ASTM D198-22a

Standard Test Methods of Static Tests of Lumber in Structural Sizes

SIGNIFICANCE AND USE
6.1 The flexural properties established by this test method provide:  
6.1.1 Data for use in development of grading rules and specifications;  
6.1.2 Data for use in development of design values for structural members;  
6.1.3 Data on the influence of imperfections on mechanical properties of structural members;  
6.1.4 Data on strength properties of different species or grades in various structural sizes;  
6.1.5 Data for use in checking existing equations or hypotheses relating to the structural behavior;  
6.1.6 Data on the effects of chemical or environmental conditions on mechanical properties;  
6.1.7 Data on effects of fabrication variables such as depth, taper, notches, or type of end joint in laminations; and  
6.1.8 Data on relationships between mechanical and physical properties.  
6.2 Procedures are described here in sufficient detail to permit duplication in different laboratories so that comparisons of results from different sources will be valid. Where special circumstances require deviation from some details of these procedures, these deviations shall be carefully described in the report (see Section 11).
SCOPE
1.1 These test methods cover the evaluation of lumber and wood-based products in structural sizes by various testing procedures.  
1.2 The test methods appear in the following order:    
Sections    
Flexure  
4 – 11  
Compression (Short Specimen)  
13 – 20  
Compression (Long Specimen)  
21 – 28  
Tension  
29 – 36  
Torsion  
37 – 44  
Shear Modulus  
45 – 52  
1.3 Notations and symbols relating to the various testing procedures are given in Appendix X1.  
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 79.040 - Wood, sawlogs and sawn timber
• Technical Committee: D07 - Wood
• Drafting Committee: D07.01 - Fundamental Test Methods and Properties

Relations

• Refers: ASTM D3737-18(2023)e1 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Oct-2023
• Refers: ASTM D4442-20 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
• Effective Date: 01-Mar-2020
• Refers: ASTM D4761-19 - Standard Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
• Effective Date: 01-Apr-2019
• Refers: ASTM D4761-18 - Standard Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
• Effective Date: 01-Nov-2018
• Refers: ASTM D3737-18e1 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Apr-2018
• Refers: ASTM D3737-18 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Apr-2018
• Refers: ASTM D4442-16 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
• Effective Date: 15-Nov-2016
• Refers: ASTM D4442-15 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
• Effective Date: 01-Jun-2015
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014
• Refers: ASTM D2395-14 - Standard Test Methods for Density and Specific Gravity (Relative Density) of Wood and Wood-Based Materials
• Effective Date: 01-May-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM D2395-14e1 - Standard Test Methods for Density and Specific Gravity (Relative Density) of Wood and Wood-Based Materials
• Effective Date: 01-May-2014
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM D4761-13 - Standard Test Methods for Mechanical Properties of Lumber and Wood-Base Structural Material
• Effective Date: 01-Apr-2013

Overview

ASTM D198-22a - Standard Test Methods of Static Tests of Lumber in Structural Sizes specifies comprehensive laboratory procedures for assessing the mechanical properties of lumber and wood-based structural members. Developed by ASTM International, this standard provides essential methods for evaluating structural wood products, including sawn lumber, glued laminated timber (glulam), structural composite lumber, and prefabricated wood I-joists. These test methods are critical for establishing grading rules, specifying design values, and ensuring the safety and performance of wood structures.

This standard is recognized for its applicability to a wide variety of wood-based construction products. It details processes for measuring several key mechanical properties-such as flexural, compressive, tensile, and torsional strength-by employing static tests on specimens of structural dimensions. The results enable a direct comparison between products from different sources, supporting quality assurance and product uniformity.

Key Topics

• Mechanical Properties Analysis: Measures flexural strength (bend tests), compression (parallel to grain), tension, torsion, and shear modulus in lumber and wood-based products of structural sizes.
• Specimen Preparation and Description: Provides guidelines for documenting source, species, treatment, and observable defects or modifications that may affect test results.
• Test Procedures: Step-by-step guidance for setting up apparatus, loading configurations, deflection measurement, testing rates, and load application.
• Data Utility:
  • Provides data for development of grading rules
  • Informs design values for structural applications
  • Analyzes the influence of imperfections and environmental factors
  • Assists in checking structural behavior models and equations
  • Evaluates the impact of fabrication variables (e.g., notches, end joints)
  • Correlates mechanical with physical properties like density and moisture content
• Reporting and Repeatability: Outlines the information required for consistent reporting, enabling valid comparison of results across different laboratories or studies.

Applications

ASTM D198-22a is vital in a range of practical scenarios for the wood products sector, especially for timber engineering and construction industries:

• Product Certification and Quality Control: Assures that lumber or engineered wood products used in frameworks, bridges, floors, and similar structures meet specified performance benchmarks.
• Structural Design and Engineering: Supplies engineers and architects with reliable data to assign appropriate design values and safety factors for structural elements.
• Grading and Specification Development: Supports regulatory bodies, manufacturers, and specifiers in creating or updating grading rules and product catalogs for structural lumber.
• Material Research and Development: Facilitates product innovation (e.g., development of high-strength glulams or composite timbers) and supports academic or industrial research on new wood-based structural products.
• Regulatory Compliance: Essential for demonstrating compliance with building codes or technical standards that require proof of mechanical performance for specific wood products.

Related Standards

ASTM D198-22a references and works alongside several other ASTM standards and documents within the field of wood testing and terminology, including:

• ASTM D9 - Terminology Relating to Wood and Wood-Based Products
• ASTM D2395 - Test Methods for Density and Specific Gravity of Wood and Wood-Based Materials
• ASTM D2915 - Practice for Sampling and Data Analysis for Structural Wood
• ASTM D3737 - Practice for Establishing Allowable Properties for Structural Glued Laminated Timber
• ASTM D4442 - Methods for Moisture Content Measurement of Wood
• ASTM D4761 - Test Methods for Mechanical Properties of Wood-Based Structural Materials

Leveraging ASTM D198-22a ensures reproducible, reliable assessment of the mechanical properties of timber and structural materials, supporting a uniform, science-based approach in construction and material selection. This foundation improves confidence in wood’s performance as a core material in modern structures.

Standards Content (Sample)

