1、Designation: D 7199 07Standard Practice forEstablishing Characteristic Values for Reinforced GluedLaminated Timber (Glulam) Beams Using Mechanics-BasedModels1This standard is issued under the fixed designation D 7199; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers mechanics-based requirements forcalculating chara
3、cteristic values for the strength and stiffness ofreinforced structural glued laminated timbers (glulam) manu-factured in accordance with applicable provisions of ANSI/AITC A190.1, subjected to quasi-static loadings. It addressesmethods to obtain bending properties parallel to grain, aboutthe x-x ax
4、is (Fbxand Ex) for horizontally-laminated reinforcedglulam beams. Secondary properties such as bending about they-y axis (Fby), shear parallel to grain (Fvxand Fvy), tensionparallel to grain (Ft), compression parallel to grain (Fc), andcompression perpendicular to grain (Fc) are beyond the scopeof t
5、his practice. When determination of secondary properties isdeemed necessary, testing according to other applicable meth-ods, such as Test Methods D 143, D 198 or analysis inaccordance with Practice D 3737, is required to establish thesesecondary properties. Reinforced glulam beams subjected toaxial
6、loads are outside the scope of this standard. This practicealso provides minimum test requirements to validate themechanics-based model.1.2 The practice also describes a minimum set ofperformance-based durability test requirements for reinforcedglulams, as specified in Annex A1. Additional durabilit
7、y testrequirements shall be considered in accordance with thespecific end-use environment. Appendix X1 provides an ex-ample of a mechanics-based methodology that satisfies therequirements set forth in this standard.1.3 Characteristic strength and elastic properties obtainedusing this standard may be
8、 used as a basis for developingdesign values. However, the proper safety, serviceability andadjustment factors including duration of load, to be used indesign are outside the scope of this standard.1.4 This practice does not cover unbonded reinforcement,prestressed reinforcement, nor shear reinforce
9、ment.1.5 The values stated in SI units are to be regarded asstandard. The mechanics based model may be developed usingSI or in.-lb units.1.6 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 e
10、stablish 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 143 Test Methods for Small Clear Specimens of TimberD 198 Test Methods of Sta
11、tic Tests of Lumber in StructuralSizesD 905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD 1990 Practice for Establishing Allowable Properties forVisually-Graded Dimension Lumber from In-Grade Testsof Full-Size SpecimensD 2559 Specification for Adhesives for St
12、ructural Lami-nated Wood Products for Use Under Exterior (Wet Use)Exposure ConditionsD 2915 Practice for Evaluating Allowable Properties forGrades of Structural LumberD 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite MaterialsD 3410/D 3410M Test Method for Compressive Prop
13、ertiesof Polymer Matrix Composite Materials with UnsupportedGage Section by Shear LoadingD 3737 Practice for Establishing Allowable Properties forStructural Glued Laminated Timber (Glulam)D 4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural Material1This practice is under
14、the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.02 on Lumber and EngineeredWood Products.Current edition approved July 1, 2007. Published July, 2007. Originally approvedin 2006. Last previous edition approved in 2006 as D 7199 06.2For referenced AST
15、M 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 Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
16、cken, PA 19428-2959, United States.D 5124 Practice for Testing and Use of a Random NumberGenerator in Lumber and Wood Products Simulation2.2 Other Standard:ANSI/AITC A190.1 Structural Glued Laminated Timber33. Terminology3.1 DefinitionsStandard definitions of wood terms aregiven in Terminology D9and
17、 standard definitions of structuralglued laminated timber terms are given in Practice D 3737.3.2 Definitions of Terms Specific to This Standard:3.2.1 bonded reinforcementa reinforcing material that iscontinuously attached to a glulam beam through adhesivebonding.3.2.2 bumper laminationa wood laminat
18、ion continuouslybonded to the outer side of reinforcement.3.2.3 compression reinforcementreinforcement placed onthe compression side of a flexural member.3.2.4 conventional wood lamstocksolid sawn wood lami-nations with a net thickness of 2 in. or less, graded eithervisually or through mechanical me
19、ans, finger-jointed andface-bonded to form a glulam.3.2.5 development lengththe length of the bond line alongthe axis of the beam required to develop the design tensilestrength of the reinforcement.3.2.6 fiber-reinforced polymer (FRP)any material consist-ing of at least two distinct components: rein
