ASTM D4761 - 25 木材及木质结构材料力学性能的标准试验方法

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Designation: D4761 −25

Standard Test Methods for

Mechanical Properties of Lumber and Wood-Based

Structural Materials

This standard is issued under the ﬁxed designation D4761; 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 the mechanical properties of wood-based structural materials have been

satisfactorily conducted since the late 1920s, using Test Methods D198. Those methods are best suited

to a laboratory environment and are adaptable to a variety of products such as stress-graded lumber,

sawn timber, laminated timbers, wood-plywood composite members, reinforced and pre-stressed

timbers.

The procedures presented in these test methods have been derived from those set forth in Test

Methods D198. They are intended primarily for application to stress-graded lumber, but can be used

for other wood-based structural materials as well. The procedures are more ﬂexible than those in Test

Methods D198, making testing in a non-laboratory environment more feasible. Thus the test methods

can be used on production sites for ﬁeld testing and quality control, as well as in laboratories for

research applications. Key differences from Test Methods D198 are the testing speed, the deﬂection-

measuring procedures for specimens under load, and the detail of data reporting. Furthermore, the test

methods do not require that specimens be loaded to failure.

Since these test methods allow latitude in testing procedures, the procedures used shall be fully

documented in the test report. It may also be desirable to correlate the results from tests carried out

according to these test methods with test results obtained using a traditional procedure, such as that

set forth in Test Methods D198.

1. Scope

1.1 These test methods cover the determination of the

mechanical properties of stress-graded lumber and other wood-

based structural materials.

1.2 These test methods appear in the following order:

Section

Bending edge-wise 6

Bending ﬂat-wise:

Center-point loading 7

Third-point loading 8

Axial strength in tension 9

Axial strength in compression 10

1.3 Units—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.

1.4 This standard does not purport to address all of the

safety concerns, if any, associated with its use. It is the

responsibility of the user of this standard to establish appro-

priate safety, health, and environmental practices and deter-

mine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accor-

dance with internationally recognized principles on standard-

ization established in the Decision on Principles for the

Development of International Standards, Guides and Recom-

mendations issued by the World Trade Organization Technical

Barriers to Trade (TBT) Committee.

2. Referenced Documents

2.1 ASTM Standards:

D9 Terminology Relating to Wood and Wood-Based Prod-

ucts

D198 Test Methods of Static Tests of Lumber in Structural

Sizes

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 Oct. 15, 2025. Published October 2025. Originally

approved in 1988. Last previous edition approved in 2019 as D4761 – 19. DOI:

10.1520/D4761-25.

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

contact ASTM Customer Service at www.astm.org/contact. For Annual Book of

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

page on the ASTM website.

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

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

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D245 Practice for Establishing Structural Grades and Re-

lated Allowable Properties for Visually Graded Lumber

D1990 Practice for Establishing Allowable Properties for

Visually-Graded Dimension Lumber from In-Grade Tests

of Full-Size Specimens

D2915 Practice for Sampling and Data-Analysis for Struc-

tural Wood and Wood-Based Products

D4442 Test Methods for Direct Moisture Content Measure-

ment of Wood and Wood-Based Materials

D7438 Practice for Field Calibration and Application of

Hand-Held Moisture Meters

E4 Practices for Force Calibration and Veriﬁcation of Test-

ing Machines

E6 Terminology Relating to Methods of Mechanical Testing

E177 Practice for Use of the Terms Precision and Bias in

ASTM Test Methods

2.2 Other Document:

NIST Voluntary Product Standard PS20 American Softwood

Lumber Standard

NOTE 1—The current version of PS20 is given as an example of a

product standard applicable to stress-graded lumber. Other product stan-

dards may apply to stress-graded lumber. For wood-based structural

materials other than stress-graded lumber, relevant product standards may

apply.

3. Terminology

3.1 Deﬁnitions—See Terminologies D9 and E6 and Prac-

tices E4 and E177 for deﬁnitions of terms used in these test

methods.

3.2 Deﬁnitions of Terms Speciﬁc to This Standard:

3.2.1 breadth, n—in a bending test, that dimension of the

specimen in the direction perpendicular to the span and

perpendicular to the direction of an applied load.

3.2.2 depth, n—in a bending test, that dimension of the

specimen in the direction perpendicular to the span and parallel

to the direction of an applied load.

3.2.3 span, n—in a bending test, the distance between the

center lines of the pivot points upon which the specimen is

supported to accommodate a transverse load.

4. Signiﬁcance and Use

4.1 These test methods provide procedures that are appli-

cable under true ﬁeld conditions, such as in a plant with

specimens not at moisture equilibrium.

4.2 The data established by these test methods can be used

as follows:

4.2.1 Develop strength and stiffness properties for the popu-

lation represented by the material being tested (that is, indi-

vidual grades, grade combinations, species, species groups, or

any other deﬁned, identiﬁable sample).