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.
Designation: D198 − 22a
Standard Test Methods of
Static Tests of Lumber in Structural Sizes
This standard is issued under the fixed designation D198; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Numerous evaluations of structural members of sawn lumber have been conducted in accordance
withTest Methods D198.While the importance of continued use of a satisfactory standard should not
beunderestimated,theoriginalstandard(1927)wasdesignedprimarilyforsawnlumbermaterial,such
asbridgestringersandjoists.Withtheadventofstructuralgluedlaminated(glulam)timbers,structural
composite lumber, prefabricated wood I-joists, and even reinforced and prestressed timbers, a
procedure adaptable to a wider variety of wood structural members was required and Test Methods
D198 has been continuously updated to reflect modern usage.
The present standard provides a means to evaluate the flexure, compression, tension, and torsion
strengthandstiffnessoflumberandwood-basedproductsinstructuralsizes.Aflexuraltesttoevaluate
the shear stiffness is also provided. In general, the goal of the D198 test methods is to provide a
reliable and repeatable means to conduct laboratory tests to evaluate the mechanical performance of
wood-basedproducts.Whilemanyofthepropertiestestedusingthesemethodsmayalsobeevaluated
using the field procedures of Test Methods D4761, the more detailed D198 test methods are intended
to establish practices that permit correlation of results from different sources through the use of more
uniform procedures.The D198 test methods are intended for use in scientific studies, development of
designvalues,qualityassurance,orotherinvestigationswhereamoreaccuratetestmethodisdesired.
Provision is made for varying the procedure to account for special problems.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 These test methods cover the evaluation of lumber and
responsibility of the user of this standard to establish appro-
wood-based products in structural sizes by various testing
priate safety, health, and environmental practices and deter-
procedures.
mine the applicability of regulatory limitations prior to use.
1.2 The test methods appear in the following order:
1.6 This international standard was developed in accor-
Sections
dance with internationally recognized principles on standard-
Flexure 4–11
ization established in the Decision on Principles for the
Compression (Short Specimen) 13–20
Development of International Standards, Guides and Recom-
Compression (Long Specimen) 21–28
Tension 29–36
mendations issued by the World Trade Organization Technical
Torsion 37–44
Barriers to Trade (TBT) Committee.
Shear Modulus 45–52
1.3 Notations and symbols relating to the various testing
2. Referenced Documents
procedures are given in Appendix X1. 2
2.1 ASTM Standards:
1.4 Thevaluesstatedininch-poundunitsaretoberegarded
D9Terminology Relating to Wood and Wood-Based Prod-
as standard. The values given in parentheses are mathematical ucts
conversions to SI units that are provided for information only
D1165Nomenclature of Commercial Hardwoods and Soft-
and are not considered standard. woods
D2395TestMethodsforDensityandSpecificGravity(Rela-
tive Density) of Wood and Wood-Based Materials
These test methods are under the jurisdiction of ASTM Committee D07 on
Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental
Test Methods and Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2022. Published October 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1924. Last previous edition approved in 2022 as D198 – 22. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D0198-22a. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D198 − 22a
D2915Practice for Sampling and Data-Analysis for Struc- 3.2.5 span (ℓ)—the total distance between reactions on
tural Wood and Wood-Based Products which a flexure specimen or shear modulus specimen is
D3737Practice for Establishing Allowable Properties for supported to accommodate a transverse load (Fig. 1).
Structural Glued Laminated Timber (Glulam)
3.2.6 span-depth ratio (ℓ/d)—the numerical ratio of total
D4442Test Methods for Direct Moisture Content Measure-
span divided by depth of a flexure specimen or shear modulus
ment of Wood and Wood-Based Materials
specimen.
D4761Test Methods for Mechanical Properties of Lumber
3.2.7 structural member—sawn lumber, glulam, structural
and Wood-Based Structural Materials
composite lumber, prefabricated wood I-joists, or other similar
D7438Practice for Field Calibration and Application of
product for which strength or stiffness, or both, are primary
Hand-Held Moisture Meters
criteriafortheintendedapplicationandwhichusuallyareused
E4Practices for Force Calibration and Verification of Test-
in full length and in cross-sectional sizes greater than nominal
ing Machines
2in. by 2in. (38mm by 38mm).
E6Terminology Relating to Methods of MechanicalTesting
E83Practice for Verification and Classification of Exten-
FLEXURE
someter Systems
E177Practice for Use of the Terms Precision and Bias in
4. Scope
ASTM Test Methods
4.1 Thistestmethodcoversthedeterminationoftheflexural
E691Practice for Conducting an Interlaboratory Study to
properties of structural members. This test method is intended
Determine the Precision of a Test Method
primarily for members with rectangular cross sections but is
E2309Practices forVerification of Displacement Measuring
also applicable to members with round and irregular shapes,
Systems and Devices Used in Material Testing Machines
such as round posts, pre-fabricated wood I-joists, or other
special sections.
3. Terminology
3.1 Definitions—SeeTerminologyE6,TerminologyD9,and
5. Summary of Test Method
Nomenclature D1165.
5.1 The flexure specimen is subjected to a bending moment
3.2 Definitions:Definitions of Terms Specific to This Stan-
bysupportingitnearitsends,atlocationscalledreactions,and
dard:
applying transverse loads symmetrically imposed between
3.2.1 composite wood member—a laminar construction
these reactions. The specimen is deflected at a prescribed rate
comprising a combination of wood and other simple or
until failure occurs. Coordinated observations of loads and
complexmaterialsassembledandintimatelyfixedinrelationto
deflections are made.
each other so as to use the properties of each to attain specific
structural advantage for the whole assembly.
6. Significance and Use
3.2.2 depth (d)—the dimension of the flexure specimen or
6.1 The flexural properties established by this test method
shear modulus specimen that is perpendicular to the span and
provide:
parallel to the direction in which the load is applied (Fig. 1).
6.1.1 Data for use in development of grading rules and
3.2.3 shear span—twotimesthedistancebetweenareaction
specifications;
and the nearest load point for a symmetrically loaded flexure
6.1.2 Data for use in development of design values for
specimen (Fig. 1).
structural members;
3.2.4 shear span-depth ratio—the numerical ratio of shear 6.1.3 Data on the influence of imperfections on mechanical
span divided by depth of a flexure specimen. properties of structural members;
FIG. 1 Flexure Test Method—Example of Two-Point Loading
D198 − 22a
6.1.4 Data on strength properties of different species or
grades in various structural sizes;
6.1.5 Dataforuseincheckingexistingequationsorhypoth-
eses relating to the structural behavior;
6.1.6 Data on the effects of chemical or environmental
conditions on mechanical properties;
6.1.7 Data on effects of fabrication variables such as depth,
taper, notches, or type of end joint in laminations; and
6.1.8 Data on relationships between mechanical and physi-
cal properties.
6.2 Procedures are described here in sufficient detail to
permitduplicationindifferentlaboratoriessothatcomparisons
of results from different sources will be valid. Where special
circumstances require deviation from some details of these
procedures, these deviations shall be carefully described in the
report (see Section 11).
7. Apparatus
7.1 Testing Machine—A device that provides (1) a rigid
frametosupportthespecimenyetpermititsdeflectionwithout
restraint, (2) a loading head through which the force is applied
without high-stress concentrations in the specimen, and (3)a
FIG. 2 Example of Bearing Plate (A), Rollers (B), and Reaction-
force-measuring device that is calibrated to ensure accuracy in
Alignment-Rocker (C), for Small Flexure Specimens
accordance with Practices E4.
7.2 Support Apparatus—Devicesthatprovidesupportofthe sions shall be made to prevent eccentric loading of the load
measuring device (see Appendix X5).
specimen at the specified span.
7.3.1 Load Bearing Blocks—The load shall be applied
7.2.1 Reaction Bearing Plates—The specimen shall be sup-
through bearing blocks (Fig. 1), which are of sufficient thick-
ported by metal bearing plates to prevent damage to the
ness and extending entirely across the specimen width to
specimenatthepointofcontactwiththereactionsupport(Fig.
eliminate high-stress concentrations at places of contact be-
1).Theplatesshallbeofsufficientlength,thickness,andwidth
tween the specimen and bearing blocks. Load shall be applied
to provide a firm bearing surface and ensure a uniform bearing
to the blocks in such a manner that the blocks shall be
stress across the width of the specimen.
permittedtorotateaboutanaxisperpendiculartothespan(Fig.
7.2.2 Reaction Supports—The bearing plates shall be sup-
4). To prevent specimen deflection without restraint in case of
ported by devices that provide unrestricted longitudinal defor-
two-point loading, metal bearing plates and rollers shall be
mation and rotation of the specimen at the reactions due to
used in conjunction with one or both load-bearing blocks,
loading. Provisions shall be made to restrict horizontal trans-
depending on the reaction support conditions (see Appendix
lation of the specimen (see 7.3.1 and Appendix X5).
X5). Provisions such as rotatable bearings or shims shall be
7.2.3 Reaction Bearing Alignment—Provisions shall be
made to ensure full contact between the specimen and the
made at the reaction supports to allow for initial twist in the
loading blocks. The size and shape of these loading blocks,
length of the specimen. If the bearing surfaces of the specimen
plates, and rollers may vary with the size and shape of the
at its reactions are not parallel, then the specimen shall be
specimen, as well as for the reaction bearing plates and
shimmedortheindividualbearingplatesshallberotatedabout
supports. For rectangular structural products, the loading
an axis parallel to the span to provide full bearing across the
surface of the blocks shall have a radius of curvature equal to
widthofthespecimen.Supportswithlateralself-alignmentare
two to four times the specimen depth. Specimens having
normally used (Fig. 2).
circular or irregular cross-sections shall have bearing blocks
7.2.4 Lateral Support—Specimens that have a depth-to-
that distribute the load uniformly to the bearing surface and
width ratio (d/b) of three or greater are subject to out-of-plane
permit unrestrained deflections.
lateral instability during loading and require lateral support.
7.3.2 Load Points—Location of load points relative to the
Lateral support shall be provided at points located about
reactions depends on the purpose of testing and shall be
halfway between a reaction and a load point. Additional
recorded (see Appendix X5).
supports shall be permitted as required to prevent lateral-
7.3.2.1 Two-Point Loading—The total load on the specimen
torsionalbuckling.Eachsupportshallallowverticalmovement
shall be applied equally at two points equidistant from the
without frictional restraint but shall restrict lateral displace-
reactions. The two load points will normally be at a distance
ment (Fig. 3).
from their reaction equal to one third of the span (ℓ/3)
7.3 Load Apparatus—Devices that transfer load from the (third-point loading), but other distances shall be permitted for
testing machine at designated points on the specimen. Provi- special purposes.
D198 − 22a
FIG. 3 Example of Lateral Support for Long, Deep Flexure Specimens
positioned such that a line perpendicular to the neutral axis at
thelocationofthereferencepoint,passesthroughthesupport’s
center of rotation.
7.4.1.2 The true or shear-free modulus of elasticity (E )
