1、Standard Specification for Wood Products AASHTO Designation: M 168-07 (2016)1Release: Group 2 (June 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4e M 168-1 AASHTO Standard Specification for Wood Products A
2、ASHTO Designation: M 168-07 (2016)1Release: Group 2 (June 2016) 1. SCOPE 1.1. This specification provides a compilation of specifications covering commercial grades and species of lumber and other wood products for highway construction as indicated below. More detailed requirements will be found in
3、the various specifications cited for specific products: 1.1.1. Lumber, 1.1.2. Structural glued laminated timber, 1.1.3. Piling, 1.1.4. Posts, and 1.1.5. Structural composite lumber. 1.2. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards a
4、nd Publications: M 133, Preservatives and Pressure Treatment Processes for Timber AASHTO LRFD Bridge Design Specifications Standard Specifications for Highway Bridges, Division I 2.2. ASTM Standards: D9, Standard Terminology Relating to Wood and Wood-Based Products D25, Standard Specification for Ro
5、und Timber Piles D245, Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber D1165, Standard Nomenclature of Commercial Hardwoods and Softwoods D1990, Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumb
6、er from In-Grade Tests of Full-Size Specimens D2555, Standard Practice for Establishing Clear Wood Strength Values D3737, Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam) D5456, Standard Specification for Evaluation of Structural Composite Lumber
7、 Products D6570, Standard Practice for Assigning Allowable Properties for Mechanically Graded Lumber 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e M 168-2 AASHTO 2.3. AASHTO, American Road and T
8、ransportation Builders Association (ARTBA), The Associated General Contractors of America (AGC) Publication: A Guide to Standardized Highway Barrier Hardware 2.4. National Institute of Standards and Technology (NIST) Standard: Voluntary Product Standard PS 20, American Softwood Lumber Standard 2.5.
9、Joint ANSI/AITC Standard: ANSI/AITC A 190.1, Structural Glued Laminated Timber 3. TERMINOLOGY 3.1. boardlumber that is less than 38 mm standard (2 in. nominal) thickness and greater than 38 mm standard (2 in. nominal) width. Boards less than 140 mm standard (6 in. nominal) width are sometimes called
10、 strips. 3.2. dimensionlumber with a thickness from 38 mm standard (2 in. nominal) up to but not including 114 mm standard (5 in. nominal) and a width of greater than 38 mm standard (2 in. nominal). 3.3. dressed lumberlumber that has been planed (surfaced). 3.4. factory and shop lumberlumber intende
11、d to be cut up for use in further manufacture. It is graded on the percentage of the area that will produce a limited number of cuttings of a specified minimum size and quality. 3.5. grading rules-writing agencyorganizations that write and publish grading rules for lumber based on NIST PS 20 guideli
12、nes and that are accredited by the American Lumber Standards Committee Board of Review or a nationally recognized equivalent system. 3.6. hardwoodgenerally, one of the commercial species groups or one of the botanical groups of trees that have vessels or pores and broad leaves, in contrast to the co
13、nifers or softwoods. The term has no reference to actual hardness of the wood. 3.7. heartwoodthe wood extending from the pith to the sapwood, the cells of which no longer participate in the life process of the tree. Heartwood may contain phenolic compounds, gums, resins, and other materials that usu
14、ally make it darker and more decay resistant than sapwood. 3.8. lumberthe product of the saw and planing mill for which manufacturing is limited to sawing, resawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching. Lumber may be made from either softwood o
15、r hardwood. 3.9. lumber gradequality designation of lumber established in accordance with established grading rules developed and adopted by grading rules-writing agencies, which is certified by either the American Lumber Standards Committee Board of Review or a nationally recognized equivalent syst
16、em. 3.10. nominal sizeas applied to timber or lumber, the size by which it is known and sold in the market (often differs from actual size). 3.11. rough lumberlumber that has not been dressed (surfaced) but has been sawed, edged, and trimmed. 3.12. softwood (conifers)generally, one of the botanical
17、groups of trees that have needle-like or scale-like leaves. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e M 168-3 AASHTO 3.13. stress-graded lumberlumber that has been graded based on grading ru
