1、Designation: D2719 89 (Reapproved 2007)D2719 13Standard Test Methods forStructural Panels in Shear Through-the-Thickness1This standard is issued under the fixed designation D2719; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year 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.1. Scope1.1 These test methods determine the shear through-the-thickness properties of structural panels associated with
3、shear distortionof the major axis. Structural panels in use include plywood, wafer board, oriented strand board, and composites of veneer and ofwood based layers. Three test methods are included which differ somewhat in their application:Test Method SectionA. Small Panel Shear Test 5B. Large Panel S
4、hear Test 6C. Two Rail Shear Test 7The choice of test method will be determined in part by the purpose of the tests, characteristics of test material, and equipmentavailability. In general, Test Method B or C for large specimens is preferred when equipment, amount of test material, andexperimental p
5、lan permit.1.1.1 Test Method A: Small Panel Shear TestThis test method is suitable for testing small samples of uniform materialincluding investigations of the effects of grain direction or orientation and of many raw materials and manufacturing processvariables which influence shear properties unif
6、ormly throughout the specimen. The test method is unsuited for determining effectsof grade and manufacturing features such as density variations, knots, and core gaps within the specimen.1.1.2 Test Method B: Large Panel Shear TestThis test method is regarded as giving the most accurate modulus of ri
7、gidity andis therefore recommended for elastic tests of materials to be used in stress analysis studies of test structures. This test method alsoyields excellent shear strength values for clear material. However, in spite of the large size of the specimen, failures generally occuronly in narrow zone
8、s at the perimeter of the test area. This characteristic, a result of the heavy perimeter framing, causes this testmethod to be generally unsuited for determining grade and manufacturing effects such as density variations, core gaps, and knotsthat are not uniformly distributed throughout the panel.
9、Generally, only in cases where effects of these factors under conditions ofheavy perimeter framing are desired, should the test method be applied.1.1.3 Test Method C: Two-Rail Shear Test This test method is applicable to a wide variety of materials and problems. Thespecimen fabrication and test proc
10、edures are somewhat simpler than in Test Methods A and B. The specimen is free to shearparallel to its 24-in.(610-mm) length dimension anywhere within the 8-in. (203-mm) width between rails. Thus, the test methodis well suited for determining grade and manufacturing effects such as core gaps and kno
11、ts occupying and affecting small areas.The test method is not so ideally suited for determination of modulus of rigidity, but when adjusted for strain distribution effects,values approximating those obtained by Test Method B result. The test method simulates effects of heavy framing when expectedpla
12、nes of weakness are oriented perpendicular to rails and no framing at all when parallel to rails.NOTE 1Asmaller scale version based on the principles of this two rail shear method is contained in Test Methods D1037 section 27. The results fromTest Methods D1037 section 27 may not be equivalent to th
13、e results from Test Methods D2719 Method C.1.2 Significant differences, moderate to small in magnitude, among the three test methods have been found to exist when thesetest methods are applied to plywood of clear straight-grained veneers. Therefore, when comparisons are made among test results,it is
14、 recommended that the same test method be used throughout.1.3 This standard does not purport to address all of the safety concerns, 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 applicabili
15、ty of regulatorylimitations prior to use.1 These test methods are under the jurisdiction of ASTM Committee D07 on Wood and are the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved April 1, 2007Oct. 1, 2013. Published April 2007October 2013. Originally approved
16、in 1969. Last previous edition approved in 20012007 asD2719 89 (2001).(2007). DOI: 10.1520/D2719-89R07.10.1520/D2719-13.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 m
17、ay not be technically possible to adequately depict all changes accurately, ASTM 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 Har
18、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2D1037 Test Methods for Evaluating Properties of Wood-Base Fiber and Particle Panel MaterialsD2395 Test Methods for Specific Gravity of Wood and Wood-Based MaterialsD4442 Test Methods fo