sf
shall be calculated using the shear-free deflection. The refer-
encepointsfortheshear-freedeflectionmeasurementsshallbe
positioned at cross-sections free of shear and stress concentra-
tions (see Appendix X5).
NOTE1—Theapparentmodulusofelasticity(E )maybeconvertedto
app
the shear-free modulus of elasticity (E ) by calculation, assuming that the
sf
shear modulus (G) is known. See Appendix X2.
7.4.2 Wire Deflectometer—A wire stretched taut between
twonails,smoothdowels,orotherroundedfixturesattachedto
the neutral axis of the specimen directly above the reactions
and extending across a scale attached at the neutral axis of the
specimen at mid-span shall be permitted to read deflections
withatelescopeorreadingglasstomagnifytheareawherethe
wire crosses the scale. When a reading glass is used, a
reflectivesurfaceplacedadjacenttothescalewillhelptoavoid
parallax.
FIG. 4 Example of Curved Loading Block (A), Load-Alignment 7.4.3 Yoke Deflectometer—Asatisfactory device commonly
Rocker (B), Roller-Curved Loading Block (C), Load Evener (D),
used to measure deflection of the center of the specimen with
and Deflection-Measuring Apparatus (E)
respect to any point along the neutral axis consists of a
lightweight U-shaped yoke suspended between nails, smooth
dowels, or other rounded fixtures attached to the specimen at
its neutral axis. An electronic displacement gauge, dial
7.3.2.2 Center-Point Loading—A single load shall be ap-
micrometer, or other suitable measurement device attached to
plied at mid-span.
the center of the yoke shall be used to measure vertical
7.3.2.3 Forevaluationofshearproperties,center-pointload-
displacement at mid-span relative to the specimen’s neutral
ing or two-point loading shall be used (see Appendix X5).
axis (Fig. 4).
7.4 Deflection-Measuring Apparatus:
7.4.4 Alternative Deflectometers—Deflectometers that do
7.4.1 General—For modulus of elasticity calculations, de-
not conform to the general requirements of 7.4.1 shall be
vices shall be provided by which the deflection of the neutral
permitted provided the mean deflection measurements are not
axis of the specimen at the center of the span is measured with
significantly different from those devices conforming to 7.4.1.
respect to a straight line joining two reference points equidis-
The equivalency of such devices to deflectometers, such as
tantfromthereactionsandontheneutralaxisofthespecimen.
those described in 7.4.2 or 7.4.3, shall be documented and
7.4.1.1 The apparent modulus of elasticity (E ) shall be
app
demonstrated by comparison testing.
calculated using the full-span deflection (∆). The reference
points for the full-span deflection measurements shall be NOTE 2—Where possible, equivalency testing should be undertaken in
D198 − 22a
the same type of product and stiffness range for which the device will be
and intended use, so that no modification of these dimensions
used. Issues that should be considered in the equivalency testing include
is involved. The length, however, will be established by the
theeffectofcrushingatandinthevicinityoftheloadandreactionpoints,
type of data desired (see Appendix X5). The span length is
twist in the specimen, and natural variation in properties within a
determined from knowledge of specimen depth, the distance
specimen.
between load points, as well as the type and orientation of
7.4.5 Accuracy—The deflection measurement devices and
material in the specimen. The total specimen length includes
recording system shall be capable of at least a Class B rating
the span (measured from center to center of the reaction
when evaluated in accordance with Practice E2309.
supports) and the length of the overhangs (measured from the
center of the reaction supports to the ends of the specimen).
8. Flexure Specimen
Sufficient length shall be provided so that the specimen can
8.1 Material—Theflexurespecimenshallconsistofastruc-
accommodatethebearingplatesandrollersandwillnotslipoff
tural member.
the reactions during test.
8.2 Identification—Material or materials of the specimen
8.5.1 For the evaluation of flexural strength, the overhang
shallbeidentifiedasfullyaspossiblebyincludingtheoriginor
beyond the span shall be minimized, as the measured flexural
source of supply, species, and history of drying and
capacity is influenced by the length of the overhang. The
conditioning, chemical treatment, fabrication, and other perti-
reaction bearing plates shall be at least long enough to prevent
nent physical or mechanical details that potentially affect the
bearing failures. The specimen overhang beyond the test span
strengthorstiffness.Detailsofthisinformationshalldependon
shall not extend by more than four times the member depth. If
the material or materials in the structural member. For
longer overhangs are necessary to satisfy the test objectives,
example, wood beams or joists would be identified by the
the length of overhang shall be reported, and the calculated
character of the wood, that is, species, source, and so forth,
bending strength shall be reduced to account for the weight of
whereasstructuralcompositelumberwouldbeidentifiedbythe
the overhangs. The original bending strength, the overhang-
grade, species, and source of the material (that is, product
adjusted bending strength, and the method of adjustment shall
manufacturer, manufacturing facility, etc.).
be reported.
8.5.2 For evaluation of shear properties, the overhang be-
8.3 Specimen Measurements—The weight and dimensions
yond the span shall be minimized, as the shear capacity is
(length and cross-section) of the specimen shall be measured
before the test to three significant figures. Sufficient measure- influenced by the length of the overhang. The reaction bearing
plates shall be the minimum length necessary to prevent
ments of the cross section shall be made along the length to
describe the width and depth of rectangular specimens and to bearingfailures.Thespecimenshallnotextendbeyondtheend
ofthereactionplates(Fig.X5.3inAppendixX5)unlesslonger
determine the critical section or sections of non-uniform (or
non-prismatic) specimens. The physical characteristics of the overhangs are required to simulate a specific design condition.
specimenasdescribedbyitsdensityorspecificgravityshallbe
permitted to be determined in accordance with Test Methods 9. Procedure
D2395.
9.1 Conditioning—Unless otherwise indicated in the re-
8.4 Specimen Description—The inherent strength-reducing
search program or material specification, condition the speci-
characteristics or intentional modifications of the composition men to constant weight so it is in moisture equilibrium under
of the specimen shall be fully described by recording the size
the desired environmental conditions. Approximate moisture
andlocationofsuchfactorsincluding,butnotlimitedto,knots, contents with moisture meters or measure more accurately by
checks, and reinforcements. Size and location of intentional
weights of samples in accordance with Test Methods D4442.
modifications such as placement of laminations, glued joints,
9.2 Test Setup—Determine the size of the specimen, the
and reinforcements shall be recorded during the fabrication
span, and the shear span in accordance with 7.3.2 and 8.5.
process or prior to testing. Where required by the test objec-
Locatetheflexurespecimensymmetricallyonitssupportswith
tives for materials with discrete strength-reducing characteris-
load bearing and reaction bearing blocks as described in 7.2 –
tics or intentional modifications, sketch or photographic re-
7.4. The specimen shall be adequately supported laterally in
cords shall be made of each face and the ends. These sketches
accordance with 7.2.4. Set apparatus for measuring deflections
or photographs shall show the size, location, and type of
in place (see 7.4). Full contact shall be attained between
strength-reducing characteristics or intentional modifications,
support bearings, loading blocks, and the specimen surface.
including: reinforcements, glued joints, slope of grain, knots,
9.3 Speed of Testing—The loading shall progress at a
distribution of sapwood and heartwood, location of pitch
constant deformation rate such that the average time to
pockets, direction of annual rings, and such abstract factors as
maximum load for the test series shall be at least 4 min. It is
crook,bow,cup,twist,whichmightaffecttheflexuralstrength.
permissible to initially test a few random specimens from a
Where required by the test objectives, the surface features of
series at an alternate rate as the test rate is refined. Otherwise,
each specimen shall be described in sufficient detail to deduce
the selected rate shall be held constant for the test series.
the extent of the strength-reducing characteristics within the
cross section.
9.4 Load-Deflection Curves:
8.5 Rules for Determination of Specimen Length—The 9.4.1 Obtain load-deflection data with apparatus described
cross-sectional dimensions of structural products usually have in 7.4.1. When the objective of the deflection measurement is
established sizes, depending upon the manufacturing process only to determine the specimen stiffness or modulus of
D198 − 22a
elasticity, it shall be permitted to remove the deflection- 11.1.8 Computed physical and mechanical properties, in-
measuring apparatus at any point after either the proportional cludingspecificgravityordensity(asapplicable)andmoisture
limit or 40 % of the expected average maximum load is content, flexural strength, stress at proportional limit, modulus
achieved. Note the load at first failure, at the maximum load, of elasticity, calculation methods (Note 3), and a statistical
and at points of sudden change in specimen behavior. If the measure of variability of these values,
deflection measurement is continued to failure, then it shall
NOTE 3—Appendix X2 provides acceptable formulae and guidance for
also be recorded at the same points. Continue loading until
determining the flexural properties.
completefailureoranarbitraryterminalloadhasbeenreached.
11.1.9 Description of failure, and
9.4.2 If an additional deflection-measuring apparatus is
11.1.10 Details of any deviations from the prescribed or
provided to measure the shear-free deflection (∆ ) over a
sf
recommended methods as outlined in the standard.
second distance (ℓ ) in accordance with 7.4.1.2, such load-
sf
deflection data shall be obtained until either the proportional
12. Precision and Bias
limit or 40 % of the expected average maximum load are
12.1 Interlaboratory Test Program—An interlaboratory
achieved.
study (ILS) was conducted in 2006–2007 by sixteen laborato-
9.5 Record of Failures—Describe failures in detail as to
ries in the United States and Canada in accordance with
type, manner, and order of occurrence, and position in the 3
Practice E691. The scope of this study was limited to the
specimen. Record descriptions of the failures and relate them
determination of the apparent modulus of elasticity of three
to specimen drawings or photographs referred to in 8.4. Also
different 2×4 nominal sized products tested both edgewise
record notations as the order of their occurrence on such
and flatwise. The deflection of each flexure specimen’s neutral
references. Hold the section of the specimen containing the
axis at the mid-span was measured with a yoke according to
failure for examination and reference until analysis of the data
7.4. Five specimens of each product were tested in a round-
has been completed.
robin fashion in each laboratory, with four test results obtained
9.6 Moisture Content Determination—Following the test, for each specimen and test orientation. The resulting precision
measure the moisture content of the specimen at a location indexes are shown in Table 1. For further discussion, see
away from the end and as close to the failure zone as practical Appendix X5.4.
in accordance with the procedures outlined in Test Methods
12.2 The terms of repeatability and reproducibility are used
D4442. Alternatively, the moisture content for a wood speci-
as specified in Practice E177.
men shall be permitted to be determined using a calibrated
12.3 Bias—The bias is not determined because the apparent
moisture meter according to Standard Practice D7438. The
modulus of elasticity is defined in terms of this method, which
number of moisture content samples shall be determined using
