1、Designation: D 7469 08Standard Test Methods forEnd-Joints in Structural Wood Products1This standard is issued under the fixed designation D 7469; 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.INTRODUCTIONAdhesive bonded end-joints are used in structural glued wood products. The bond performance ofthese end-joints is only one of several parameter
3、s that influence the in-service performance of theseproducts. Evaluating the performance of these end-joints require specific tests.The testing regimen, which may consist of one or more of the test methods specified in this standard,is dependent on the type of product, the stage in the manufacturing
4、 of the product or sub-componentswhen the testing is to be performed, and the objective of the evaluation. Appendix X1-Appendix X7provide an overview of considerations for developing a testing regimen.1. Scope1.1 This standard provides test methods for evaluating thestructural capacity and integrity
5、 of end-joints in structuralwood products.1.2 End-joints are manufactured by adhesive bonding ofmachined, mated surfaces at the ends of two pieces of lumberto form a joint. Typical end-joint configurations include fingerjoints and scarf joints. The combination of one or moreend-joints and the adjoin
6、ing sections of the structural woodproduct within the assembly is considered to be the testspecimen.1.3 Off-line test methods include: (1) Axial Tension, (2)Bending, and (3) Cyclic Delamination.1.4 In-line test methods include: (1) Tension Proofload and(2) Bending Proofload.1.5 The values stated in
7、inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
8、s theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD 198 Test Methods of Stat
9、ic Tests of Lumber in StructuralSizesD 1101 Test Methods for Integrity of Adhesive Joints inStructural Laminated Wood Products for Exterior UseD 1151 Practice for Effect of Moisture and Temperature onAdhesive BondsD 1183 Practices for Resistance of Adhesives to CyclicLaboratory Aging ConditionsD 255
10、9 Specification for Adhesives for Structural Lami-nated Wood Products for Use Under Exterior (Wet Use)Exposure ConditionsD 2915 Practice for Evaluating Allowable Properties forGrades of Structural LumberD 3434 Test Method for Multiple-Cycle Accelerated AgingTest (Automatic Boil Test) for Exterior We
11、t Use WoodAdhesivesD 4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base MaterialsD 4444 Test Method for Laboratory Standardization andCalibration of Hand-Held Moisture Meters1These test methods are under the jurisdiction of ASTM Committee D07 onWood and are the direct r
12、esponsibility of Subcommittee D07.01 on FundamentalTest Methods and Properties.Current edition approved Nov. 1, 2008. Published December 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vol
13、ume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 4688 Test Method for Evaluating Structural Adhesivesfor Finger Jointing LumberD 4761 Test Methods for
14、Mechanical Properties of Lumberand Wood-Base Structural MaterialD 5266 Practice for Estimating the Percentage of WoodFailure in Adhesive Bonded JointsD 7247 Test Method for Evaluating the Shear Strength ofAdhesive Bonds in Laminated Wood Products at ElevatedTemperaturesE4 Practices for Force Verific
15、ation of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods3. Terminology3.1 Terms used in these methods shall be as defined inTerminologies D9and E6and Practices E4and E 177.3.2 Definitions of Terms Spe
16、cific to This Standard:3.2.1 delaminationseparation of a bondline due to dimen-sional changes (swelling and shrinkage) of the wood aroundthe joint caused by extreme changes in the moisture content.3.2.2 finger jointa joint formed by bonding two pieces oflumber with ends machined to a mated finger-li
17、ke profile (Fig.1).3.2.3 finger joint specimenboard segments joined at oneor both ends by finger joints to form an assembly and obtainedfrom a finger joint production line for testing.3.2.4 finger lengthlength of machined finger along thelongitudinal axis of the full-size member from the finger tip
18、tothe base of the finger (Fig. 1).3.2.5 finger pitchwidest width of machined finger at thebase of the joint (Fig. 1).3.2.6 gauge lengththe clear distance between the grips fora specimen subjected to axial tensile loading.3.2.7 horizontal finger jointfinger joint where the fingerprofile appears only
19、on the narrow face of the lumber.3.2.8 in-line testa test that is carried out on all productionfrom a continuous manufacturing process.3.2.9 off-line testa test that is carried out on a sampletaken from a continuous manufacturing process or frominventory of the product.3.2.10 outer fingerthe finger
