1、Designation: D198 13D198 14Standard 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 nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONNumerous evaluations of structural members of solid sawn lumber have been conducted inaccordance with Test Methods D198 27.D198. While th
3、e importance of continued use of asatisfactory standard should not be underestimated, the original standard (1927) was designedprimarily for sawn lumber material, such as solid wood bridge stringers and joists. With the advent ofstructural glued laminated (glulam) timbers, wood-plywood composite mem
4、bers, structural compositelumber, prefabricated wood I-joists, and even reinforced and prestressed timbers, a procedureadaptable to a wider variety of wood structural members is required.was required and Test MethodsD198 has been continuously updated to reflect modern usage.The present standard expa
5、nds the original standard to permit its application provides a means toevaluate the flexure, compression, tension, and torsion strength and stiffness of lumber andwood-based materials in structural sizes.Aflexural test to evaluate the shear stiffness is also provided.In general, the goal of the D198
6、to wood members of all types. It provides methods of evaluation underloadings other than flexure in recognition of the increasing need for improved knowledge of propertiesunder such loadings as tension to reflect the increasing use of dimensions lumber test methods is toprovide a reliable and repeat
7、able means to conduct laboratory tests to evaluate the mechanicalperformance of wood-based materials. While many of the properties tested using these methods mayalso be evaluated using the field procedures of Test Methods D4761in the lower chords of, the moredetailed D198 trusses. The standard estab
8、lishes test methods are intended to establish practices thatwill permit correlation of results from different sources through the use of more uniform procedures.The D198a uniform procedure. test methods are intended for use in scientific studies, development ofdesign values, quality assurance, or ot
9、her investigations where a more accurate test method is desired.Provision is made for varying the procedure to take account offor special problems.1. Scope1.1 These test methods cover the evaluation of lumber and wood-based materials in structural sizesizes by various testingprocedures.1.2 The test
10、methods appear in the following order:SectionsFlexure 4 11Compression (Short Column) 13 20Compression (Long Member) 21 28Tension 29 36Torsion 37 44Shear Modulus 45 521.3 Notations and symbols relating to the various testing procedures are given in Appendix X1.1.4 The values stated in inch-pound unit
11、s are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1 These test methods are under the jurisdiction ofASTM Committee D07 on Wood and are the direct responsibility of Subcommit
12、tee D07.01 on Fundamental Test Methodsand Properties.Current edition approved Oct. 1, 2013Feb. 1, 2014. Published October 2013May 2014. Originally approved in 1924. Last previous edition approved in 20092013 asD198 09.D19813. DOI: 10.1520/D0198-13.10.1520/D0198-14.This document is not an ASTM standa
13、rd 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, ASTM recommends that users consult prior editions as appropriate. In all cases
14、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 States11.5 This standard does not purport to address all of the safety concerns, if any, a
15、ssociated 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 ProductsD1
16、165 Nomenclature of Commercial Hardwoods and SoftwoodsD2395 Test Methods for Specific Gravity of Wood and Wood-Based MaterialsD2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based ProductsD3737 Practice for Establishing Allowable Properties for Structural Glued Laminated T
17、imber (Glulam)D4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base MaterialsD4761 Test Methods for Mechanical Properties of Lumber and Wood-Base Structural MaterialD7438 Practice for Field Calibration and Application of Hand-Held Moisture MetersE4 Practices for Force Veri
18、fication of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Extensometer SystemsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the
19、 Precision of a Test MethodE2309 Practices for Verification of Displacement Measuring Systems and Devices Used in Material Testing Machines3. Terminology3.1 DefinitionsSee Terminology E6, Terminology D9, and Nomenclature D1165.3.2 Definitions:3.1.1 See Terminology E6, Terminology D9, and Nomenclatur
20、e D1165. A few related terms not covered in these standards areas follows:Definitions of Terms Specific to This Standard:3.2.1 composite wood beama laminar construction comprising a combination of wood and other simple or complex materialsassembled and intimately fixed in relation to each other so a
21、s to use the properties of each to attain specific structural advantagefor the whole assembly.3.2.2 depth of beambeam (d)that dimension of the beam that is perpendicular to the span and parallel to the direction inwhich the load is applied (Fig. 1).3.2.3 shear spantwo times the distance between a re
22、action and the nearest load point for a symmetrically loaded beam (Fig.1).3.2.4 shear span-depth ratiothe numerical ratio of shear span divided by beam depth.3.2.5 spanspan ()the total distance between reactions on which a beam is supported to accommodate a transverse load (Fig.1).3.2.6 span-depth r
23、atioratio (/d)the numerical ratio of total span divided by beam depth.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 Document Summary page on the ASTM
24、 website.FIG. 1 Flexure Test MethodExample of Two-Point LoadingD198 1423.2.7 structural wood beamsolid wood, laminated wood, or composite structural memberssawn lumber, glulam, structuralcomposite lumber, prefabricated wood I-joists, or other similar material for which strength or stiffness, or both
25、, are primary criteriafor 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).FLEXURE4. Scope4.1 This test method covers the determination of the flexural properties of structural beams made of solid or laminate
26、d wood,or of composite constructions. beams. This test method is intended primarily for beams of rectangular cross section but is alsoapplicable to beams of round and irregular shapes, such as round posts, I-beams, pre-fabricated wood I-joists, or other specialsections.5. Summary of Test Method5.1 T