is generally accepted as a reference (Note 4).
Practice D7438 guidelines, with consideration of the expected
moisture content variability, and any related requirements in
NOTE 4—Use of this method does not necessarily eliminate laboratory
bias or ensure a level of consistency necessary for establishing reference
the referenced product standards.
values.The users are encouraged to participate in relevant interlaboratory
studies (that is, an ILS involving sizes and types of product similar to
10. Calculation
those regularly tested by the laboratory) to provide evidence that their
10.1 Compute physical and mechanical properties and their
implementation of the Test Method provides levels of repeatability and
appropriate adjustments for the specimen in accordance with reproducibility at least comparable to those shown in Table 1. See also
X5.4.2 and X5.4.3.
the relationships in Appendix X2.
COMPRESSION PARALLEL TO GRAIN (SHORT
11. Report
SPECIMEN, NO LATERAL SUPPORT, ℓ/r < 17)
11.1 Report the following information:
11.1.1 Complete identification of the specimen, including
13. Scope
species,origin,shapeandform,fabricationprocedure,typeand
13.1 This test method covers the determination of the
location of imperfections or reinforcements, and pertinent
compressive properties of specimens taken from structural
physical or chemical characteristics relating to the quality of
memberswhensuchaspecimenhasaslendernessratio(length
the material,
to least radius of gyration) of less than 17. The method is
11.1.2 History of seasoning and conditioning,
intended primarily for structural members with rectangular
11.1.3 Loading conditions to portray the load and support
cross sections, but is also applicable to irregularly shaped
mechanics, including type of equipment, lateral supports, if
studs, braces, chords, round poles, or special sections.
used, the location of load points relative to the reactions, the
size of load bearing blocks, reaction bearing plates, clear
14. Summary of Test Method
distances between load block and reaction plate and between
14.1 Thespecimenissubjectedtoaforceuniformlydistrib-
load blocks, and the size of overhangs, if present,
uted on the contact surface in a direction generally parallel to
11.1.4 Deflection apparatus,
11.1.5 Depth and width of the specimen or pertinent cross-
sectional dimensions,
Supporting data have been filed atASTM International Headquarters and may
11.1.6 Span length and shear span distance,
be obtained by requesting Research Report RR: RR:D07-1005. Contact ASTM
11.1.7 Rate of load application, Customer Service at [e-mail].
D198 − 22a
A
TABLE 1 Test Materials, Configurations, and Precision Indexes
Average
Repeatability Reproducibility
Apparent
Width × Depth Span Test Repeatability Reproducibility
Limits Limits
Modulus of
Product Test Orientation b×d ! Coefficient of Variation Coefficient of Variation
Elasticity
in. (mm) in. (mm) CV CV
r R
E
app
2CV d2CV 2CV d2CV
r r R R
psi × 10 (GPa)
Edgewise 1.5 × 3.5 63.0 2.17 1.4 % 2.0 % 2.7 % 3.8 % 4.0 % 5.6 %
(38 × 89) (1600) (14.9)
A
Flatwise 3.5 × 1.5 31.5 2.18 1.4 % 3.3 % 2.7 % 3.9 % 6.5 % 9.2 %
(89 × 38) (800) (15.0)
Edgewise 1.5 × 3.5 63.0 1.49 1.0 % 2.1 % 2.0 % 2.8 % 4.2 % 5.9 %
(38 × 89) (1600) (10.3)
B
Flatwise 3.5 × 1.5 31.5 1.54 1.3 % 2.7 % 2.6 % 3.6 % 5.3 % 7.5 %
(89 × 38) (800) (10.6)
Edgewise 1.5 × 3.5 63.0 2.35 1.3 % 2.0 % 2.5 % 3.5 % 3.9 % 5.5 %
(38 × 89) (1600) (16.2)
C
Flatwise 3.5 × 1.5 31.5 2.78 1.5 % 4.3 % 2.9 % 4.2 % 8.3 % 11.8 %
(89 × 38) (800) (19.2)
Edgewise 1.5 × 3.5 63.0 . . . 1.2 % 2.1 % 2.4 % 3.4 % 4.0 % 5.7 %
(38 × 89) (1600)
All Data
Flatwise 3.5 × 1.5 31.5 . . . 1.4 % 3.4 % 2.7 % 3.9 % 6.7 % 9.5 %
(89 × 38) (800)
A
The precision indexes are the average values of five specimens tested in eleven laboratories which were found to be in statistical control and in compliance with the
standard requirements.
thelongitudinalaxisofthewoodfibers,andtheforcegenerally
is uniformly distributed throughout the specimen during load-
ing to failure without flexure along its length.
15. Significance and Use
15.1 Thecompressivepropertiesobtainedbyaxialcompres-
sion will provide information similar to that stipulated for
flexural properties in Section 6.
15.2 The compressive properties parallel to grain include
modulus of elasticity (E ), stress at proportional limit,
axial
compressive strength, and strain data beyond proportional
limit.
16. Apparatus
16.1 Testing Machine—Any device having the following is
suitable:
16.1.1 Drive Mechanism—Adrivemechanismforimparting
to a movable loading head a uniform, controlled velocity with
respect to the stationary base.
16.1.2 Load Indicator—A load-indicating mechanism ca-
pable of showing the total compressive force on the specimen.
This force-measuring system shall be calibrated to ensure
accuracy in accordance with Practices E4.
16.2 Bearing Blocks—Bearingblocksshallbeusedtoapply
theloaduniformlyoverthetwocontactsurfacesandtoprevent
eccentric loading on the specimen. At least one spherical
bearing block shall be used to ensure uniform bearing. Spheri-
cal bearing blocks may be used on either or both ends of the
FIG. 5 Example Test Setup for a Short Specimen Compression
specimen, depending on the degree of parallelism of bearing
Parallel to Grain Test (Two Bearing Blocks Illustrated)
surfaces (Fig. 5). The radius of the sphere shall be as small as
practicable,inordertofacilitateadjustmentofthebearingplate
to the specimen, and yet large enough to provide adequate the greatest cross-section dimension. The center of the sphere
spherical bearing area. This radius is usually one to two times shall be on the plane of the specimen contact surface.The size
D198 − 22a
of the compression plate shall be larger than the contact moisture meters or measure more accurately by weights of
surface. It has been found convenient to provide an adjustment samples in accordance with Test Methods D4442.
formovingthespecimenonitsbearingplatewithrespecttothe
18.2 Test Setup:
center of spherical rotation to ensure axial loading.
18.2.1 Bearing Surfaces—After the specimen length has
been calculated in accordance with 18.5, cut the specimen to
16.3 Compressometer:
16.3.1 Gauge Length—For modulus of elasticity theproperlengthsothatthecontactsurfacesareplane,parallel
to each other, and normal to the long axis of the specimen.
calculations, a device shall be provided by which the deforma-
tionofthespecimenismeasuredwithrespecttospecificpaired Furthermore, the axis of the specimen shall be generally
parallel to the fibers of the wood.
gauge points defining the gauge length. To obtain test data
representative of the test material as a whole, such paired
NOTE 5—A sharp fine-toothed saw of either the crosscut or “novelty”
gauge points shall be located symmetrically on the lengthwise
crosscut type has been used satisfactorily for obtaining the proper end
surface of the specimen as far apart as feasible, yet at least one
surfaces. Power equipment with accurate table guides is especially
recommended for this work.
times the larger cross-sectional dimension from each of the
NOTE 6—It is desirable to have failures occur in the body of the
contactsurfaces.Atleasttwopairsofsuchgaugepointsonthe
specimen and not adjacent to the contact surface. Therefore, the cross-
opposite sides of the specimen shall be used to measure the
sectional areas adjacent to the loaded surface may be reinforced.
average deformation.
18.2.2 Centering—First geometrically center the specimens
16.3.2 Accuracy—The device shall be able to measure
on the bearing plates and then adjust the spherical seats so that
changesindeformationtothreesignificantfigures.Sincegauge
the specimen is loaded uniformly and axially.
lengths vary over a wide range, the measuring instruments
18.3 Speed of Testing—The loading shall progress at a
should conform to their appropriate class in accordance with
constant deformation rate such that the average time to
Practice E83.
maximum load for the test series shall be at least 4 min. It is
permissible to initially test a few random specimens from a
17. Compression Specimen
series at an alternate rate as the test rate is refined. Otherwise,
17.1 Material—The test specimen shall consist of a struc-
the selected rate shall be held constant for the test series.
turalmemberthatisgreaterthannominal2in.by2in.(38mm
18.4 Load-Deformation Curves—If load-deformation data
by 38mm) in cross section (see 3.2.7).
have been obtained with a compressometer described in 16.3,
17.2 Identification—Material or materials of the specimen
it shall be permitted to remove the apparatus at any point after
shall be as fully described as for flexure specimens in 8.2.
either the proportional limit or 40 % of the expected average
17.3 Specimen Measurements—The weight and dimensions
maximum load is achieved. Note the load at first failure, at
(length and cross-section) of the specimen, shall be measured
points of sudden change in specimen behavior, and at maxi-
before the test to three significant figures. Sufficient measure-
mum load. If the deformation measurement is continued to
mentsofthecrosssectionshallbemadealongthelengthofthe
failure, then it shall also be recorded at the same points.
specimentodescribeshapecharacteristicsandtodeterminethe
18.5 Records—Record the maximum load, as well as a
smallest section. The physical characteristics of the specimen,
description and sketch of the failure relating the latter to the
as described by its density or specific gravity, shall be
location of imperfections in the specimen. Reexamine the
permitted to be determined in accordance with Test Method
section of the specimen containing the failure during analysis
D2395.
of the data.
17.4 Specimen Description—The inherent imperfections
18.6 Moisture Content Determination—Determine the
and intentional modifications shall be described as for flexure
specimen moisture content in accordance with 9.6.
specimens in 8.4.
19. Calculation
17.5 Specimen Length—Thelengthofthespecimenshallbe
such that the compressive force continues to be uniformly
19.1 Compute physical and mechanical properties in accor-
distributed throughout the specimen during loading—hence no
dance with Terminology E6, and as follows (see compressive
flexureoccurs.Tomeetthisrequirement,thespecimenshallbe
notations):
a short specimen having a maximum length, ℓ, less than 17
19.1.1 Stress at proportional limit, σ' =P'/A in psi (MPa).
c
times the least radius of gyration, r, of the cross section of the
19.1.2 Compressive strength, σ =P /A in psi (MPa).
c max
specimen(seecompressivenotations).Theminimumlengthof
19.1.3 Modulus of elasticity, E =P'/Aε in psi (MPa).
axial
the specimen for stress and strain measurements shall be
greater than three times the larger cross section dimension or
20. Report
about ten times the radius of gyration.
20.1 Report the following information:
20.1.1 Complete identification;
18. Procedure
20.1.2 History of seasoning and conditioning;
18.1 Conditioning—Unless otherwise indicated in the re- 20.1.3 Load apparatus;
search program or material specification, condition the speci- 20.1.4 Deflection apparatus;
men to constant weight so it is at moisture equilibrium, under 20.1.5 Length and cross-section dimensions;
the desired environment. Approximate moisture contents with 20.1.6 Gauge length;
D198 − 22a
20.1.7 Rate of load application;
20.1.8 Computed physical and mechanical properties, in-
cluding specific gravity and moisture content, compressive
strength, stress at proportional limit, modulus of elasticity, and
a statistical measure of variability of these values;
20.1.9 Description of failure; and
20.1.10 Details of any deviations from the prescribed or
recommended methods as outlined in the standard.
COMPRESSION PARALLEL TO GRAIN (CRUSHING
STRENGTH OF LATERALLY SUPPORTED LONG
SPECIMEN, EFFECTIVE ℓ/r≥ 17) FIG. 6 Minimum Spacing of Lateral Supports of Long Compres-
sion Specimens
21. Scope
21.1 This test method covers the determination of the
the sphere shall be as small as practicable, in order to facilitate
compressive properties of structural members when such a
adjustment of the bearing plate to the specimen, and yet large
member has a slenderness ratio (length to least radius of
enough to provide adequate spherical bearing area.This radius
gyration) of more than 17, and when such a member is to be
