1、Designation: D198 141Standard Test Methods ofStatic Tests of Lumber in Structural Sizes1This standard is issued under the fixed designation D198; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTECorrected editorially in June 2015.INTRODUCTIONNumerous evaluations of structural members of sawn lumber have been conducted in accordancewith Test Me
3、thods D198. While the importance of continued use of a satisfactory standard should notbe underestimated, the original standard (1927) was designed primarily for sawn lumber material, suchas bridge stringers and joists.With the advent of structural glued laminated (glulam) timbers, structuralcomposi
4、te lumber, prefabricated wood I-joists, and even reinforced and prestressed timbers, aprocedure adaptable to a wider variety of wood structural members was required and Test MethodsD198 has been continuously updated to reflect modern usage.The present standard provides a means to evaluate the flexur
5、e, compression, tension, and torsionstrength and stiffness of lumber and wood-based materials in structural sizes.Aflexural test to evaluatethe shear stiffness is also provided. In general, the goal of the D198 test methods is to provide areliable and repeatable means to conduct laboratory tests to
6、evaluate the mechanical performance ofwood-based materials. While many of the properties tested using these methods may also be evaluatedusing the field procedures of Test Methods D4761, the more detailed D198 test methods are intendedto establish practices that permit correlation of results from di
7、fferent sources through the use of moreuniform procedures. The D198 test methods are intended for use in scientific studies, development ofdesign values, quality assurance, or other investigations where a more accurate test method is desired.Provision is made for varying the procedure to account for
8、 special problems.1. Scope1.1 These test methods cover the evaluation of lumber andwood-based materials in structural sizes by various testingprocedures.1.2 The test methods appear in the following order:SectionsFlexure 411Compression (Short Column) 1320Compression (Long Member) 2128Tension 2936Tors
9、ion 3744Shear Modulus 45521.3 Notations and symbols relating to the various testingprocedures are given in Appendix X1.1.4 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information on
10、lyand are not considered standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limita
11、tions prior to use.2. Referenced Documents2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD1165 Nomenclature of Commercial Hardwoods and Soft-woodsD2395 Test Methods for Density and Specific Gravity (Rela-tive Density) of Wood and Wood-Based MaterialsD2915 Practice for Sa
12、mpling and Data-Analysis for Struc-tural Wood and Wood-Based Products1These test methods are under the jurisdiction of ASTM Committee D07 onWood and are the direct responsibility of Subcommittee D07.01 on FundamentalTest Methods and Properties.Current edition approved Feb. 1, 2014. Published May 201
13、4. Originallyapproved in 1924. Last previous edition approved in 2013 as D19813. DOI:10.1520/D0198-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards
14、Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3737 Practice for Establishing Allowable Properties forStructural Glued Laminated Timber (Glulam)D4442 Test Methods for Direct Moisture Content
15、Measure-ment of Wood and Wood-Base MaterialsD4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural MaterialD7438 Practice for Field Calibration and Application ofHand-Held Moisture MetersE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods
16、 of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE2309 Practices for Verification of
17、Displacement MeasuringSystems and Devices Used in Material Testing Machines3. Terminology3.1 DefinitionsSee Terminology E6, Terminology D9, andNomenclature D1165.3.2 Definitions:Definitions of Terms Specific to This Stan-dard:3.2.1 composite wood beama laminar construction com-prising a combination
18、of wood and other simple or complexmaterials assembled and intimately fixed in relation to eachother so as to use the properties of each to attain specificstructural advantage for the whole assembly.3.2.2 depth of beam (d)that dimension of the beam that isperpendicular to the span and parallel to th
19、e direction in whichthe load is applied (Fig. 1).3.2.3 shear spantwo times the distance between a reactionand the nearest load point for a symmetrically loaded beam(Fig. 1).3.2.4 shear span-depth ratiothe numerical ratio of shearspan divided by beam depth.3.2.5 span ()the total distance between reac