27、he structural member, usually a straight or a slightly cambered beam of rectangular cross section, is subjected to a bendingmoment by supporting it near its ends, at locations called reactions, and applying transverse loads symmetrically imposed betweenthese reactions. The beam is deflected at a pre
28、scribed rate, and coordinatecoordinated observations of loads and deflections aremade until rupture occurs.6. Significance and Use6.1 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 developmen
29、t of working stressesdesign 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 hypo
30、theses relating to the structural behavior of beams;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; and6.1.8 Data on relationships between mec
31、hanical and physical properties.6.2 Procedures are described here in sufficient detail to permit duplication in different laboratories so that comparisons of resultsfrom different sources will be valid. Special Where special circumstances may require deviation from some details of theseprocedures. A
32、ny variationsprocedures, these deviations shall be carefully described in the report (see Section 11).7. Apparatus7.1 Testing MachineAdevice 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 witho
33、ut high-stress concentrations in the beam, and (3) a force-measuringdevice that is calibrated to ensure accuracy in accordance with Practices E4.7.2 Support ApparatusDevices that provide support of the specimen at the specified span.7.2.1 Reaction Bearing PlatesThe beam shall be supported by metal b
34、earing plates to prevent damage to the beam at the pointof contact between beam and reaction support (Fig. 1). The plates shall be of sufficient length, thickness, and width to provide afirm bearing surface and ensure a uniform bearing stress across the width of the beam.7.2.2 Reaction SupportsThe b
35、earing plates shall be supported by devices that provide unrestricted longitudinal deformationand rotation of the beam at the reactions due to loading. Provisions shall be made to restrict horizontal translation of the beam (see7.3.1 and Appendix X5).7.2.3 Reaction Bearing Alignment AlignmentProvisi
36、ons shall be made at the reaction supports to allow for initial twist inthe length of the beam. If the bearing surfaces of the beam at its reactions are not parallel, the beam shall be shimmed or theindividual bearing plates shall be rotated about an axis parallel to the span to provide full bearing
37、 across the width of the specimen.Supports with lateral self-alignment are normally used (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-plane lateralinstability during loading, thus requiringloading and require lateral support
38、. Support shall be provided at least at points locatedabout halfway between a reaction and a load point. Additional supports mayshall be used as required. permitted as required toprevent lateral-torsional buckling. Each support shall allow vertical movement without frictional restraint but shall res
39、trict lateraldisplacement (Fig. 3).7.3 Load ApparatusDevices that transfer load from the testing machine at designated points on the specimen. Provisions shallbe made to prevent eccentric loading of the load measuring device (see Appendix X5).7.3.1 Load Bearing BlocksThe load shall be applied throug
40、h bearing blocks (Fig. 1), which are of sufficient thickness andextending entirely across the beam width to eliminate high-stress concentrations at places of contact between beam and bearingD198 143blocks. Load shall be applied to the blocks in such a manner that the blocks may shall be permitted to
41、 rotate about an axisperpendicular to the span (Fig. 4). To prevent beam deflection without restraint in case of two-point loading, metal bearing platesand rollers shall be used in conjunction with one or both load-bearing blocks, depending on the reaction support conditions (seeAppendix X5). Provis
42、ions such as rotatable bearings or shims shall be made to ensure full contact between the beam and theloading blocks. The size and shape of these loading blocks, plates, and rollers may vary with the size and shape of the beam, aswell as for the reaction bearing plates and supports. For rectangular
43、beams, the loading surface of the blocks shall have a radiusof curvature equal to two to four times the beam depth. Beams having circular or irregular cross-sections shall have bearing blocksthat distribute the load uniformly to the bearing surface and permit unrestrained deflections.7.3.2 Load Poin
44、tsLocation of load points relative to the reactions depends on the purpose of testing and shall be recorded (seeAppendix X5).7.3.2.1 Two-Point LoadingThe total load on the beam shall be applied equally at two points equidistant from the reactions.The two load points will normally be at a distance fr
45、om their reaction equal to one third of the span (/3) (third-point loading),but for special purposes other distances may be specified. shall be permitted for special purposes.7.3.2.2 Center-Point LoadingIf required, a A single load canshall be applied at mid-span.7.3.2.3 For evaluation of shear prop
46、erties, center-point loading or two-point loading shall be used (see Appendix X5).7.4 Deflection-Measuring Apparatus:7.4.1 GeneralFor modulus of elasticity calculations, devices shall be provided by which the deflection of the neutral axis ofthe beam at the center of the span is measured with respec
47、t to a straight line joining two reference points equidistant from thereactions and on the neutral axis of the beam.7.4.1.1 The apparent modulus of elasticity (Eapp) shall be calculated using the full-span deflection. deflection (). The referencepoints for the full-span deflection measurements shall
48、 be positioned such that a line perpendicular to the neutral axis at the locationof the reference point, passes through the supports center of rotation.7.4.1.2 The true or shear-free modulus of elasticity (Esf) shall be calculated using the shear-free deflection. The reference pointsfor the shear-fr
49、ee deflection measurements shall be positioned at cross-sections free of shear and stress concentrations (seeAppendix X5).NOTE 1The apparent modulus of elasticity (Eappmay be corrected for shear-corrected MOE calculations, ) may be converted to the shear-free modulusof elasticity (Esf) by calculation, assuming that the shear modulus (G) is known. See Appendix X5X2.7.4.2 Wire DeflectometerDeflection may be read directly by means of a A wire stretched taut between two nails, smoothdowels, or other rounded fixtures attached to into the