4.2.2 Conﬁrm the validity of strength and stiffness proper-

ties for the population represented by the material being tested.

4.2.3 Investigate the effect of parameters that have the

potential to inﬂuence the strength and stiffness properties of the

material, such as moisture content, temperature, knot size and

location, or slope of grain.

4.3 The procedures chosen in accordance with these test

methods shall be fully documented in the report to facilitate

correlation with test results obtained through the use of

traditional procedures, such as those set forth in Test Methods

D198.

5. Precision and Bias

5.1 The precision and bias of these test methods have not

yet been established.

6. BENDING EDGE-WISE—THIRD-POINT LOADING

6.1 Scope

6.1.1 This test method provides procedures for the determi-

nation of the strength and modulus of elasticity of stress-graded

lumber and other wood-based structural materials in bending

edge-wise, where the member depth is typically greater than or

equal to the member breadth.

NOTE 2—The use of the terms “edge-wise” and “ﬂat-wise” in these test

methods are intended to refer to the geometric limitations described

above. They are not intended to mandate that the “joist,” “edge,” “ﬂat,” or

“plank” orientation of a composite product needs to be tested using a

speciﬁc specimen geometry or protocol.

6.2 Summary of Test Methods

6.2.1 The specimen is simply supported and loaded by two

equal transverse concentrated loads equidistant from the reac-

tion points and each other. The specimen is loaded at a

prescribed rate until failure occurs or a pre-selected load or

deﬂection is reached. The load and corresponding deﬂection

are recorded when bending stiffness is to be determined. Only

the load is measured if the objective of the test is to determine

the specimen strength.

6.3 Apparatus

6.3.1 Testing Machine—A device that combines (1) a reac-

tion frame to support the specimen, (2) a loading mechanism

for applying load at a speciﬁed rate, and (3) a force-measuring

apparatus that can be calibrated to the accuracy requirements of

6.3.3.2 following the procedures outlined in Practices E4.

6.3.1.1 Load and Reaction Apparatus—The load and reac-

tion apparatus shall include bearing plates at the load and

reaction points that are at least as wide as the specimen breadth

and not exceeding the member depth in length. These bearing

plates shall have eased edges and sufficient bearing length to

avoid a localized crushing failure at the load and reaction

points. The apparatus shall also include appropriate

mechanisms, such as rollers, to minimize the development of

axial forces in the specimen. Each load and reaction point shall

include an in-plane pivot point. Bearing plates and rollers shall

be initially centered about their pivot points.

6.3.1.2 Loading Conﬁguration—The specimen shall be sim-

ply supported and loaded by two equal transverse concentrated

loads equidistant from the reaction points and each other.

NOTE 3—The apparent modulus of elasticity varies for different loading

conﬁgurations (see Practice D2915). While the loading conﬁguration that

commonly serves as the basis for design assumes a uniformly distributed

load, a conﬁguration with two concentrated loads symmetrically placed

within the span is usually more suitable for structural tests to determine

Available from National Institute of Standards and Technology (NIST), 100

Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.

D4761 − 25

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bending capacity and develop related design values. This conﬁguration

also produces a constant bending moment, free of shear, in the portion of

the specimen between the load points.

6.3.1.3 Lateral Supports—When necessary to restrict speci-

men out-of-plane displacement, lateral supports shall be used.

Specimens having a depth-to-breadth ratio of three or greater

are subject to lateral instability during loading and shall be

evaluated for adequate lateral support. Any provided lateral

supports shall restrain out-of-plane displacement, but allow

movement of the specimen in the direction of load application

with minimal frictional or other in-plane restraint.

6.3.2 Deﬂection-Measuring Apparatus—A measurement de-

vice shall be used to monitor the deﬂection of the specimen

when the bending stiffness is to be determined. Deﬂection shall

be permitted to be measured directly as the displacement of the

loading head of the testing machine or as direct measurement

of the specimen movement relative to the reaction frame at

mid-span. In the former case, deﬂection is expressed as the

average displacement of the load-bearing plates with respect to

the reaction-bearing plates. If, because of the design of the

apparatus, the deﬂection measurement includes extraneous

components, the deﬂection data shall be permitted to be

adjusted for such extraneous components. However, if the

extraneous components are an appreciable portion of the total

measurement, then the test apparatus shall be re-examined for

its suitability. In all instances, the report shall include a

complete description of test conditions, extraneous

components, and data adjustment procedures.