is usually one to two times the greatest cross-section dimen-
evaluated in full size but with lateral supports that are spaced
sion. The center of the sphere shall be on the plane of the
to produce an effective slenderness ratio, ℓ/r, of less than 17.
specimen contact surface. The size of the compression plate
This test method is intended primarily for structural members
shall be larger than the contact surface.
ofrectangularcrosssectionbutisalsoapplicabletoirregularly
24.3 Lateral Support:
shaped studs, braces, chords, round poles and piles, or special
24.3.1 General—Evaluationofthecrushingstrengthoflong
sections.
compression specimens requires that they be supported later-
ally to prevent buckling during the test without undue pressure
22. Summary of Test Method
against the sides of the specimen. Furthermore, the support
22.1 The compression specimen is subjected to a force
shall not restrain either the longitudinal compressive deforma-
uniformly distributed on the contact surface in a direction
tion or load during test. The support shall be either continuous
generally parallel to the longitudinal axis of the wood fibers,
orintermittent.Intermittentsupportsshallbespacedsothatthe
and the force generally is uniformly distributed throughout the
distance between supports (ℓ or ℓ ) is less than 17 times the
1 2
specimen during loading to failure without flexure along its
least radius of gyration of the cross section.
length.
24.3.2 Rectangular Specimens—The general rules for lat-
eral support outlined in 24.3.1 shall also apply to rectangular
23. Significance and Use
specimens. However, the effective column length as controlled
23.1 Thecompressivepropertiesobtainedbyaxialcompres-
by intermittent support spacing on flatwise face (ℓ ) need not
sion will provide information similar to that stipulated for
equal that on edgewise face (ℓ ). The minimum spacing of the
flexural properties in Section 6.
supports on the flatwise face shall be 17 times the least radius
23.2 The compressive properties parallel to grain include
of gyration of the cross section, which is about the centroidal
modulus of elasticity (E ), stress at proportional limit,
axis parallel to flat face. And the minimum spacing of the
axial
compressive strength, and strain data beyond proportional
supportsontheedgewisefaceshallbe17timestheotherradius
limit.
of gyration (Fig. 6).Asatisfactory method of providing lateral
supportfor2in.nominal(38mm)dimensionstockisshownin
24. Apparatus
Fig.7.A27in.(686mm)I-beamprovidestheframeforthetest
24.1 Testing Machine—Any device having the following is machine. Small I-beams provide reactions for longitudinal
suitable: pressure.Apivoted top I-beam provides lateral support on one
24.1.1 Drive Mechanism—Adrivemechanismforimparting flatwise face, while the web of the large I-beam provides the
to a movable loading head a uniform, controlled velocity with other. In between these steel members, metal guides on 3 in.
respect to the stationary base. (7.6 cm) spacing (hidden from view) attached to plywood
24.1.2 Load Indicator—A load-indicating mechanism ca- fillers provide the flatwise support and contact surface. In
pable of showing the total compressive force on the specimen. betweentheflangesofthe27in.(686mm)I-beam,fingersand
This force-measuring system shall be calibrated to ensure wedges provide edgewise lateral support.
accuracy in accordance with Practices E4.
24.4 Compressometer:
24.2 Bearing Blocks—Bearingblocksshallbeusedtoapply 24.4.1 Gauge Length—For modulus of elasticity (E )
axial
theloaduniformlyoverthetwocontactsurfacesandtoprevent calculations, a device shall be provided by which the deforma-
eccentricloadingonthespecimen.Onesphericalbearingblock tionofthespecimenismeasuredwithrespecttospecificpaired
shall be used to ensure uniform bearing, or a rocker-type gauge points defining the gauge length. To obtain data repre-
bearing block shall be used on each end of the specimen with sentative of the test material as a whole, such paired gauge
their axes of rotation at 0° to each other (Fig. 6).The radius of pointsshallbelocatedsymmetricallyonthelengthwisesurface
D198 − 22a
FIG. 7 Example Test Setup for a Long Specimen Compression Parallel to Grain Test
of the specimen as far apart as feasible, yet at least one times themembershallbetested,exceptfortrimmingorsquaringthe
the larger cross-sectional dimension from each of the contact bearing surface (see 26.2.1).
surfaces. At least two pairs of such gauge points on the
opposite sides of the specimen shall be used to measure the 26. Procedure
average deformation.
26.1 Preliminary—Unless otherwise indicated in the re-
24.4.2 Accuracy—The device shall be able to measure
search program or material specification, condition the speci-
changesindeformationtothreesignificantfigures.Sincegauge
men to constant weight so it is at moisture equilibrium, under
lengths vary over a wide range, the measuring instruments
the desired environment. Moisture contents may be approxi-
should conform to their appropriate class in accordance with
mated with moisture meters or more accurately measured by
Practice E83.
weights of samples in accordance with Test Methods D4442.
26.2 Test Setup:
25. Compression Specimen
26.2.1 Bearing Surfaces—Cut the bearing surfaces of the
25.1 Material—The specimen shall consist of a structural
specimensothatthecontactsurfacesareplane,paralleltoeach
member that is greater than nominal 2in. by 2in. (38mm by
other, and normal to the long axis of the specimen.
38mm) in cross section (see 3.2.7).
26.2.2 Setup Method—After physical measurements have
25.2 Identification—Material or materials of the specimen
been taken and recorded, place the specimen in the testing
shall be as fully described as for flexure specimens in 8.2.
machine between the bearing blocks at each end and between
the lateral supports on the four sides. Center the contact
25.3 Specimen Measurements—The weight and dimensions
(length and cross-section) of the specimen shall be measured surfacesgeometricallyonthebearingplatesandthenadjustthe
spherical seats for full contact. Apply a slight longitudinal
before the test to three significant figures. Sufficient measure-
mentsofthecrosssectionshallbemadealongthelengthofthe pressure to hold the specimen while the lateral supports are
adjusted and fastened to conform to the warp, twist, or bend of
specimentodescribeshapecharacteristicsandtodeterminethe
smallest section. The physical characteristics of the specimen, the specimen.
asdescribedbyitsdensityorspecificgravityshallbepermitted
26.3 Speed of Testing—The loading shall progress at a
to be determined in accordance with Test
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D198 − 22 D198 − 22a
Standard Test Methods of
Static Tests of Lumber in Structural Sizes
This standard is issued under the fixed designation D198; 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.
INTRODUCTION
Numerous evaluations of structural members of sawn lumber have been conducted in accordance
with Test Methods D198. While the importance of continued use of a satisfactory standard should not
be underestimated, the original standard (1927) was designed primarily for sawn lumber material, such
as bridge stringers and joists. With the advent of structural glued laminated (glulam) timbers, structural
composite lumber, prefabricated wood I-joists, and even reinforced and prestressed timbers, a
procedure adaptable to a wider variety of wood structural members was required and Test Methods
D198 has been continuously updated to reflect modern usage.
The present standard provides a means to evaluate the flexure, compression, tension, and torsion
strength and stiffness of lumber and wood-based products in structural sizes. A flexural test to evaluate
the shear stiffness is also provided. In general, the goal of the D198 test methods is to provide a
reliable and repeatable means to conduct laboratory tests to evaluate the mechanical performance of
wood-based products. While many of the properties tested using these methods may also be evaluated
using the field procedures of Test Methods D4761, the more detailed D198 test methods are intended
to establish practices that permit correlation of results from different sources through the use of more
uniform procedures. The D198 test methods are intended for use in scientific studies, development of
design values, quality assurance, or other investigations where a more accurate test method is desired.
Provision is made for varying the procedure to account for special problems.
1. Scope
1.1 These test methods cover the evaluation of lumber and wood-based products in structural sizes by various testing procedures.
1.2 The test methods appear in the following order:
Sections
Flexure 4 – 11
Compression (Short Specimen) 13 – 20
Compression (Long Specimen) 21 – 28
Tension 29 – 36
Torsion 37 – 44
Shear Modulus 45 – 52
1.3 Notations and symbols relating to the various testing procedures are given in Appendix X1.
These test methods are under the jurisdiction of ASTM Committee D07 on Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental Test Methods
and Properties.
Current edition approved Aug. 1, 2022Oct. 1, 2022. Published August 2022October 2022. Originally approved in 1924. Last previous edition approved in 20212022 as
D198 – 21a.22. DOI: 10.1520/D0198-22.10.1520/D0198-22a.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D198 − 22a
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses 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 appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
D9 Terminology Relating to Wood and Wood-Based Products
D1165 Nomenclature of Commercial Hardwoods and Softwoods
D2395 Test Methods for Density and Specific Gravity (Relative Density) of Wood and Wood-Based Materials
D2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
D3737 Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
D4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
D4761 Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
D7438 Practice for Field Calibration and Application of Hand-Held Moisture Meters
E4 Practices for Force Calibration and Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E83 Practice for Verification and Classification of Extensometer Systems
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2309 Practices for Verification of Displacement Measuring Systems and Devices Used in Material Testing Machines
3. Terminology
3.1 Definitions—See Terminology E6, Terminology D9, and Nomenclature D1165.
3.2 Definitions:Definitions of Terms Specific to This Standard:
3.2.1 composite wood member—a laminar construction comprising a combination of wood and other simple or complex materials
assembled and intimately fixed in relation to each other so as to use the properties of each to attain specific structural advantage
for the whole assembly.
FIG. 1 Flexure Test Method—Example of Two-Point Loading
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D198 − 22a
3.2.2 depth (d)—the dimension of the flexure specimen or shear modulus specimen that is perpendicular to the span and parallel
to the direction in which the load is applied (Fig. 1).
3.2.3 shear span—two times the distance between a reaction and the nearest load point for a symmetrically loaded flexure
specimen (Fig. 1).
3.2.4 shear span-depth ratio—the numerical ratio of shear span divided by depth of a flexure specimen.
3.2.5 span (ℓ)—the total distance between reactions on which a flexure specimen or shear modulus specimen is supported to
accommodate a transverse load (Fig. 1).
3.2.6 span-depth ratio (ℓ/d)—the numerical ratio of total span divided by depth of a flexure specimen or shear modulus specimen.
3.2.7 structural member—sawn lumber, glulam, structural composite lumber, prefabricated wood I-joists, or other similar product
for which strength or stiffness, or both, are primary criteria for the intended application and which usually are used in full length
and in cross-sectional sizes greater than nominal 2 by 2 in. (38 by 38 mm). 2 in. by 2 in. (38 mm by 38 mm).
FLEXURE
4. Scope
4.1 This test method covers the determination of the flexural properties of structural members. This test method is intended
primarily for members with rectangular cross sections but is also applicable to members with round and irregular shapes, such as