20、tions onwhich a beam is supported to accommodate a transverse load(Fig. 1).3.2.6 span-depth ratio (/d)the numerical ratio of totalspan divided by beam depth.3.2.7 structural beamsawn lumber, glulam, structuralcomposite lumber, prefabricated wood I-joists, or other similarmaterial for which strength
21、or stiffness, or both, are primarycriteria for the intended application and which usually are usedin full length and in cross-sectional sizes greater than nominal2 by 2 in. (38 by 38 mm).FLEXURE4. Scope4.1 This test method covers the determination of the flexuralproperties of structural beams. This
22、test method is intendedprimarily for beams of rectangular cross section but is alsoapplicable to beams of round and irregular shapes, such asround posts, pre-fabricated wood I-joists, or other specialsections.5. Summary of Test Method5.1 The structural member, usually a straight or a slightlycambere
23、d beam of rectangular cross section, is subjected to abending moment by supporting it near its ends, at locationscalled reactions, and applying transverse loads symmetricallyimposed between these reactions. The beam is deflected at aprescribed rate, and coordinated observations of loads anddeflectio
24、ns are made until rupture occurs.6. Significance and Use6.1 The flexural properties established by this test methodprovide:6.1.1 Data for use in development of grading rules andspecifications;6.1.2 Data for use in development of design values forstructural members;6.1.3 Data on the influence of impe
25、rfections on mechanicalproperties of structural members;6.1.4 Data on strength properties of different species orgrades in various structural sizes;6.1.5 Data for use in checking existing equations or hypoth-eses relating to the structural behavior of beams;FIG. 1 Flexure Test MethodExample of Two-P
26、oint LoadingD198 14126.1.6 Data on the effects of chemical or environmentalconditions on mechanical properties;6.1.7 Data on effects of fabrication variables such as depth,taper, notches, or type of end joint in laminations; and6.1.8 Data on relationships between mechanical and physi-cal properties.
27、6.2 Procedures are described here in sufficient detail topermit duplication in different laboratories so that comparisonsof results from different sources will be valid. Where specialcircumstances require deviation from some details of theseprocedures, these deviations shall be carefully described i
28、n thereport (see Section 11).7. Apparatus7.1 Testing MachineA device that provides (1) a rigidframe to support the specimen yet permit its deflection withoutrestraint, (2) a loading head through which the force is appliedwithout high-stress concentrations in the beam, and (3)aforce-measuring device
29、that is calibrated to ensure accuracy inaccordance with Practices E4.7.2 Support ApparatusDevices that provide support of thespecimen at the specified span.7.2.1 Reaction Bearing PlatesThe beam shall be sup-ported by metal bearing plates to prevent damage to the beamat the point of contact between b
30、eam and reaction support (Fig.1). The plates shall be of sufficient length, thickness, and widthto provide a firm bearing surface and ensure a uniform bearingstress across the width of the beam.7.2.2 Reaction SupportsThe bearing plates shall be sup-ported by devices that provide unrestricted longitu
31、dinal defor-mation and rotation of the beam at the reactions due to loading.Provisions shall be made to restrict horizontal translation of thebeam (see 7.3.1 and Appendix X5).7.2.3 Reaction Bearing AlignmentProvisions shall bemade at the reaction supports to allow for initial twist in thelength of t
32、he beam. If the bearing surfaces of the beam at itsreactions are not parallel, the beam shall be shimmed or theindividual bearing plates shall be rotated about an axis parallelto the span to provide full bearing across the width of thespecimen. Supports with lateral self-alignment are normallyused (
33、Fig. 2).7.2.4 Lateral SupportSpecimens that have a depth-to-width ratio (d/b) of three or greater are subject to out-of-planelateral instability during loading and require lateral support.Support shall be provided at least at points located abouthalfway between a reaction and a load point. Additiona
34、lsupports shall be permitted as required to prevent lateral-torsional buckling. Each support shall allow vertical movementwithout frictional restraint but shall restrict lateral displace-ment (Fig. 3).7.3 Load ApparatusDevices that transfer load from thetesting machine at designated points on the sp