NOTE 4—Possible sources of extraneous components of deﬂection with

either measurement type might include: ﬂexure of the load and reaction

frame components, slack or looseness in the ﬁxture connections, crushing

of the material surface at the bearing plates, and/or geometric imperfec-

tions of the tested material. These factors typically result in an overesti-

mation of the member deﬂection and a conservative underestimation of

the measured stiffness. Provided test results with extraneous components

are repeatable over the range of materials typically tested, adjustment

factors to remove this bias may be developed based upon matched

correlations for similar tests of similar materials using Test Methods

D198. As an alternative, a mid-span yoke-mounted deﬂection device

similar to that described by Test Methods D198 may be used with these

procedures to improve accuracy and mitigate the need for adjustment.

6.3.3 Accuracy:

6.3.3.1 The two load points shall be located within 6

⁄

in.

(1.6 mm) of the position determined in accordance with 6.3.1.2

and 6.4.2.2.

6.3.3.2 The force-measuring apparatus shall be such as to

permit load measurements with an error not to exceed 61.0 %

of the load for loads greater than or equal to 1000 lbf (4450 N).

For loads smaller than 1000 lbf, the error shall not exceed

610 lbf (45 N).

6.3.3.3 The deﬂection-measuring apparatus shall be such as

to permit deﬂection measurements with an error not to exceed

61.0 % of the deﬂection with deﬂections greater than or equal

to 0.150 in. (4 mm).

NOTE 5—Bending stiffness estimates obtained from total specimen

deﬂections of 0.150 in. (4 mm) or less have a signiﬁcant measurement

error component and are not recommended.

6.3.3.4 The cross-sectional dimensions of the member shall

be measured to at least three signiﬁcant ﬁgures.

6.4 Specimen

6.4.1 Cross Section—Unless the effect of cross-section

modiﬁcations is a test evaluation objective, the specimen shall

be tested without modifying the dimensions of the commercial

cross section.

6.4.2 Length:

6.4.2.1 The minimum specimen length shall be the span,

determined in accordance with 6.4.2.2, plus an extension

beyond the center lines of the end reactions, such that the

specimen will not slip off the bearing plates at the end reactions

during the test. In cases where the unsupported specimen

length outside the span at an end reaction (overhang) exceeds

ten times the specimen depth, report the amount of overhang at

each end reaction.

6.4.2.2 The span depends on the purpose of the test pro-

gram. It is customary to express the span as a multiple of the

specimen depth. While spans that currently serve as a basis

suitable for testing range from 17 to 21 times the depth of the

specimen, other spans shall be permitted.

NOTE 6—Practice D2915 gives an indication of the impact that varying

span-to-depth ratios have upon the measured member stiffness. The depth

in this section refers to the relevant size speciﬁed in the size classiﬁcation

of the applicable product standard. As an example for stress-graded

lumber, the depth used to determine the span will typically be the dressed

dry size speciﬁed in the size classiﬁcation of the current version of PS20.

For example, 3.5 in. (89 mm) should be used to calculate the span-to-

depth ratio for members with a nominal depth of 4 in.

6.4.3 Conditioning—Specimens shall be permitted to be

tested as produced or conditioned (for example, temperature,

moisture content, or treatment), depending on the purpose of

the test program. If the temperature of the specimens at the

time of testing is less than 45 °F (7 °C) or more than 90 °F

(32 °C), that temperature shall be reported.

6.5 Procedure

6.5.1 Specimen Measurements:

6.5.1.1 Before testing, measure and record the cross-

sectional dimensions of every specimen at the center of the

span unless another location is more appropriate to the purpose

of the test.

6.5.1.2 Following the test, measure the moisture content of

the specimens at a location away from the ends and as close to

the failure zone as practical in accordance with the procedures

outlined in Test Methods D4442 or using a calibrated moisture

meter according to 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.

6.5.2 Lengthwise Positioning—The positioning of the speci-

men across the span with respect to speciﬁc specimen charac-

teristics shall be addressed by a within-piece sampling plan for

the test program. The procedure shall be documented and the

resulting specimen length shall comply with the provisions of

6.4.2. The plan shall also detail how the tension edge is

selected.

NOTE 7—Two possible approaches used for lengthwise positioning may

be to locate the specimen across the span without bias regarding defects

or to locate speciﬁc defects near the center of the span and to deliberately

or randomly position a defect at the tension or compression side of the

D4761 − 25

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标签： #标准试验 #结构 #试验方法

摘要：

本文介绍了 ASTM D4761 - 25 标准，即木材及木质结构材料力学性能的标准试验方法。该标准为评估木材、胶合木、单板层积材等木质材料在静态载荷下的抗弯强度、弹性模量、剪切性能等关键力学指标提供了统一的试验程序与条件。内容涵盖试样制备、加载速率、支承跨距及数据记录等核心要点，适用于工程木制品的质量检验、研发与合规性评估。掌握该标准有助于提升木结构设计与建造中的材料性能可靠性，并确保测试结果的可比性与可复现性。

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ASTM D4761 - 25 木材及木质结构材料力学性能的标准试验方法

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