissible variation of
at the same temperature and relative humidity shall be contin-
625 %.
ued until the adhesive has cured sufficiently to ensure adequate
5.3.1 Load each of the eight reinforcing blocks through
bond strength. For approximating moisture conditions of struc-
roller brackets clamped to the reinforcing block across its
tural panels used under dry conditions, a relative humidity of
width or attached by other means and applying a compressive
65 6 2 % at a temperature of 68 6 6°F (20 6 3°C) is
force to the end of the reinforcing block through a surface
recommended.
2 2
contact area of at least 0.75 in. (484 mm ). These bearing
surfaces shall be firmly seated against the ends of their
5. Test Method A—Small Panel Shear Test
respective reinforcing blocks during assembly. Rollers shall be
5.1 Summary—A specimen having a square shear area
centered at the inner edge of the reinforcing block and 1.25 in.
bounded on each side by solid wood blocks glued to both sides
(31.8 mm) from the loaded end of the reinforcing block.
ofthespecimenisloadedincompressionalongonediagonalin
Moderate clamping pressure holding brackets to the reinforc-
a conventional testing machine. Forces are applied to the
ing blocks applied perpendicular to the plane of the panel is
glued-on blocks through a roller bracket assembly which
permitted but shall not be excessive.
causes the resultant forces to act collinearly with the edge of
5.3.1.1 Fig. 2 illustrates detail of suitable roller brackets and
the shear test area. This loading method most nearly produces
their method of attachment to the reinforcing blocks with small
uniform pure shear. Shear strength is determined from maxi-
wood wedges. Fig. 3 shows a specimen loaded by means of
mum load, and modulus of rigidity may be calculated from
roller brackets, and Fig. 4 gives working drawings for these
measurements of compression strain along the compression
brackets. Brackets are clamped across the width of the rein-
diagonal of the specimen.
forcing blocks by driving small wedges between a projection
5.2 Test Specimen—Dimensions shown in Fig. 1 of the on the bracket and the reinforcing block. The clamping bolt is
panel specimen and reinforcing blocks depend upon panel used to apply moderate clamping pressure perpendicular to the
thickness. Distance between blocks, L, shall not exceed 20 planeofthespecimen.Otherbracketdevicesconformingtothe
times specimen thickness, and block width and thickness shall requirements of 5.3.1 are permitted but shall be described in
not be less than 5 and 2.5 times specimen thickness, respec- detail in the report of test results.
tively. Reinforcing blocks shall be of birch, maple, or other 5.3.1.2 Measure the elapsed time from initiation of loading
wood of similar strength and rigidity. The average of specimen to the maximum load and record to the nearest ⁄2 min.
D2719 − 89 (2007)
FIG. 2 Small Panel Shear Specimen with Roller Brackets
5.4 Measurement of Deformation—When deformation data G 5 0.3536 P/∆ [L / L·t ] (2)
~ ! ~ !
are desired for calculation of elastic properties, strain-
where:
measuring devices having minimum gage length of 1 in. (25
G = modulus of rigidity, psi (N/m ),
mm) shall be attached to both sides of the specimen and shall
P/∆ = slope of force/deformation curve, lbf/in. (N/m),
measure compression strain of the vertical (or compression)
L = gage length, in. (m), and
diagonal, the gages being centered at its midpoint on each side.
t = thickness of shear specimen, in. (m).
A larger gage length is preferred but shall not exceed one half
the length of the diagonal. Instruments and the accuracy of
6. Test Method B—Large Panel Shear Test
their recording shall be to the nearest 0.0001 in. (0.0025 mm)
or 2 % of expected ultimate strain, whichever is smaller. Strain 6.1 Summary—A specimen having a square shear area is
readings of the two gages shall be averaged for computation of loaded through heavy lumber rails glued to both sides of the
elastic properties. specimen at all four edges of the shear area. Loading by a
system of pins and yokes applies forces to the rails having a
5.5 Calculation:
resultant acting at the inside edge of the shear area. Maximum
5.5.1 Calculate the maximum shear stress or shear stress at
shear strength is determined from maximum load and modulus
the proportional limit as follows:
of rigidity from elongation of the tension diagonal and corre-
T 5 0.707 P/Lt (1)
~ !
sponding loads.
where:
6.2 Test Specimens—Fig. 5 gives detail of the specimen as
T = shear stress, psi (N/m ),
well as a suitable loading method. Shear area of the specimen
P = load (force), lbf (N),
shall not be less than 24 in. (610 mm) on a side, and shall not
L = length of side of shear area, in. (m), (Fig. 1), and
exceed 48 times total specimen thickness. When structural
t = thickness of shear specimen, in. (m).
1 1
panels less than ⁄2 in. (12.7 mm) thick or less than ⁄48 the side
5.5.2 Calculate modulus of rigidity from deformation data of the shear area is to be tested for shear strength, two or more
as follows: thicknesses of structural panels may be glued together (major
D2719 − 89 (2007)
FIG. 3 Small Panel Shear Specimen with Loading and Strain-Measuring Apparatus Placed in Testing Machine
axis parallel) to form a test panel of the required thickness. area. If the ends of rails are compression loaded, the jigs shall
Specimens to be tested for modulus of rigidity only may be of restrain any tendency for the rails to deflect laterally from the
lesser thickness provided sufficient data can be obtained before plane of the specimen. Fig. 6 shows the loading forces, their
the test is halted due to initiation of buckling. Lumber rails
resultants, and their components. Any lateral forces applied to
havingalengthequaltothesideofthesheararea,thicknessnot
the rails parallel to the plane of the specimen or any lateral
1 1
less than ⁄25 and width not less than ⁄6 the length of one side
component parallel to the plane of the specimen of a force
of the shear area shall be glued to the structural panels with a
applied to the rails shall not exceed ⁄8 of the axial force
rigid adhesive. Wider rails may be necessary to prevent rolling
component.
shear failures between thick or high-strength panels and the
6.3.1 Suitable loading equipment is illustrated in Fig. 5 and
rails. Corners of the structural panels specimen shall be
Fig. 7. Major compression forces are applied by yokes to the
notched with the inside corner of the notch provided with a
endsoftherailsataslightangletotherailaxisthroughbearing
fillet of ⁄2-in. (12.7-mm) radius as shown in Fig. 5. Ends of the
plates.At its other end, a pin having a notched end centers the
rails to which loads are applied shall form a flat plane
pin and yoke over the inside edge of the rail. Forces acting at,
perpendicular to the plane of the specimen. Use of a jig to
and parallel to, the inner edge of the rail are applied to these
position rails accurately at the time of assembly or a light saw
pins by short links. At its other end, the link connects to a pi
...
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