20、forcing fibers anda binder matrix (a polymer). The reinforcing fibers are permit-ted to be either synthetic (for example, glass), metallic, ornatural (for example, wood), and are permitted to be long andcontinuously-oriented, or short and randomly oriented. Thebinder matrix is permitted to be either
21、 thermoplastic (forexample, polypropylene or nylon) or thermosetting (for ex-ample, epoxy or vinyl-ester).3.2.7 laminating effectan apparent increase of lumberlamination tensile strength because it is bonded to adjacentlaminations within a glulam beam. This apparent increase maybe attributed to a re
22、direction of stresses around knots and graindeviations through adjacent laminations.3.2.8 partial length reinforcementreinforcement that isterminated within the length of the timber.3.2.9 reinforcementany material that is not a conventionallamstock whose mean longitudinal ultimate strength exceeds20
23、 ksi for tension and compression, and whose mean tensionand compression MOE exceeds 3000 ksi, when placed into aglulam timber.Acceptable reinforcing materials include but arenot restricted to: fiber-reinforced polymer (FRP) plates andbars, metallic plates and bars, FRP-reinforced laminated veneerlum
24、ber (LVL), FRP-reinforced parallel strand lumber (PSL).3.2.10 shear reinforcementreinforcement intended to in-crease the shear strength of the beam. This standard does notcover shear reinforcement.3.2.11 tension reinforcementreinforcement placed on thetension side of a flexural member.3.3 Symbols:Ar
25、m = moment arm, distance between compression andtension force couple applied to beam cross-sectionb = beam widthC = total internal compression force within the beam cross-section (see Fig. 2)CFRP = carbon fiber reinforced polymerd = beam depthE = long-span flatwise-bending modulus of elasticity forw
26、ood lamstock (Test Methods D 4761; also see Fig. 1)Fb= allowable bending stress parallel to grain3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.FIG. 1 Typical Stress-Strain Relationship for Wood Lamstock, with Bilinear ApproximationD7199072
27、Fx= internal horizontal force on the beam cross-section (seeEq 2)GFRP = Glass fiber-reinforced polymerLEL = lower exclusion limit (point estimate with 50 %confidence, includes volume factor)LTL = lower tolerance limit (typically calculated with 75 %confidence)Mapplied= external moment applied to the
28、 beam cross-sectionMinternal= internal moment on the beam cross-sectionMC = moisture content (%)MOE = modulus of elasticityMOR = modulus of ruptureMOR5%= 5 % one-sided lower tolerance limit for modulusof rupture, including the volume factorMORBL5%= 5 % one-sided lower tolerance limit for modu-lus of
29、 rupture corresponding to failure of the bumper lamina-tion, including the volume factorm*E = downward slope of bilinear compression stress-straincurve for wood lamstock (see Fig. 1)N.A. = neutral axisT = total internal tension force within the beam cross-section(see Fig. 2)UCS = ultimate compressiv
30、e stress parallel to grainUTS = ultimate tensile stress parallel to grainY = distance from extreme compression fiber to neutral axis(see Fig. 2)y = distance from extreme compression fiber to point ofinterest on beam cross-section (see Fig. 2)ec= strain at extreme compression fiber of beam cross-sect
31、ion (see Fig. 2)ecult= compression strain at lamstock failure (see Fig. 1)ecy= compression yield strain at lamstock UCS (see Fig. 1)etult= tensile strain at lamstock failure (see Fig. 1)e(y) = strain distribution through beam depth (see Fig. 2)r = tension reinforcement ratio (%); cross-sectional are
32、a oftension reinforcement divided by cross-sectional area of beambetween the c.g. of tension reinforcement and the extremecompression fiberr8 = compression reinforcement ratio (%); cross-sectionalarea of compression reinforcement divided by cross-sectionalarea of beam between the c.g. of compression
33、 reinforcementand the extreme tension fibers(y) = stress distribution through beam depth (see Fig. 2)4. Requirements for Mechanics-Based AnalysisMethodologyNOTE 1At a minimum, the mechanics-based analysis shall accountfor: (1) Stress-strain relationships for wood laminations and reinforce-ment; (2)
34、Strain compatibility; (3) Equilibrium; (4) Variability of mechani-cal properties; (5) Volume effects; (6) Finger-joint effects; (7) Laminatingeffects; and (8) Stress concentrations at termination of reinforcement inbeams with partial length reinforcement. In addition to the above factors,characteris
