1、Designation: D4761 11D4761 13Standard Test Methods forMechanical Properties of Lumber and Wood-Base StructuralMaterial1This standard is issued under the fixed designation D4761; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONNumerous evaluations of the mechanical properties of wood-based structural material have beensatisfactorily con
3、ducted since the late 1920s, using Test Methods D198. Those methods are best suitedto 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 prestressedtimbers.The procedures pres
4、ented in these test methods have been derived from those set forth in TestMethods D198. They are intended primarily for application to stress-graded lumber, but can be usedfor other wood-base structural material as well. The procedures are more flexible than those in TestMethods D198, making testing
5、 in a nonlaboratory environment more feasible. Thus the test methodscan be used on production sites for field testing and quality control, as well as in laboratories forresearch applications. Key differences from Test Methods D198 are the testing speed, the deflection-measuring procedures for test s
6、pecimens under load, and the detail of data reporting. Furthermore, thetest methods do not require that specimens be loaded to failure.Since these test methods allow latitude in testing procedures, the procedures used shall be fullydocumented in the test report. It may also be desirable to correlate
7、 the results from tests carried outaccording to these test methods with test results obtained through the use of a traditional procedure,such as that set forth in Test Methods D198.1. Scope1.1 These test methods cover the determination of the mechanical properties of stress-graded lumber and other w
8、ood-basestructural material.1.2 These test methods appear in the following order:SectionBending edge-wise 6Bending flat-wise:Center point loading 7Third point loading 8Axial strength in tension 9Axial strength in compression 101.3 This standard does not purport to address all of the safety concerns,
9、 if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based
10、Products1 These test methods are under the jurisdiction ofASTM Committee D07 on Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental Test Methodsand Properties.Current edition approved July 15, 2011April 1, 2013. Published September 2011May 2013. Originally approved in 1988.
11、Last previous edition approved in 20052011 asD4761 05.D4761 11. DOI: 10.1520/D4761-11.10.1520/D4761-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards
12、Document Summary page on the ASTM website.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. Becauseit may not be technically possible to adequately depict all changes accurately, AS
13、TM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D198 T
14、est Methods of Static Tests of Lumber in Structural SizesD2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based ProductsD4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base MaterialsD7438 Practice for Field Calibration and Application of Hand-Hel
15、d Moisture MetersE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods2.2 Other Document:3NIST Voluntary Product Standard PS20 American Softwood Lumber StandardNOTE 1Th
16、e current version of PS20 is given as an example of a product standard applicable to stress-graded lumber. Other product standards mayapply to stress-graded lumber. For wood-base structural materials other than stress-graded lumber, relevant product standards may apply.3. Terminology3.1 DefinitionsS
17、ee Terminologies D9 and E6 and Practices E4 and E177 for definitions of terms used in these test methods.3.2 Definitions of Terms Specific to This Standard:3.2.1 breadththat dimension of the test specimen in the direction perpendicular to the span and perpendicular to the directionof an applied bend
18、ing load.3.2.2 depththat dimension of the test specimen in the direction perpendicular to the span and parallel to the direction of anapplied bending load.3.2.3 spanthe distance between the center lines of the pivot points upon which the test specimen is supported to accommodatea transverse bending
19、load or, for tension loading, the distance between the grips.4. Significance and Use4.1 These test methods provide procedures that are applicable under true field conditions, such as in a plant with specimens notat moisture equilibrium.4.2 The data established by these test methods can be used as fo
20、llows:4.2.1 Develop strength and stiffness properties for the population represented by the material being tested (that is, individualgrades, grade combinations, species, species groups, or any other defined, identifiable sample).4.2.2 Confirm the validity of strength and stiffness properties for th
21、e population represented by the material being tested.4.2.3 Investigate the effect of parameters that may influence the strength and stiffness properties of the material, such asmoisture content, temperature, knot size and location, or slope of grain.4.3 The procedures chosen in accordance with thes
22、e test methods shall be fully documented in the report to facilitate correlationwith test results obtained through the use of traditional procedures, such as those set forth in Test Methods D198.5. Precision and Bias5.1 The precision and bias of these test methods have not yet been established.6. BE
23、NDING EDGE-WISE6.1 Scope6.1.1 This test method provides procedures for the determination of the strength and modulus of elasticity of stress-gradedlumber and other wood-base structural material in bending edge-wise.6.2 Summary of Test Methods6.2.1 The test specimen is simply supported and loaded by
24、two concentrated forces spaced equidistant from the supports. Thespecimen is loaded at a prescribed rate and, as applicable, observation of load or deflection, or both, is made until failure occursor a preselected load is reached.6.3 Apparatus6.3.1 Testing MachineA device that combines (1) a reactio
25、n frame to support the test specimen, (2) a loading mechanism forapplying load at a specified rate, and (3) a force-measuring apparatus that can be calibrated to the accuracy requirements of 6.3.3.2following the procedures outlined in Practices E4.6.3.1.1 Load and Support Apparatus , including beari
26、ng plates at least as wide as the specimen is broad and not exceeding themember depth in length. The bearing plates shall have eased edges and sufficient bearing lengths to avoid a localized crushingfailure at the load and support points. The apparatus shall also include appropriate mechanisms, such
27、 as rollers or pivots, to3 Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.D4761 132minimize the development of axial forces in the test specimen. Each bearing point shall include an in-plane pivot point. Bearingplates and