18、les developed, adopted, and published by grading rules-writing agencies that have been certified by the American Lumber Standards Committee Board of Review or an equivalent system; or lumber having assigned working stresses and modulus of elasticity values in accordance with accepted basic principle
19、s of strength grading and the provisions of NIST PS 20. 3.14. structural composite lumberlumber that is a reconstituted (manufactured) lumber product for structural applications, which is either laminated veneer lumber or parallel strand lumber bonded with an exterior adhesive. 3.15. structural glue
20、d laminated timberan engineered, stress-rated product of a timber laminating plant, comprising assemblies of specially selected and prepared wood laminations securely bonded together with adhesives. The grain of all laminations is approximately parallel longitudinally. The laminations may be compose
21、d of pieces end joined to form any length, of pieces placed or bonded edge to edge to make any width, or of pieces bent to curved form during bonding.structural lumberlumber that is intended for use where allowable properties are required. The structural lumber grade is based on the strength or stif
22、fness of the piece as related to anticipated use. 3.16. timberlumber that is standard 114 mm (nominal 5 in.) or more in the least dimension. 3.17. worked lumberlumber that has been dressed, matched, shiplapped, and/or patterned. 3.18. yard lumbera little-used term for lumber of all sizes and pattern
23、s that is intended for general building purposes and that has no design property requirements. 3.19. other wood or wood-based product related terminology and definitionsfor other general terminology and definitions related to wood or wood-based products, other than those listed above, refer to ASTM
24、D9. 4. CLASSIFICATION 4.1. Species of Wood: 4.1.1. The standard commercial and botanical names of the species of wood recognized in this specification are as described in ASTM D1165. 4.1.1.1. Some species may be covered under more than one set of grading rules. In such cases, the applicable grading
25、rules shall be as specified in the contract. 4.1.1.2. Some grading rules provide for the inclusion of additional species under the established commercial name of the lumber. 4.1.2. Limitation of Use: 4.1.3. Wood for structural purposes shall not be used in exposed permanent structures without pressu
26、re impregnation of a preservative in accordance with M 133. 4.1.3.1. The heartwood of the following species is high in decay resistance and, when specified, may be used without preservative treatment: 2016 by the American Association of State Highway and Transportation Officials. All rights reserved
27、. Duplication is a violation of applicable law.TS-4e M 168-4 AASHTO Softwoods Hardwoods Bald Cypress, old growth Chestnut Cedar Locust, black Juniper Oak, white Redwood, old growth Osage, orange Yew, Pacific Walnut, black 4.2. Hardwoods: 4.2.1. GradingLumber from hardwood species shall be graded in
28、accordance with grading rules that conform to the basic provision of NIST PS 20 and that are developed, adopted, and published by grading rules-writing agencies that are certified by the American Lumber Standards Committee Board of Review or a nationally recognized equivalent system. 4.2.1.1. Hardwo
29、od lumber, which is intended for structural use with design stress, shall be stress-graded lumber that is graded in conformance with nationally accepted standards such that the lumber will meet the required stress values listed in Section 13.2 Division I of the AASHTO Standard Specifications for Hig
30、hway Bridges or in Section 8.4 of the AASHTO LRFD Bridge Design Specifications. 4.2.2. ClassificationHardwood lumber shall be classified and stress-grade marked according to the use, manufacturing, and size classification listed in NIST PS 20 as outlined below. 4.2.2.1. Use classification shall be Y
31、ard Lumber, Structural Lumber, and Factory and Shop Lumber. 4.2.2.2. Manufacturing classification shall be Rough Lumber, Dressed (Surfaced) Lumber, and Worked Lumber. 4.2.2.3. Size classification shall be Nominal Size Designations of Boards, Dimension, and Timbers; Rough Dry Sizes; and Dressed Sizes
32、. 4.2.3. Stress GradingAs appropriate, either ASTM D245, ASTM D1990, ASTM D2555, or ASTM D6570 and/or other equivalent nationally recognized technical standards shall be used to develop working stress and modulus of elasticity values for Stress-Graded Structural Lumber. 4.2.3.1. Design values develo
33、ped by grading rules agencies may be used provided they were developed in accordance with nationally accepted standards. The purchaser may request a report from the rules- writing agency explaining how the design values of working stress and modulus of elasticity were derived. 4.3. Softwoods: 4.3.1.