35、tic values developed using the mechanics-based model need tobe further adjusted to address end-use conditions including moistureeffects, duration of load, preservative treatment, temperature, fire, andenvironmental effects. The development and application of these addi-tional factors are outside the
36、 scope of this practice. Annex A1 addressesthe evaluation of durability effects. The minimum output requirements forthe analysis are mean MOE (based on gross section) and 5% LTL MORwith 75 % confidence (based on gross section), both at 12 % MC. Theseanalysis requirements are described below.4.1 Stre
37、ss-strain Relationships:4.1.1 Conventional Wood Lamstock:4.1.1.1 The stress-strain relationship shall be establishedthrough in-grade testing following Test Methods D 198 or TestMethods D 4761, or other established relationships as long asthe resulting model meets the criteria established in Section
38、5.Test lamstock shall be sampled in sufficient quantity fromenough sources to insure that the test results are representativeof the lamstock population that will be used in the fabricationof the beams. Follow-up testing shall be performed annually inNOTEA simplified rectangular block stress distribu
39、tion can be used but it must be shown that it accurately represents the stress distribution.FIG. 2 Example of Beam Section with Strain, Stress, and Force DiagramsD7199073order to track changes in lamstock properties over time, so thatthe layup designs may be adjusted accordingly.4.1.1.2 The stress-s
40、train relationship shall be linear in ten-sion. The stress-strain relationship shall be nonlinear in com-pression if compression is the governing failure mode. In thiscase, a bilinear approximation is acceptable, and shall be usedthroughout this standard (see Fig. 1). In the bilinear model bothtensi
41、on and compression MOE shall be permitted to beapproximated by using the long-span flatwise-bending MOEobtained using Test Methods D 4761.InFig. 1, m*E is thedownward slope of the compression stress-strain curve, definedas the best-fit downward line through the point (UCS, ecy)onthe compression stre
42、ss-strain curve. The downward best-fit lineshall be permitted to be terminated at the point where theultimate compressive strain ecuis approximately 1 %.4.1.2 Reinforcement:4.1.2.1 The stress-strain relationship shall be establishedthrough material-level testing in accordance with Test MethodD 3039/
43、D 3039M and D 3410/D 3410M.4.1.2.2 Nonlinearities in the stress-strain relationship shallbe included in the analysis, if present.4.1.2.3 Acceptable stress-strain models for unidirectionalE-glass FRP (GFRP), Aramid, or Carbon FRP (CFRP) intension are linear-elastic. Acceptable models for hybridE-glas
44、s/Carbon composites in tension are linear or bilinear.Acceptable models for mild steel reinforcement are elastic-plastic. Similar models may also apply in compression.4.2 Strain Compatibility:4.2.1 Fig. 2 shows the cross section of a beam with a linearstrain and bilinear stress distribution, with th
45、e neutral axis adistance Y below the top of the beam. Using the extremecompression fiber as the origin, the strain distribution for agiven applied moment (Mapplied) is defined by the equation:ey! 5ec ec* y/Y! (1)4.3 Equilibrium:4.3.1 In order to maintain equilibrium, the cross-sectionshall satisfy t
46、he conditions of horizontal equilibrium (Eq 2),and the internal moment (Minternal) shall equal the externalmoment applied to that cross section (Mapplied) (Eq 3). See Fig.2 as an example of strain compatibility and equilibrium:(Fx5 0*depthsy!dA 5 0 (2)Mapplied5 Minternal5 Cor T! * Arm 5*depth y * sy
47、! * dA (3)4.4 Variability of Mechanical Properties:4.4.1 The model shall properly account for the variability ofthe mechanical properties of the wood lamstock and the FRPreinforcement. This includes variability of individual proper-ties and correlations among those properties as appropriate.The mech
48、anics-based analysis shall address statistical proper-ties for and correlations between Ultimate Tensile Stress(UTS), Ultimate Compressive Stress (UCS) and long-spanflatwise-bending modulus of elasticity (E). One example ofhow this may be achieved is provided in Appendix X1.4.4.2 These correlation v
49、alues are obtained from test data.Test lamstock shall be sampled in sufficient quantity, fromenough sources to insure that the test results are representativeof the lamstock population that will be used in the fabricationof the beams. Follow-up testing shall be performed annually inorder to track changes in lamstock properties over time, so thatthe layup designs may be adjusted accordingly.4.5 Volume Effects:4.5.1 The model shall properly account for changes in beamstrength properties as affected by beam size. In conventionalglulam, this is achieved by using a
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