round posts, pre-fabricated wood I-joists, or other special sections.
5. Summary of Test Method
5.1 The flexure specimen is subjected to a bending moment by supporting it near its ends, at locations called reactions, and
applying transverse loads symmetrically imposed between these reactions. The specimen is deflected at a prescribed rate until
failure occurs. Coordinated observations of loads and deflections are made.
6. Significance and Use
6.1 The flexural properties established by this test method provide:
6.1.1 Data for use in development of grading rules and specifications;
6.1.2 Data for use in development of design values for structural members;
6.1.3 Data on the influence of imperfections on mechanical properties of structural members;
6.1.4 Data on strength properties of different species or grades in various structural sizes;
6.1.5 Data for use in checking existing equations or hypotheses relating to the structural behavior;
6.1.6 Data on the effects of chemical or environmental conditions on mechanical properties;
6.1.7 Data on effects of fabrication variables such as depth, taper, notches, or type of end joint in laminations; and
6.1.8 Data on relationships between mechanical and physical properties.
6.2 Procedures are described here in sufficient detail to permit duplication in different laboratories so that comparisons of results
from different sources will be valid. Where special circumstances require deviation from some details of these procedures, these
deviations shall be carefully described in the report (see Section 11).
D198 − 22a
7. Apparatus
7.1 Testing Machine—A device that provides (1) a rigid frame to support the specimen yet permit its deflection without restraint,
(2) a loading head through which the force is applied without high-stress concentrations in the specimen, and (3) a force-measuring
device that is calibrated to ensure accuracy in accordance with Practices E4.
7.2 Support Apparatus—Devices that provide support of the specimen at the specified span.
7.2.1 Reaction Bearing Plates—The specimen shall be supported by metal bearing plates to prevent damage to the specimen at
the point of contact with the reaction support (Fig. 1). The plates shall be of sufficient length, thickness, and width to provide a
firm bearing surface and ensure a uniform bearing stress across the width of the specimen.
7.2.2 Reaction Supports—The bearing plates shall be supported by devices that provide unrestricted longitudinal deformation and
rotation of the specimen at the reactions due to loading. Provisions shall be made to restrict horizontal translation of the specimen
(see 7.3.1 and Appendix X5).
7.2.3 Reaction Bearing Alignment—Provisions shall be made at the reaction supports to allow for initial twist in the length of the
specimen. If the bearing surfaces of the specimen at its reactions are not parallel, then the specimen shall be shimmed or the
individual bearing plates shall be rotated about an axis parallel to the span to provide full bearing across the width of the specimen.
Supports with lateral self-alignment are normally used (Fig. 2).
7.2.4 Lateral Support—Specimens that have a depth-to-width ratio (d/b) of three or greater are subject to out-of-plane lateral
instability during loading and require lateral support. Lateral support shall be provided at points located about halfway between
a reaction and a load point. Additional supports shall be permitted as required to prevent lateral-torsional buckling. Each support
shall allow vertical movement without frictional restraint but shall restrict lateral displacement (Fig. 3).
7.3 Load Apparatus—Devices that transfer load from the testing machine at designated points on the specimen. Provisions shall
be made to prevent eccentric loading of the load measuring device (see Appendix X5).
7.3.1 Load Bearing Blocks—The load shall be applied through bearing blocks (Fig. 1), which are of sufficient thickness and
extending entirely across the specimen width to eliminate high-stress concentrations at places of contact between the specimen and
bearing blocks. Load shall be applied to the blocks in such a manner that the blocks shall be permitted to rotate about an axis
FIG. 2 Example of Bearing Plate (A), Rollers (B), and Reaction-Alignment-Rocker (C), for Small Flexure Specimens
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FIG. 3 Example of Lateral Support for Long, Deep Flexure Specimens
perpendicular to the span (Fig. 4). To prevent specimen deflection without restraint in case of two-point loading, metal bearing
plates and rollers shall be used in conjunction with one or both load-bearing blocks, depending on the reaction support conditions
(see Appendix X5). Provisions such as rotatable bearings or shims shall be made to ensure full contact between the specimen and
the loading blocks. The size and shape of these loading blocks, plates, and rollers may vary with the size and shape of the specimen,
as well as for the reaction bearing plates and supports. For rectangular structural products, the loading surface of the blocks shall
have a radius of curvature equal to two to four times the specimen depth. Specimens having circular or irregular cross-sections
shall have bearing blocks that distribute the load uniformly to the bearing surface and permit unrestrained deflections.
7.3.2 Load Points—Location of load points relative to the reactions depends on the purpose of testing and shall be recorded (see
Appendix X5).
7.3.2.1 Two-Point Loading—The total load on the specimen shall be applied equally at two points equidistant from the reactions.
The two load points will normally be at a distance from their reaction equal to one third of the span (ℓ/3) (third-point loading),
but other distances shall be permitted for special purposes.
FIG. 4 Example of Curved Loading Block (A), Load-Alignment Rocker (B), Roller-Curved Loading Block (C), Load Evener (D), and
Deflection-Measuring Apparatus (E)
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7.3.2.2 Center-Point Loading—A single load shall be applied at mid-span.
7.3.2.3 For evaluation of shear properties, center-point loading or two-point loading shall be used (see Appendix X5).
7.4 Deflection-Measuring Apparatus:
7.4.1 General—For modulus of elasticity calculations, devices shall be provided by which the deflection of the neutral axis of the
specimen at the center of the span is measured with respect to a straight line joining two reference points equidistant from the
reactions and on the neutral axis of the specimen.
7.4.1.1 The apparent modulus of elasticity (E ) shall be calculated using the full-span deflection (Δ). The reference points for
app
the full-span deflection measurements shall be positioned such that a line perpendicular to the neutral axis at the location of the
reference point, passes through the support’s center of rotation.
7.4.1.2 The true or shear-free modulus of elasticity (E ) shall be calculated using the shear-free deflection. The reference points
sf
for the shear-free deflection measurements shall be positioned at cross-sections free of shear and stress concentrations (see
Appendix X5).
NOTE 1—The apparent modulus of elasticity (E ) may be converted to the shear-free modulus of elasticity (E ) by calculation, assuming that the shear
app sf
modulus (G) is known. See Appendix X2.
7.4.2 Wire Deflectometer—A wire stretched taut between two nails, smooth dowels, or other rounded fixtures attached to the
neutral axis of the specimen directly above the reactions and extending across a scale attached at the neutral axis of the specimen
at mid-span shall be permitted to read deflections with a telescope or reading glass to magnify the area where the wire crosses the
scale. When a reading glass is used, a reflective surface placed adjacent to the scale will help to avoid parallax.
7.4.3 Yoke Deflectometer—A satisfactory device commonly used to measure deflection of the center of the specimen with respect
to any point along the neutral axis consists of a lightweight U-shaped yoke suspended between nails, smooth dowels, or other
rounded fixtures attached to the specimen at its neutral axis. An electronic displacement gauge, dial micrometer, or other suitable
measurement device attached to the center of the yoke shall be used to measure vertical displacement at mid-span relative to the
specimen’s neutral axis (Fig. 4).
7.4.4 Alternative Deflectometers—Deflectometers that do not conform to the general requirements of 7.4.1 shall be permitted
provided the mean deflection measurements are not significantly different from those devices conforming to 7.4.1. The equivalency
of such devices to deflectometers, such as those described in 7.4.2 or 7.4.3, shall be documented and demonstrated by comparison
testing.
NOTE 2—Where possible, equivalency testing should be undertaken in the same type of product and stiffness range for which the device will be used.
Issues that should be considered in the equivalency testing include the effect of crushing at and in the vicinity of the load and reaction points, twist in
the specimen, and natural variation in properties within a specimen.
7.4.5 Accuracy—The deflection measurement devices and recording system shall be capable of at least a Class B rating when
evaluated in accordance with Practice E2309.
8. Flexure Specimen
8.1 Material—The flexure specimen shall consist of a structural member.
8.2 Identification—Material or materials of the specimen shall be identified as fully as possible by including the origin or source
of supply, species, and history of drying and conditioning, chemical treatment, fabrication, and other pertinent physical or
mechanical details that potentially affect the strength or stiffness. Details of this information shall depend on the material or
materials in the structural member. For example, wood beams or joists would be identified by the character of the wood, that is,
species, source, and so forth, whereas structural composite lumber would be identified by the grade, species, and source of the
material (that is, product manufacturer, manufacturing facility, etc.).
8.3 Specimen Measurements—The weight and dimensions (length and cross-section) of the specimen shall be measured before the
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test to three significant figures. Sufficient measurements of the cross section shall be made along the length to describe the width
and depth of rectangular specimens and to determine the critical section or sections of non-uniform (or non-prismatic) specimens.
The physical characteristics of the specimen as described by its density or specific gravity shall be permitted to be determined in
accordance with Test Methods D2395.
8.4 Specimen Description—The inherent strength-reducing characteristics or intentional modifications of the composition of the
specimen shall be fully described by recording the size and location of such factors including, but not limited to, knots, checks,
and reinforcements. Size and location of intentional modifications such as placement of laminations, glued joints, and
reinforcements shall be recorded during the fabrication process or prior to testing. Where required by the test objectives for
materials with discrete strength-reducing characteristics or intentional modifications, sketch or photographic records shall be made
of each face and the ends. These sketches or photographs shall show the size, location, and type of strength-reducing characteristics
or intentional modifications, including: reinforcements, glued joints, slope of grain, knots, distribution of sapwood and heartwood,
location of pitch pockets, direction of annual rings, and such abstract factors as crook, bow, cup, twist, which might affect the
flexural strength. Where required by the test objectives, the surface features of each specimen shall be described in sufficient detail
to deduce the extent of the strength-reducing characteristics within the cross section.
8.5 Rules for Determination of Specimen Length—The cross-sectional dimensions of structural products usually have established
sizes, depending upon the manufacturing process and intended use, so that no modification of these dimensions is involved. The
