1、Designation:D271800(Reapproved 2011)Standard Test Methods forStructural Panels in Planar Shear(Rolling Shear)1This standard is issued under the fixed designation D2718;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、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 properties ofstructural panels associated with shear distortion of the planesparallel to
3、the edge planes of the panels.Both shear strengthand modulus of rigidity may be determined.Primarily,the testsmeasure the planar shear(rolling shear)strength developed inthe plane of the panel.1.2 Structural panels in use include plywood,waferboard,oriented strand board,and composites of veneer and
4、ofwood-based layers.1.3 Two test methods are included:1.3.1 Test Method APlanar shear loaded by plates.1.3.2 Test Method BPlanar shear induced by five-pointbending.1.3.3 The choice of method will be dictated by the purposeof the test and equipment available.1.3.4 Test Method A,Planar Shear Loaded by
5、 PlatesThistest method uses a rectangular panel section adhered betweensteel plates with protruding knife edges to create load at thepanel faces.This test method has been used to develop shearproperties of plywood and oriented strand board for thepurpose of confirming design values.This test method
6、does notproduce pure shear,but the specimen length is prescribed sothat the secondary stresses have a minimum effect.The methoddetermines shear strength and modulus of rigidity.1.3.5 Test Method B,Planar Shear Induced by Five-PointBendingPlanar shear stress is induced on the panel whileloaded in ben
7、ding using two continuous spans.This testmethod determines planar shear strength consistent with panelapplications under transverse loading.This test method is ableto determine shear strength at any moisture condition.1.4 This standard does not purport to address all of thesafety concerns,if any,ass
8、ociated 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 limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2395 Test Methods for Density and Specific Gravity(Rela-t
9、ive Density)of Wood and Wood-Based MaterialsD4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Based Materials3.Significance and Use3.1 Planar shear(rolling shear)characteristics of structuralpanels determined by these test methods are essential for therigorous design of va
10、rious glued wood-panel structuralcomponents,such as box beams,folded plate roofs,andstressed skin panels.Planar shear also may govern the designat low span-depth ratios encountered in floors subjected to highconcentrated loads,concrete forms at high pouring pressures,and bulk storage structures.3.2
11、The modulus of rigidity determined from Test MethodAis a composite of the entire specimen acting as a unit.Forplywood panels for which the ratio between the shear moduliof the plies with grain oriented parallel and perpendicular to theshear forces is known,the rolling shear modulus of theperpendicul
12、ar plies can be calculated.3.3 Veneer produced by slicing or rotary peeling maycontain fine checks or separations parallel to the grain on theknife side of the veneer that are produced as the knife is forcedthrough the wood.These checks are termed“knife checks”todistinguish them from occasional chec
13、ks that may be formedon the opposite side of the veneer by forces at the compressionbar,and from checks caused by drying.Knife checks can havea significant effect on rolling shear properties in plywoodpanels and may be of significance in other veneer containingpanels.Test MethodArequires(when applic
14、able)the testing ofmatching specimens having knife checks oriented both openand closed wherever possible(see Fig.1).3.4 To control or define other variables influencing rollingshear,these test methods require determination of moisture1This test method is under the jurisdiction of ASTM Committee D07
15、on Woodand is the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved Nov.1,2011.Published November 2011.Originallyapproved in 1969.Last previous edition approved in 2000 as D2718 00(2006).DOI:10.1520/D2718-00R11.2For referenced ASTM standards,visit the ASTM websi
16、te,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 content,specific gravity,and elapsed time-to-failure.Condi-tioning of test material in controlled atmospheres,determina-tion of depth of knife checks(when applicable),and determi-nation of percent of wood an