20、at the edges of the faceshowing the finger profile (Fig. 1).3.2.11 proofload testinga test where a preselected load orstress level is applied to the specimen.3.2.12 scarf jointa joint formed by bonding two pieces oflumber with ends machined with a single sloping profile. Thelength of the specimen cr
21、oss-section occupied by the scarf jointis the run of the slope (Fig. 2).3.2.13 spanthe distance between the centerlines of endreactions on which the test specimen is supported to accom-modate a transverse bending load.3.2.14 standard dry dimensionsthe cross-sectional sizeused in design for sawn lumb
22、er, this is also known as thestandard dry size.3.2.15 tip gapdistance between the finger tip and the baseof the finger in the opposing segment (Fig. 1).3.2.16 tip thicknesssmallest width of machined finger(Fig. 1).3.2.17 vertical finger jointfinger joint where the fingerprofile appears only on the w
23、ide face of the lumber.4. Significance and Use4.1 These test methods are applicable to specimens with orwithout specific conditioning regimens. Tests are permitted toFIG. 1 Finger Joint ProfileD7469082be performed on specimens that are not at moisture equilib-rium, such as under production condition
24、s in a plant, or onspecimens that have been conditioned to specified moisturecontent or durability conditioning prior to testing.4.2 These test methods can be used as follows:4.2.1 To standardize the determination of strength propertiesfor the material and joint being tested.4.2.2 To investigate the
25、 effect of parameters that mayinfluence the structural capacity of the joint, such as jointprofile, adhesive type, moisture content, temperature, andstrength-reducing characteristics in the assembly.4.3 These test methods do not intend to address all possibleexposure or performance expectations of e
26、nd-joints. The fol-lowing are some performance characteristics not considered:4.3.1 Long-term strength and permanence of the woodadhesive.4.3.2 Time dependent mechanical properties of the joint.4.3.3 Elevated temperature performance of the joint.AXIAL TENSION TEST METHOD (OFF-LINE)5. Scope5.1 This t
27、est method provides procedures for the determi-nation of the axial tensile capacity of full-size end-jointspecimen off-line.5.2 Applications of this test method include: end-jointqualification and daily quality control of production, and otherpurposes where the strength of a full-size end-joint must
28、 beverified or determined.6. Summary of Test Method6.1 The test specimen is subjected to an axial tensile load.The length of the specimen is short enough such that failuresoccur primarily at or as a result of the joint, but long enoughsuch that the stresses around the joint are not affected by thegr
29、ips.6.2 Except as specified below, the specimens shall be testedin accordance with Test Methods D 4761 for Axial Strength inTension.6.3 The specimen is loaded so that failure occurs or apreselected load is reached within the prescribed amount oftime. The elapsed test time and the maximum load shall
30、berecorded.NOTE 1It is preferred to apply load at a constant rate of increase.Either load or displacement control is acceptable. Apply load at a rate thatis as close to constant as is practical. Sudden increases in load should beavoided.7. Apparatus7.1 Test MachineAs specified in Test Methods D 4761
31、.7.2 Grips or Clamping DevicesAs specified in Test Meth-ods D 4761.NOTE 2Grip designs that do not minimize damage from clampingmay result in a high frequency of failure at the edge of the grips.Generally, if a specimen fails at the edge of the grips, the result should bedisregarded unless the load l
32、evel attains a load level that is sufficient todemonstrate a minimum end-joint capacity. When a high frequency of griprelated failure occurs at or below the load levels of interest, the gripsshould be redesigned as excessive culling of specimens for this reasonmay impact the representativeness of th
33、e tensile strength for the sampletested.7.3 Distance Between GripsThe gauge length shall beselected such that the edges of the grips are at least 2 ft (610mm) apart for finger joints, and at least 2 ft (610 mm) longerthan the length of the joint for scarf joints.NOTE 3To maximize data comparability,
34、 a gauge length of 2 ft (610mm) is typically recommended for evaluating single joints. However, tostudy, for example, the weakest joint in a sample of consecutive joints,other gauge lengths can be used. While the maximum gauge length is notlimited, a long gauge length may result in an excessive numb