35、ecimen. Provi-sions shall be made to prevent eccentric loading of the loadmeasuring device (see Appendix X5).7.3.1 Load Bearing BlocksThe load shall be appliedthrough bearing blocks (Fig. 1), which are of sufficient thick-ness and extending entirely across the beam width to eliminatehigh-stress conc
36、entrations at places of contact between beamand bearing blocks. Load shall be applied to the blocks in sucha manner that the blocks shall be permitted to rotate about anaxis perpendicular to the span (Fig. 4). To prevent beamdeflection without restraint in case of two-point loading, metalbearing pla
37、tes and rollers shall be used in conjunction with oneor both load-bearing blocks, depending on the reaction supportconditions (see Appendix X5). Provisions such as rotatablebearings or shims shall be made to ensure full contact betweenthe beam and the loading blocks. The size and shape of theseloadi
38、ng blocks, plates, and rollers may vary with the size andshape of the beam, as well as for the reaction bearing plates andsupports. For rectangular beams, the loading surface of theblocks shall have a radius of curvature equal to two to fourtimes the beam depth. Beams having circular or irregularcro
39、ss-sections shall have bearing blocks that distribute the loaduniformly to the bearing surface and permit unrestraineddeflections.7.3.2 Load PointsLocation of load points relative to thereactions depends on the purpose of testing and shall berecorded (see Appendix X5).7.3.2.1 Two-Point LoadingThe to
40、tal load on the beamshall be applied equally at two points equidistant from thereactions. The two load points will normally be at a distancefrom their reaction equal to one third of the span (/3)(third-point loading), but other distances shall be permitted forspecial purposes.7.3.2.2 Center-Point Lo
41、adingA single load shall be ap-plied at mid-span.7.3.2.3 For evaluation of shear properties, center-point load-ing or two-point loading shall be used (see Appendix X5).7.4 Deflection-Measuring Apparatus:FIG. 2 Example of Bearing Plate (A), Rollers (B), and Reaction-Alignment-Rocker (C), for Small Be
42、amsD198 14137.4.1 GeneralFor modulus of elasticity calculations, de-vices shall be provided by which the deflection of the neutralaxis of the beam at the center of the span is measured withrespect to a straight line joining two reference points equidis-tant from the reactions and on the neutral axis
43、 of the beam.7.4.1.1 The apparent modulus of elasticity (Eapp) shall becalculated using the full-span deflection (). The referencepoints for the full-span deflection measurements shall bepositioned such that a line perpendicular to the neutral axis atthe location of the reference point, passes throu
44、gh the supportscenter of rotation.7.4.1.2 The true or shear-free modulus of elasticity (Esf)shall be calculated using the shear-free deflection. The refer-ence points for the shear-free deflection measurements shall bepositioned at cross-sections free of shear and stress concentra-tions (see Appendi
45、x X5).NOTE 1The apparent modulus of elasticity (Eapp) may be converted tothe shear-free modulus of elasticity (Esf) by calculation, assuming that theshear modulus (G) is known. See Appendix X2.7.4.2 Wire DeflectometerA wire stretched taut betweentwo nails, smooth dowels, or other rounded fixtures at
46、tached tothe neutral axis of the beam directly above the reactions andextending across a scale attached at the neutral axis of the beamat mid-span shall be permitted to read deflections with atelescope or reading glass to magnify the area where the wirecrosses the scale. When a reading glass is used
47、, a reflectivesurface placed adjacent to the scale will help to avoid parallax.7.4.3 Yoke DeflectometerA satisfactory device commonlyused to measure deflection of the center of the beam withrespect to any point along the neutral axis consists of alightweight U-shaped yoke suspended between nails, sm
48、oothdowels, or other rounded fixtures attached to the beam at itsneutral axis. An electronic displacement gauge, dialmicrometer, or other suitable measurement device attached tothe center of the yoke shall be used to measure verticaldisplacement at mid-span relative to the beam neutral axis (Fig.4).
49、7.4.4 Alternative DeflectometersDeflectometers that donot conform to the general requirements of 7.4.1 shall bepermitted provided the mean deflection measurements are notsignificantly different from those devices conforming to 7.4.1.The equivalency of such devices to deflectometers, such asthose described in 7.4.2 or 7.4.3, shall be documented anddemonstrated by comparison testing.NOTE 2Where possible, equivalency testing should be undertaken inthe same type of product and stiffness range for which the device will beused. Issues that should