length, however, will be established by the type of data desired (see Appendix X5). The span length is determined from knowledge
of specimen depth, the distance between load points, as well as the type and orientation of material in the specimen. The total
specimen length includes the span (measured from center to center of the reaction supports) and the length of the overhangs
(measured from the center of the reaction supports to the ends of the specimen). Sufficient length shall be provided so that the
specimen can accommodate the bearing plates and rollers and will not slip off the reactions during test.
8.5.1 For the evaluation of flexural strength, the overhang beyond the span shall be minimized, as the measured flexural capacity
is influenced by the length of the overhang. The reaction bearing plates shall be at least long enough to prevent bearing failures.
The specimen overhang beyond the test span shall not extend by more than four times the member depth. If longer overhangs are
necessary to satisfy the test objectives, the length of overhang shall be reported, and the calculated bending strength shall be
reduced to account for the weight of the overhangs. The original bending strength, the overhang-adjusted bending strength, and
the method of adjustment shall be reported.
8.5.2 For evaluation of shear properties, the overhang beyond the span shall be minimized, as the shear capacity is influenced by
the length of the overhang. The reaction bearing plates shall be the minimum length necessary to prevent bearing failures. The
specimen shall not extend beyond the end of the reaction plates (Fig. X5.3 in Appendix X5) unless longer overhangs are required
to simulate a specific design condition.
9. Procedure
9.1 Conditioning—Unless otherwise indicated in the research program or material specification, condition the specimen to
constant weight so it is in moisture equilibrium under the desired environmental conditions. Approximate moisture contents with
moisture meters or measure more accurately by weights of samples in accordance with Test Methods D4442.
9.2 Test Setup—Determine the size of the specimen, the span, and the shear span in accordance with 7.3.2 and 8.5. Locate the
flexure specimen symmetrically on its supports with load bearing and reaction bearing blocks as described in 7.2 – 7.4. The
specimen shall be adequately supported laterally in accordance with 7.2.4. Set apparatus for measuring deflections in place (see
7.4). Full contact shall be attained between support bearings, loading blocks, and the specimen surface.
9.3 Speed of Testing—The loading shall progress at a constant deformation rate such that the average time to maximum load for
the test series shall be at least 4 min. It is permissible to initially test a few random specimens from a series at an alternate rate
as the test rate is refined. Otherwise, the selected rate shall be held constant for the test series.
9.4 Load-Deflection Curves:
9.4.1 Obtain load-deflection data with apparatus described in 7.4.1. When the objective of the deflection measurement is only to
determine the specimen stiffness or modulus of elasticity, it shall be permitted to remove the deflection-measuring apparatus at any
point after either the proportional limit or 40 % of the expected average maximum load is achieved. Note the load at first failure,
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at the maximum load, and at points of sudden change in specimen behavior. If the deflection measurement is continued to failure,
then it shall also be recorded at the same points. Continue loading until complete failure or an arbitrary terminal load has been
reached.
9.4.2 If an additional deflection-measuring apparatus is provided to measure the shear-free deflection (Δ ) over a second distance
sf
(ℓ ) in accordance with 7.4.1.2, such load-deflection data shall be obtained until either the proportional limit or 40 % of the
sf
expected average maximum load are achieved.
9.5 Record of Failures—Describe failures in detail as to type, manner, and order of occurrence, and position in the specimen.
Record descriptions of the failures and relate them to specimen drawings or photographs referred to in 8.4. Also record notations
as the order of their occurrence on such references. Hold the section of the specimen containing the failure for examination and
reference until analysis of the data has been completed.
9.6 Moisture Content Determination—Following the test, measure the moisture content of the specimen at a location away from
the end and as close to the failure zone as practical in accordance with the procedures outlined in Test Methods D4442.
Alternatively, the moisture content for a wood specimen shall be permitted to be determined using a calibrated moisture meter
according to Standard Practice D7438. The number of moisture content samples shall be determined using Practice D7438
guidelines, with consideration of the expected moisture content variability, and any related requirements in the referenced product
standards.
10. Calculation
10.1 Compute physical and mechanical properties and their appropriate adjustments for the specimen in accordance with the
relationships in Appendix X2.
11. Report
11.1 Report the following information:
11.1.1 Complete identification of the specimen, including species, origin, shape and form, fabrication procedure, type and location
of imperfections or reinforcements, and pertinent physical or chemical characteristics relating to the quality of the material,
11.1.2 History of seasoning and conditioning,
11.1.3 Loading conditions to portray the load and support mechanics, including type of equipment, lateral supports, if used, the
location of load points relative to the reactions, the size of load bearing blocks, reaction bearing plates, clear distances between
load block and reaction plate and between load blocks, and the size of overhangs, if present,
11.1.4 Deflection apparatus,
11.1.5 Depth and width of the specimen or pertinent cross-sectional dimensions,
11.1.6 Span length and shear span distance,
11.1.7 Rate of load application,
11.1.8 Computed physical and mechanical properties, including specific gravity or density (as applicable) and moisture content,
flexural strength, stress at proportional limit, modulus of elasticity, calculation methods (Note 3), and a statistical measure of
variability of these values,
NOTE 3—Appendix X2 provides acceptable formulae and guidance for determining the flexural properties.
11.1.9 Description of failure, and
11.1.10 Details of any deviations from the prescribed or recommended methods as outlined in the standard.
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12. Precision and Bias
12.1 Interlaboratory Test Program—An interlaboratory study (ILS) was conducted in 2006–2007 by sixteen laboratories in the
United States and Canada in accordance with Practice E691. The scope of this study was limited to the determination of the
apparent modulus of elasticity of three different 2 × 4 nominal sized products tested both edgewise and flatwise. The deflection of
each flexure specimen’s neutral axis at the mid-span was measured with a yoke according to 7.4. Five specimens of each product
were tested in a round-robin fashion in each laboratory, with four test results obtained for each specimen and test orientation. The
resulting precision indexes are shown in Table 1. For further discussion, see Appendix X5.4.
12.2 The terms of repeatability and reproducibility are used as specified in Practice E177.
12.3 Bias—The bias is not determined because the apparent modulus of elasticity is defined in terms of this method, which is
generally accepted as a reference (Note 4).
NOTE 4—Use of this method does not necessarily eliminate laboratory bias or ensure a level of consistency necessary for establishing reference values.
The users are encouraged to participate in relevant interlaboratory studies (that is, an ILS involving sizes and types of product similar to those regularly
tested by the laboratory) to provide evidence that their implementation of the Test Method provides levels of repeatability and reproducibility at least
comparable to those shown in Table 1. See also X5.4.2 and X5.4.3.
COMPRESSION PARALLEL TO GRAIN (SHORT SPECIMEN, NO LATERAL SUPPORT, ℓ/r < 17)
13. Scope
13.1 This test method covers the determination of the compressive properties of specimens taken from structural members when
such a specimen has a slenderness ratio (length to least radius of gyration) of less than 17. The method is intended primarily for
structural members with rectangular cross sections, but is also applicable to irregularly shaped studs, braces, chords, round poles,
or special sections.
A
TABLE 1 Test Materials, Configurations, and Precision Indexes
Average
Repeatability Reproducibility
Apparent
Width × Depth Span Test Repeatability Reproducibility
Limits Limits
Modulus of
Product Test Orientation b × d ! Coefficient of Variation Coefficient of Variation
Elasticity
in. (mm) in. (mm) CV CV
r R
E
app
2CV d2CV 2CV d2CV
r r R R
psi × 10 (GPa)
Edgewise 1.5 × 3.5 63.0 2.17 1.4 % 2.0 % 2.7 % 3.8 % 4.0 % 5.6 %
(38 × 89) (1600) (14.9)
A
Flatwise 3.5 × 1.5 31.5 2.18 1.4 % 3.3 % 2.7 % 3.9 % 6.5 % 9.2 %
(89 × 38) (800) (15.0)
Edgewise 1.5 × 3.5 63.0 1.49 1.0 % 2.1 % 2.0 % 2.8 % 4.2 % 5.9 %
(38 × 89) (1600) (10.3)
B
Flatwise 3.5 × 1.5 31.5 1.54 1.3 % 2.7 % 2.6 % 3.6 % 5.3 % 7.5 %
(89 × 38) (800) (10.6)
Edgewise 1.5 × 3.5 63.0 2.35 1.3 % 2.0 % 2.5 % 3.5 % 3.9 % 5.5 %
(38 × 89) (1600) (16.2)
C
Flatwise 3.5 × 1.5 31.5 2.78 1.5 % 4.3 % 2.9 % 4.2 % 8.3 % 11.8 %
(89 × 38) (800) (19.2)
Edgewise 1.5 × 3.5 63.0 . . . 1.2 % 2.1 % 2.4 % 3.4 % 4.0 % 5.7 %
(38 × 89) (1600)
All Data
Flatwise 3.5 × 1.5 31.5 . . . 1.4 % 3.4 % 2.7 % 3.9 % 6.7 % 9.5 %
(89 × 38) (800)
A
The precision indexes are the average values of five specimens tested in eleven laboratories which were found to be in statistical control and in compliance with the
standard requirements.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR: RR:D07-1005. Contact ASTM Customer
Service at [e-mail].
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14. Summary of Test Method
14.1 The specimen is subjected to a force uniformly distributed on the contact surface in a direction generally parallel to the
longitudinal axis of the wood fibers, and the force generally is uniformly distributed throughout the specimen during loading to
failure without flexure along its length.
15. Significance and Use
15.1 The compressive properties obtained by axial compression will provide information similar to that stipulated for flexural
properties in Section 6.
15.2 The compressive properties parallel to grain include modulus of elasticity (E ), stress at proportional limit, compressive
axial
strength, and strain data beyond proportional limit.
16. Apparatus
16.1 Testing Machine—Any device having the following is suitable:
16.1.1 Drive Mechanism—A drive mechanism for imparting to a movable loading head a uniform, controlled velocity with respect
to the stationary base.
16.1.2 Load Indicator—A load-indicating mechanism capable of showing the total compressive force on the specimen. This
force-measuring system shall be calibrated to ensure accuracy in accordance with Practices E4.
16.2 Bearing Blocks—Bearing blocks shall be used to apply the load uniformly over the two contact surfaces and to prevent
eccentric loading on the specimen. At least one spherical bearing block shall be used to ensure uniform bearing. Spherical bearing
blocks may be used on either or both ends of the specimen, depending on the degree of parallelism of bearing surfaces (Fig. 5).
The radius of the sphere shall be as small as practicable, in order to facilitate adjustment of the bearing plate to the specimen, and
yet large enough to provide adequate spherical bearing area. This radius is usually one to two times the greatest cross-section
dimension. The center of the sphere shall be on the plane of the specimen contact surface. The size of the compression plate shall
be larger than the contact surface. It has been found convenient to provide an adjustment for moving the specimen on its bearing
plate with respect to the center of spherical rotation to ensure axial loading.
16.3 Compressometer:
16.3.1 Gauge Length—For modulus of elasticity calculations, a device shall be provided by which the deformation of the specimen