19、r Direct Moisture Content Measurement of Wood and Wood-Base Materials3. Significance and Use3.1 The strength and modulus of rigidity of structural panels in shear through-the-thickness obtained by these test methods arerequired for the rigorous design of many lumber-panel structural components such
20、as trusses with panel gussets, box beams, foldedplate roofs, and space plane structures, as well as floor and roof diaphragms, and shear walls. These properties are of secondaryimportance in typical roof deck and sheathing applications, and in crates and shipping containers.3.2 Veneer produced by sl
21、icing or rotary peeling may contain fine checks or separations parallel to the grain on the knife sideof the veneer that are produced as the knife is forced through the wood. These checks are termed “knife checks” to distinguishthem from occasional checks that may be formed on the opposite side of t
22、he veneer by forces at the compression bar, and fromchecks caused by drying. Average depth of knife checks has been found to strongly influence shear properties in plywood panelsand may be of significance in veneer incorporated in composite panels. Measurement of depth of knife checks is recommended
23、in these test methods.3.3 To control or define other variables influencing shear properties, these test methods require determination of moisturecontent and elapsed time to failure. The conditioning of test material in controlled atmosphere and determination of specific gravityare recommended.4. Con
24、trol of Moisture Content4.1 Structural panel samples to be tested at a specific temperature/relative humidity shall be conditioned to approximate constantweight in controlled atmospheric conditions before gluing wood rails. Conditioning of fabricated specimens at the sametemperature and relative hum
25、idity shall be continued until the adhesive has cured sufficiently to ensure adequate bond strength.For approximating moisture conditions of structural panels used under dry conditions, a relative humidity of 65 6 2 % at atemperature of 68 6 6F (20 6 3C) is recommended.5. Test Method ASmall Panel Sh
26、ear Test5.1 SummaryA specimen having a square shear area bounded on each side by solid wood blocks glued to both sides of thespecimen is loaded in compression along one diagonal in a conventional testing machine. Forces are applied to the glued-on blocksthrough a roller bracket assembly which causes
27、 the resultant forces to act collinearly with the edge of the shear test area. Thisloading method most nearly produces uniform pure shear. Shear strength is determined from maximum load, and modulus ofrigidity may be calculated from measurements of compression strain along the compression diagonal o
28、f the specimen.5.2 Test SpecimenDimensions shown in Fig. 1 of the panel specimen and reinforcing blocks depend upon panel thickness.Distance between blocks, L, shall not exceed 20 times specimen thickness, and block width and thickness shall not be less than5 and 2.5 times specimen thickness, respec
29、tively. Reinforcing blocks shall be of birch, maple, or other wood of similar strength2 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
30、page on the ASTM website.Metric Equivalentsin.mm1161.61212.7FIG. 1 Small Panel Shear Specimen and DimensionsD2719 132and rigidity. The average of specimen thickness at two diagonally opposite corners and the dimensions of the shear area inside thereinforcing blocks shall be determined and recorded t
31、o the nearest 0.3 % or 0.001 in. (0.025 mm), whichever is larger.5.3 LoadingApply the load by special steel loading blocks which articulate with the rollers and pins attached to the testspecimen. The angle between faces of the loading block shall be 90 and between each face and the base the angle sh
32、all be 45.Aspherical bearing block, preferably of the suspended, self-aligning type, shall be employed in the loading system.Apply the loadcontinuously throughout the test with a uniform motion of the movable head of the testing machine equal to 0.0025 in./in. of testarea diagonal length/min (0.0025
33、 mm/mm/min) corresponding to a shear strain rate of 0.005 in./in./min (0.005 mm/mm/min)within a permissible variation of 625 %.5.3.1 Load each of the eight reinforcing blocks through roller brackets clamped to the reinforcing block across its width orattached by other means and applying a compressiv
34、e force to the end of the reinforcing block through a surface contact area ofat least 0.75 in.2 (484 mm2). These bearing surfaces shall be firmly seated against the ends of their respective reinforcing blocksduring assembly. Rollers shall be centered at the inner edge of the reinforcing block and 1.