35、er of failuresaway from the joint, which is not desirable for the purposes of evaluatingthe joint performance.7.4 AccuracyAs specified in Test Methods D 4761.8. Test Specimens and Conditioning8.1 Cross-SectionThe specimen shall be tested withoutmodifying the dimensions of the commercial cross-sectio
36、n.The use of reduced cross-section test specimens is permissibleaccording to considerations and guidelines for developing testprocedures provided in Appendix X5.8.2 LengthThe minimum specimen length shall be thegauge length, determined in accordance with 7.3, plus anyrequired length to achieve conta
37、ct along the full length of thegrips.8.3 ConditioningSpecimens are permitted to be tested asproduced or following a specified conditioning regimen de-pending on the purpose of the test program. The specimenconditions and details of the conditioning regimen, if appli-cable, shall be reported.9. Proce
38、dure9.1 Specimen Measurements:9.1.1 Cross-Sectional DimensionsThe cross-sectional di-mensions of each specimen for which the tensile strength is tobe determined shall be measured to the nearest 0.01 in. (0.25mm) and recorded. Where the cross-sectional dimensions differon either side of the joint, su
39、ch as when testing samples beforethey are planed to a standard size, the cross-sectional dimen-sions used to calculate the tensile strength shall be reported.The width and thickness should be measured at the leastdimensional plane of the adjoining segment.NOTE 4When testing for end-joint quality con
40、trol at a productionfacility, it may be acceptable to determine the tensile strength using thestandard dry cross-sectional dimensions.FIG. 2 Scarf Joint ProfileD74690839.1.2 Moisture ContentUnless otherwise specified by thedurability conditioning protocol, the moisture content of thespecimens tested
41、 after moisture or durability conditioning shallbe measured on each side of the joint in accordance with theprocedures outlined in Test Methods D 4442 or D 4444 andrecorded. For specimens tested as produced from a manufac-turing process in which lumber moisture content is controlledor where all spec
42、imens are conditioned to uniform moisturecontent, moisture content measurements for each specimen arenot required.9.2 Test SetupThe end-joint shall be centered between thetwo grips. The specimen shall also be centered in the grips sothat the longitudinal axis of the specimen coincides with thedirect
43、ion of the load application. Load shall be applied to thespecimen at a rate determined in accordance with 9.3.NOTE 5Centering the joint in the grip span minimizes the biasbetween joint tests due to bending moments induced by grip head balance.It is recognized that bending moments caused by non-homog
44、eneity in thespecimens mechanical properties cannot be eliminated.9.3 Speed of TestingA constant test rate shall be selectedfor testing the sample such that the specimen failure load isachieved between 1 and 10 min.9.4 Maximum LoadThe maximum load attained in the testshall be recorded.9.5 Record of
45、FailureDepending on the purpose of thetest, a description of the failure mode and percentage of woodfailure may be required.NOTE 6It is recommended that for finger joints the failure mode beclassified according to one of the failure modes described in Test MethodD 4688 and recorded. In addition, Pra
46、ctice D 5266 can be used to recordpercentage of wood failure. Irregularities or the presence of strengthreducing defects in the joint should also be recorded.NOTE 7Because target test load levels for assessing joint quality arewell above the product design capacity, failure away from the joint are n
47、otuncommon and should be noted when they occur. If failure occurs abovea predetermined load level, it may be acceptable to use the test result toimply a minimum joint strength. However, if there is a high frequency offailure occurring away from the joint and at the load levels below thatnecessary to
48、 monitor the joint quality, consideration should be given tousing another test mode. Otherwise, the remaining samples may no longerbe representative of the tensile strength for the production.BENDING TEST METHOD (OFF-LINE)10. Scope10.1 This test method provides off-line test procedures forthe determ
49、ination of the capacity of the end-joint in bending onshort spans subjected to a 4-point loading.10.2 Applications of this test method include: end-jointqualification and daily quality control, and other purposeswhere the strength of a full-size end-joint are to be verified ordetermined.11. Summary of Test Method11.1 The test specimen is simply supported and loaded bytwo equal, concentrated forces spaced equidistant from thecenter of the supports. The specimen is loaded so that failureoccurs or a preselected load is reached within the prescribedam