28、rollers shall be initially centered about their pivot points.6.3.1.2 Loading ConfigurationThe simply supported test specimen shall be subjected to two equal transverse concentratedloads spaced equidistant from the supports.NOTE 2The apparent modulus of elasticity varies for different loading configu
29、rations (see Practice D2915). While the loading configuration thatcommonly serves as the basis for assigning design values assumes a uniformly distributed load, a configuration with two concentrated loads symmetricallyplaced within the test span usually is more suitable for structural tests. This co
30、nfiguration also produces a constant bending moment, free of shear, in theportion of the specimen between the load points.6.3.1.3 Lateral Supports, when necessary, to restrict the specimen lateral deflection. Specimens having a depth-to-breadth ratioof three or greater are subject to lateral instabi
31、lity during loading and may require lateral supports. These supports shall allowmovement of the specimen in the direction of load application and have minimal frictional restraint.6.3.2 Deflection-Measuring Apparatus, for modulus of elasticity calculations, to monitor the deflection of the test spec
32、imen.Deflection may be measured directly as the displacement of the loading head of the testing machine. In this case, deflection isexpressed as the average deflection of the load points with respect to the end reaction plates. If, because of the design of theapparatus, the deflection measurement in
33、cludes extraneous components, the deflection data may be adjusted for such extraneouscomponents (Note 3). In all instances, the report shall include a complete description of test conditions, extraneous components,and data adjustment procedures.NOTE 3If the extraneous components are an appreciable p
34、ortion of the total measurement, the test apparatus should be reexamined for its suitability.6.3.3 Accuracy:6.3.3.1 The two load points shall be located within 18 in. (3 mm) of the distance determined in accordance with 6.3.1.2 and6.4.2.2.6.3.3.2 The force-measuring apparatus shall be such as to per
35、mit load measurements with an error not to exceed 61.0 % of theload for loads greater than or equal to 1000 lbf (4450 N). For loads smaller than 1000 lbf, the error shall not exceed 610 lbf (45N).6.3.3.3 The deflection-measuring apparatus shall be such as to permit deflection measurements with an er
36、ror not to exceed62.0 % of the deflection for deflections greater than or equal to 0.150 in. (4 mm). For deflections smaller than 0.150 in., the errorshall not exceed 60.003 in. (0.08 mm).6.4 Test Specimen6.4.1 Cross SectionUnless the effect of cross-section modifications is a test evaluation object
37、ive, test the specimen withoutmodifying 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 thecenter lines of the end reactions to accommodate the bearing plates, such that
38、 the specimen will not slip off the end reactions duringthe test. In cases where the unsupported specimen length outside the test span at an end reaction (overhang) exceeds 10 times thespecimen depth, report the amount of overhang at each end reaction.6.4.2.2 The span will depend on the purpose of t
39、he test program. It is customary to express the span as a multiple of the testspecimen depth (Note 4). While spans that currently serve as a basis suitable for testing range from 17 times the depth of thespecimen to 21 times the depth, other spans may be used under this test method. Practice D2915 g
40、ives an indication of the variationof the apparent modulus of elasticity with span-to-depth ratios.NOTE 4The depth here refers to the relevant size specified in the size classification of the applicable product standard (for stress-graded lumber, forexample, the depth here may refer to the dressed d
41、ry size specified in the size classification of the current version of PS20 for the nominal size, forexample, 3.5 in. (89 mm) for a nominal 4 in.).6.4.3 ConditioningSpecimens may be tested as produced or conditioned (for example, temperature, moisture content, ortreatment), depending on the purpose
42、of the test program. If the temperature of the specimens at the time of testing is less than45F (7C) or more than 90F (32C), report that temperature.6.5 Procedure6.5.1 Specimen Measurements:6.5.1.1 Before testing, measure and record the cross-sectional dimensions of every specimen to the nearest 0.0
43、40.01 in. (1 mm).(0.2 mm). The dimensions shall be reported to three significant figures. Make measurements at midlength of the specimen unlessanother location is more appropriate to the purpose of the test.6.5.1.2 Following the test, measure the moisture content of every specimen in the vicinity of
44、 the failure zone the specimens ata location away from the ends of the specimen and as close to the failure zone as practical in accordance with the proceduresoutlined in Test Methods D4442 or or using a calibrated moisture meter according to Practice D7438. The number of moisturecontent samples sha
45、ll be determined using Practice D7438. guidelines, with consideration of the expected moisture contentvariability, and any related requirements in the referenced product standards.6.5.2 Test Setup:D4761 1336.5.2.1 Lengthwise PositioningIf the specimen is to be located within the test span without bi
46、as regarding defects, achieve thisby centering the specimen in the span or by any other scheme suitable to the purpose of the test program.6.5.2.2 Selection of the Tension EdgeRandomly select the edge to be subjected to tension testing.6.5.3 Speed of TestingThe test rate shall be such that the sampl
47、e target failure load would be achieved in approximately 1 min(Note 5). The failure load should not be reached in less than 10 s nor more than 10 min (Note 6).NOTE 5Some caution is warranted here. A test rate to achieve the average failure load for the sample in approximately 1 min will differ from
48、thatto achieve a lower percentile load for the same sample in approximately 1 min.NOTE 6For stress-graded lumber, a rate of motion of the testing machine loading head of approximately 3 in. (75 mm)/min will usually permit thetest to be completed in the prescribed time for span to depth ratios of 17:
49、1 and in cases where the target failure load is the average failure load for thesample.6.5.4 Load-Deflection DataObtain load-deflection data, as required, using the apparatus specified in 6.3.2.NOTE 7For stress-graded lumber, data obtained for loads corresponding to maximum stresses in the specimen ranging from 400 to 1000 psi (2.75to 7 MPa) will usually be adequate for modulus of elasticity calculations.6.5.5 Maximum LoadIf the purpose of the test is to determine strength properties, record the maximum load attained in thetest.NOTE 8In proof loading,