35、25 in. (31.8 mm) from the loaded endof the reinforcing block. Moderate clamping pressure holding brackets to the reinforcing blocks applied perpendicular to the planeof the panel is permitted but shall not be excessive.5.3.1.1 Fig. 2 illustrates detail of suitable roller brackets and their method of
36、 attachment to the reinforcing blocks with smallwood wedges. Fig. 3 shows a specimen loaded by means of roller brackets, and Fig. 4 gives working drawings for these brackets.Brackets are clamped across the width of the reinforcing blocks by driving small wedges between a projection on the bracket an
37、dthe reinforcing block. The clamping bolt is used to apply moderate clamping pressure perpendicular to the plane of the specimen.Other bracket devices conforming to the requirements of 5.3.1 are permitted but shall be described in detail in the report of testresults.5.3.1.2 Measure the elapsed time
38、from initiation of loading to the maximum load and record to the nearest 12 min.5.4 Measurement of DeformationWhen deformation data are desired for calculation of elastic properties, strain-measuringdevices having minimum gage length of 1 in. (25 mm) shall be attached to both sides of the specimen a
39、nd shall measurecompression strain of the vertical (or compression) diagonal, the gages being centered at its midpoint on each side. A larger gageFIG. 2 Small Panel Shear Specimen with Roller BracketsD2719 133length is preferred but shall not exceed one half the length of the diagonal. Instruments a
40、nd the accuracy of their recording shallbe to the nearest 0.0001 in. (0.0025 mm) or 2 % of expected ultimate strain, whichever is smaller. Strain readings of the two gagesshall be averaged for computation of elastic properties.5.5 Calculation:5.5.1 Calculate the maximum shear stress or shear stress
41、at the proportional limit as follows:T 50.707 P/Lt! (1)where:T = shear stress, psi (N/m2),P = load (force), lbf (N),L = length of side of shear area, in. (m), (Fig. 1), andt = thickness of shear specimen, in. (m).5.5.2 Calculate modulus of rigidity from deformation data as follows:G 50.3536 P/!L1 /L
42、t!# (2)where:G = modulus of rigidity, psi (N/m2),P/ = slope of force/deformation curve, lbf/in. (N/m),L1 = gage length, in. (m), andt = thickness of shear specimen, in. (m).6. Test Method BLarge Panel Shear Test6.1 SummaryAspecimen having a square shear area is loaded through heavy lumber rails glue
43、d to both sides of the specimenat all four edges of the shear area. Loading by a system of pins and yokes applies forces to the rails having a resultant acting atFIG. 3 Small Panel Shear Specimen with Loading and Strain-Measuring Apparatus Placed in Testing MachineD2719 134the inside edge of the she
44、ar area. Maximum shear strength is determined from maximum load and modulus of rigidity fromelongation of the tension diagonal and corresponding loads.6.2 Test SpecimensFig. 5 gives detail of the specimen as well as a suitable loading method. Shear area of the specimen shallnot be less than 24 in. (
45、610 mm) on a side, and shall not exceed 48 times total specimen thickness. When structural panels lessthan 12 in. (12.7 mm) thick or less than 148 the side of the shear area is to be tested for shear strength, two or more thicknessesof structural panels may be glued together (major axis parallel) to
46、 form a test panel of the required thickness. Specimens to betested for modulus of rigidity only may be of lesser thickness provided sufficient data can be obtained before the test is halted dueto initiation of buckling. Lumber rails having a length equal to the side of the shear area, thickness not
47、 less than 125 and width notless than 16 the length of one side of the shear area shall be glued to the structural panels with a rigid adhesive. Wider rails maybe necessary to prevent rolling shear failures between thick or high-strength panels and the rails. Corners of the structural panelsspecimen
48、 shall be notched with the inside corner of the notch provided with a fillet of 12-in. (12.7-mm) radius as shown in Fig.5. Ends of the rails to which loads are applied shall form a flat plane perpendicular to the plane of the specimen. Use of a jig toposition rails accurately at the time of assembly
49、 or a light saw cut across the end of both rails after assembly may be helpful.Depending upon the method of deformation measurement, holes for gage pins may be needed as illustrated in Fig. 5. Averagespecimen thickness shall be determined from measurements at each corner of the shear area to an accuracy of 0.001 in. (0.025 mm).Width and length of the shear area shall be measured to an accuracy of 0.01 in. (0.25 mm).6.3 LoadingLoad the specimen loading jig assembly in tension. The resultant of forces applied to a pair of rails shall be asingle fo