is measured with respect to specific paired gauge points defining the gauge length. To obtain test data representative of the test
material as a whole, such paired gauge points shall be located symmetrically on the lengthwise surface of the specimen as far apart
as feasible, yet at least one times the larger cross-sectional dimension from each of the contact surfaces. At least two pairs of such
gauge points on the opposite sides of the specimen shall be used to measure the average deformation.
16.3.2 Accuracy—The device shall be able to measure changes in deformation to three significant figures. Since gauge lengths
vary over a wide range, the measuring instruments should conform to their appropriate class in accordance with Practice E83.
17. Compression Specimen
17.1 Material—The test specimen shall consist of a structural member that is greater than nominal 2 by 2 in. (38 by 38 mm) 2 in.
by 2 in. (38 mm by 38 mm) in cross section (see 3.2.7).
17.2 Identification—Material or materials of the specimen shall be as fully described as for flexure specimens in 8.2.
17.3 Specimen Measurements—The weight and dimensions (length and cross-section) of the specimen, shall be measured before
the test to three significant figures. Sufficient measurements of the cross section shall be made along the length of the specimen
to describe shape characteristics and to determine the smallest section. The physical characteristics of the specimen, as described
by its density or specific gravity, shall be permitted to be determined in accordance with Test Method D2395.
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FIG. 5 Example Test Setup for a Short Specimen Compression Parallel to Grain Test (Two Bearing Blocks Illustrated)
17.4 Specimen Description—The inherent imperfections and intentional modifications shall be described as for flexure specimens
in 8.4.
17.5 Specimen Length—The length of the specimen shall be such that the compressive force continues to be uniformly distributed
throughout the specimen during loading—hence no flexure occurs. To meet this requirement, the specimen shall be a short
specimen having a maximum length, ℓ, less than 17 times the least radius of gyration, r, of the cross section of the specimen (see
compressive notations). The minimum length of the specimen for stress and strain measurements shall be greater than three times
the larger cross section dimension or about ten times the radius of gyration.
18. Procedure
18.1 Conditioning—Unless otherwise indicated in the research program or material specification, condition the specimen to
constant weight so it is at moisture equilibrium, under the desired environment. Approximate moisture contents with moisture
meters or measure more accurately by weights of samples in accordance with Test Methods D4442.
18.2 Test Setup:
18.2.1 Bearing Surfaces—After the specimen length has been calculated in accordance with 18.5, cut the specimen to the proper
length so that the contact surfaces are plane, parallel to each other, and normal to the long axis of the specimen. Furthermore, the
axis of the specimen shall be generally parallel to the fibers of the wood.
NOTE 5—A sharp fine-toothed saw of either the crosscut or “novelty” crosscut type has been used satisfactorily for obtaining the proper end surfaces.
Power equipment with accurate table guides is especially recommended for this work.
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NOTE 6—It is desirable to have failures occur in the body of the specimen and not adjacent to the contact surface. Therefore, the cross-sectional areas
adjacent to the loaded surface may be reinforced.
18.2.2 Centering—First geometrically center the specimens on the bearing plates and then adjust the spherical seats so that the
specimen is loaded uniformly and axially.
18.3 Speed of Testing—The loading shall progress at a constant deformation rate such that the average time to maximum load for
the test series shall be at least 4 min. It is permissible to initially test a few random specimens from a series at an alternate rate
as the test rate is refined. Otherwise, the selected rate shall be held constant for the test series.
18.4 Load-Deformation Curves—If load-deformation data have been obtained with a compressometer described in 16.3, it shall
be permitted to remove the apparatus at any point after either the proportional limit or 40 % of the expected average maximum
load is achieved. Note the load at first failure, at points of sudden change in specimen behavior, and at maximum load. If the
deformation measurement is continued to failure, then it shall also be recorded at the same points.
18.5 Records—Record the maximum load, as well as a description and sketch of the failure relating the latter to the location of
imperfections in the specimen. Reexamine the section of the specimen containing the failure during analysis of the data.
18.6 Moisture Content Determination—Determine the specimen moisture content in accordance with 9.6.
19. Calculation
19.1 Compute physical and mechanical properties in accordance with Terminology E6, and as follows (see compressive
notations):
19.1.1 Stress at proportional limit, σ' =P'/A in psi (MPa).
c
19.1.2 Compressive strength, σ =P /A in psi (MPa).
c max
19.1.3 Modulus of elasticity, E =P'/Aε in psi (MPa).
axial
20. Report
20.1 Report the following information:
20.1.1 Complete identification;
20.1.2 History of seasoning and conditioning;
20.1.3 Load apparatus;
20.1.4 Deflection apparatus;
20.1.5 Length and cross-section dimensions;
20.1.6 Gauge length;
20.1.7 Rate of load application;
20.1.8 Computed physical and mechanical properties, including specific gravity and moisture content, compressive strength, stress
at proportional limit, modulus of elasticity, and a statistical measure of variability of these values;
20.1.9 Description of failure; and
20.1.10 Details of any deviations from the prescribed or recommended methods as outlined in the standard.
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COMPRESSION PARALLEL TO GRAIN (CRUSHING STRENGTH OF LATERALLY SUPPORTED LONG
SPECIMEN, EFFECTIVE ℓ/r≥ 17)
21. Scope
21.1 This test method covers the determination of the compressive properties of structural members when such a member has a
slenderness ratio (length to least radius of gyration) of more than 17, and when such a member is to be evaluated in full size but
with lateral supports that are spaced to produce an effective slenderness ratio, ℓ/r, of less than 17. This test method is intended
primarily for structural members of rectangular cross section but is also applicable to irregularly shaped studs, braces, chords,
round poles and piles, or special sections.
22. Summary of Test Method
22.1 The compression specimen is subjected to a force uniformly distributed on the contact surface in a direction generally parallel
to the longitudinal axis of the wood fibers, and the force generally is uniformly distributed throughout the specimen during loading
to failure without flexure along its length.
23. Significance and Use
23.1 The compressive properties obtained by axial compression will provide information similar to that stipulated for flexural
properties in Section 6.
23.2 The compressive properties parallel to grain include modulus of elasticity (E ), stress at proportional limit, compressive
axial
strength, and strain data beyond proportional limit.
24. Apparatus
24.1 Testing Machine—Any device having the following is suitable:
24.1.1 Drive Mechanism—A drive mechanism for imparting to a movable loading head a uniform, controlled velocity with respect
to the stationary base.
24.1.2 Load Indicator—A load-indicating mechanism capable of showing the total compressive force on the specimen. This
force-measuring system shall be calibrated to ensure accuracy in accordance with Practices E4.
24.2 Bearing Blocks—Bearing blocks shall be used to apply the load uniformly over the two contact surfaces and to prevent
eccentric loading on the specimen. One spherical bearing block shall be used to ensure uniform bearing, or a rocker-type bearing
block shall be used on each end of the specimen with their axes of rotation at 0° to each other (Fig. 6). The radius of the sphere
shall be as small as practicable, in order to facilitate adjustment of the bearing plate to the specimen, and yet large enough to
provide adequate spherical bearing area. This radius is usually one to two times the greatest cross-section dimension. The center
of the sphere shall be on the plane of the specimen contact surface. The size of the compression plate shall be larger than the contact
surface.
FIG. 6 Minimum Spacing of Lateral Supports of Long Compression Specimens
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24.3 Lateral Support:
24.3.1 General—Evaluation of the crushing strength of long compression specimens requires that they be supported laterally to
prevent buckling during the test without undue pressure against the sides of the specimen. Furthermore, the support shall not
restrain either the longitudinal compressive deformation or load during test. The support shall be either continuous or intermittent.
Intermittent supports shall be spaced so that the distance between supports (ℓ or ℓ ) is less than 17 times the least radius of
1 2
gyration of the cross section.
24.3.2 Rectangular Specimens—The general rules for lateral support outlined in 24.3.1 shall also apply to rectangular specimens.
However, the effective column length as controlled by intermittent support spacing on flatwise face (ℓ ) need not equal that on
edgewise face (ℓ ). The minimum spacing of the supports on the flatwise face shall be 17 times the least radius of gyration of the
cross section, which is about the centroidal axis parallel to flat face. And the minimum spacing of the supports on the edgewise
face shall be 17 times the other radius of gyration (Fig. 6). A satisfactory method of providing lateral support for 2 in. nominal
(38 mm) dimension stock is shown in Fig. 7. A 27 in. (686 mm) I-beam provides the frame for the test machine. Small I-beams
provide reactions for longitudinal pressure. A pivoted top I-beam provides lateral support on one flatwise face, while the web of
the large I-beam provides the other. In between these steel members, metal guides on 3 in. (7.6 cm) spacing (hidden from view)
attached to plywood fillers provide the flatwise support and contact surface. In between the flanges of the 27 in. (686 mm) I-beam,
fingers and wedges provide edgewise lateral support.
24.4 Compressometer:
24.4.1 Gauge Length—For modulus of elasticity (E ) calculations, a device shall be provided by which the deformation of the
axial
specimen is measured with respect to specific paired gauge points defining the gauge length. To obtain data representative of the
test material as a whole, such paired gauge points shall be located symmetrically on the lengthwise surface of the specimen as far
apart as feasible, yet at least one times the larger cross-sectional dimension from each of the contact surfaces. At least two pairs
of such gauge points on the opposite sides of the specimen shall be used to measure the average deformation.
24.4.2 Accuracy—The device shall be able to measure changes in deformation to three significant figures. Since gauge lengths
vary over a wide range, the measuring instruments should conform to their appropriate class in accordance with Practice E83.
25. Compression Specimen
25.1 Material—The specimen shall consist of a structural member that is greater than nominal 2 by 2 in. (38 by 38 mm) 2 in. by
2 in. (38 mm by 38 mm) in cross section (see 3.2.7).
FIG. 7 Example Test Setup for a Long Specimen Compression Parallel to Grain Test
D198 − 22a
25.2 Identification—Material or materials of the specimen shall be as fully described as for flexure specimens in 8.2.
25.3 Specimen Measurements—The weight and dimensions (length and cross-section) of the specimen shall be measured before
the test to three significant figures. Sufficient measurements of the cross section shall be made along the length of the specimen
to describe shape characteristics and to determine the smallest section. The physical characteristics o
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