34、 GradingLumber from softwood species shall be graded in accordance with grading rules that conform to the basic provisions of NIST PS 20 and are developed, adopted, and published by grading rules-writing agencies that are certified by the American Lumber Standards Committee Board of Review or a nati
35、onally recognized equivalent system. 4.3.1.1. Softwood lumber that is intended for structural use with design stress shall be stress-graded lumber that is graded in conformance with nationally accepted standards such that the lumber will meet the required stress values listed in Section 13.2, Divisi
36、on I of the AASHTO Standard Specifications for Highway Bridges or in Section 8.4 of the AASHTO LRFD Bridge Design Specifications. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e M 168-5 AASHTO 4.3
37、.2. ClassificationSoftwood lumber shall be classified and stress-graded marked according to the use, manufacturing, and size classifications listed in NIST PS 20 as outlined below. 4.3.2.1. Use classifications shall be Yard Lumber, Structural Lumber, and Factory and Shop Lumber. 4.3.2.2. Manufacturi
38、ng classifications shall be Rough Lumber, Dressed (Surfaced) Lumber, and Worked Lumber. 4.3.2.3. Size classifications shall be Nominal Size Designations of Boards, Dimension, and Timbers; Rough Dry Sizes; and Dressed Sizes. 4.3.3. Stress GradingAs appropriate, either ASTM D425, ASTM D1990, ASTM D255
39、5, or ASTM D6570 and/or other equivalent nationally recognized technical standards shall be used to develop working stress and modulus of elasticity values for Stress-Graded Structural Lumber. 4.3.3.1. Design values developed by grading rules agencies may be used provided they were developed in acco
40、rdance with nationally accepted standards. The engineer may request a report from the rules-writing agency explaining how the design values of working stress and modulus of elasticity were derived. 4.4. Structural Composite Lumber: 4.4.1. ASTM D5456 or equivalent nationally recognized standard shall
41、 be used to develop working stresses and modulus values for structural composite lumber; however, the values shall not be less than the minimum values as specified by the AASHTO Standard Specifications for Highway Bridges or AASHTO LRFD Bridge Design Specifications. 4.5. Structural Glued Laminated T
42、imber: 4.5.1. ASTM D3737 or equivalent nationally recognized standard shall be used to develop working stresses and modulus values for structural glued laminated timber; however, the values shall not be less than the minimum values as specified by the AASHTO Standard Specifications for Highway Bridg
43、es or AASHTO LRFD Bridge Design Specifications. 5. PRODUCTS 5.1. Lumber: 5.1.1. All lumber shall conform with the applicable softwood or hardwood lumber grading standards. The following requirements shall be specified in the purchase order: 5.1.1.1. The nominal dimensions: thickness, width, and leng
44、th of each item required; 5.1.1.2. The grade required or the stress-grade rating of lumber required, including any special requirements, such as provisions for heartwood content, freedom from wane, seasoning condition, etc.; 5.1.1.3. Manufacturing classification such as rough, dressed, or worked lum
45、ber; 5.1.1.4. The allowable species according to standard commercial name; 5.1.1.5. The name of the agency that will be responsible for grading, inspecting, and grade marking the lumber; 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication
46、is a violation of applicable law.TS-4e M 168-6 AASHTO 5.1.1.6. The year of issue of the applicable grading rules; and 5.1.1.7. Preservative treatment required. 5.2. Structural Glued Laminated Timber: 5.2.1. Requirements for the dimensions, grade combinations, lumber for laminating, appearance grades
47、, adhesives, and laminating of structural glued laminated timber as well as inspection and test procedures, marking, and the certification by a qualified inspection and testing agency shall be in conformance with ANSI/AITC A 190.1. Species, grade, and design values for Structural Glued Laminated Tim
48、ber shall conform to the AASHTO Standard Specifications for Highway Bridges or AASHTO LRFD Bridge Design Specifications. 5.3. Piling: 5.3.1. Round timber piles shall conform to ASTM D25. 5.4. Posts: 5.4.1. Posts shall be of sound wood, free of decay, excessive knots, and insect attack, and shall oth
49、erwise conform to the provisions of this specification. 5.4.1.1. Fence PostsPosts shall be preservative-treated in accordance with Section 4.1.2 except where the contract plans permit use of decay-resistant varieties. Posts to be driven shall be machine-pointed prior to treatment. 5.4.1.2. Guardrail PostsGuardrail posts shall be a stress grade of 8.2 MPa (1200 psi) or more, conforming to the applicable standards contained in AASHTO-ARTBA-AGC, A Guide to Standardized Highway Barrier Hardware. When a preservative is required, fr
