TFEC 1-2019 Standard for Design of Timber Frame Structures and Commentary TFEC 1-2019 Standard Page 1 January 2019 TFEC 1-2019 Standard for Design of Timber Frame Structures and Commentary Timber Frame Engineering Council Technical Activities Committee (TFEC-TAC) Contributing Authors: Jim DeStefano Jeff Hershberger Tanya Luthi Jaret Lynch Tom Nehil Dick Schmidt, Chair Rick Way Copyright © 2019, All rights reserved. Timber Framers Guild 1106 Harris Avenue, Suite 303 Bellingham, WA 98225 TFEC 1-2019 Standard Page 2 January 2019 Table of Contents 1.0 General Requirements for Structural Design and Construction .......................................6 1.1 Applicability and Scope ........................................................................................ 6 1.2 Liability ................................................................................................................. 6 1.3 General Requirements ........................................................................................... 7 1.3.1 Strength ........................................................................................................... 7 1.3.2 Serviceability ................................................................................................... 7 1.3.3 General Structural Integrity ............................................................................. 7 1.3.4 Conformance with Standards .......................................................................... 7 1.4 Design Loads ......................................................................................................... 8 1.4.1 Governed by Codes ......................................................................................... 8 1.4.2 Loads Included ................................................................................................ 8 1.5 Construction Documents ....................................................................................... 8 1.5.1 Types of Documents........................................................................................ 8 1.5.2 Material Selection ........................................................................................... 8 1.5.3 Member Sizes .................................................................................................. 8 1.5.4 Connection Details .......................................................................................... 8 1.6 Materials ................................................................................................................ 9 1.6.1 Sawn Timber ................................................................................................... 9 1.6.2 Structural Glued Laminated Timber ............................................................... 9 1.6.3 Wood Pegs....................................................................................................... 9 1.6.4 Wood Wedges ............................................................................................... 10 1.6.5 Splines ........................................................................................................... 10 1.7 Notation ............................................................................................................... 10 2.0 Structural Members .........................................................................................................12 TFEC 1-2019 Standard Page 3 January 2019 2.1 General ................................................................................................................ 12 2.2 Seasoning Effects ................................................................................................ 12 2.3 Notching .............................................................................................................. 12 2.3.1 Effects on Member Stiffness ......................................................................... 12 2.3.2 Tension or Compression Face Notches ......................................................... 12 2.3.3 Coped Tension Face Notches ........................................................................ 13 2.3.4 Partial-width Notches .................................................................................... 13 3.0 Connections.....................................................................................................................15 3.1 General ................................................................................................................ 15 3.1.1 Terminology .................................................................................................. 15 3.1.2 Installation of Pegs ........................................................................................ 16 3.1.3 Installation of Wedges ................................................................................... 16 3.1.4 Connection Design ........................................................................................ 16 3.2 Withdrawal .......................................................................................................... 16 3.2.1 Prohibition of Withdrawal Loading .............................................................. 16 3.3 Mortise and Tenon Connections Loaded in Shear .............................................. 17 3.3.1 Load Transfer by Direct Bearing .................................................................. 17 3.3.2 Shear Capacity............................................................................................... 17 3.3.3 Strength Contribution of Pegs ....................................................................... 17 3.3.4 Connection Detailing..................................................................................... 17 3.4 Mortise and Tenon Connections Loaded in Tension .......................................... 17 3.4.1 Yield Limit Equations ................................................................................... 17 3.4.2 Dowel Bearing Strength ................................................................................ 18 3.4.3 Dowel Bearing Strength at an Angle to Grain .............................................. 19 3.4.4 Dowel Bearing Length .................................................................................. 19 TFEC 1-2019 Standard Page 4 January 2019 3.4.5 Bending Yield Strength of Pegs .................................................................... 19 3.4.6 Peg Diameter ................................................................................................. 20 3.4.7 Seasoning and Creep Effects ......................................................................... 20 3.4.8 Edge Distance, End Distance and Spacing.................................................... 20 3.4.9 Adjustment Factors for Peg Connections ...................................................... 21 3.4.10 Tenon Size and Quality ............................................................................... 22 3.4.11 Mortise Placement ....................................................................................... 22 3.5 Seasoning Effects ................................................................................................ 23 3.6 Bearing Connections Inducing Block Shear ....................................................... 23 4.0 Design for Lateral Loads ................................................................................................24 4.1 Stand-Alone Timber Frames ............................................................................... 24 4.1.1 Serviceability Considerations ........................................................................ 24 4.1.2 Seismic Design Criteria ................................................................................. 24 4.2 Timber Frames and Diaphragm/Shearwall Systems ........................................... 24 4.2.1 Coupled Timber Frame and Diaphragm/Shearwall Systems ........................ 25 4.2.2 Timber Frame Gravity-Only Systems ........................................................... 25 Appendix A Glossary .........................................................................................................26 References .............................................................................................................................28 TFEC 1-2019 Standard Page 5 January 2019 Standard for Design of Timber Frame Structures 1.0 General Requirements for Structural Design and Construction 1.1 Applicability and Scope This Standard defines the engineering and design requirements for timber frame construction. A timber frame shall be regarded as a structural building frame system or a portion thereof that is composed of timber members in which connections between interlocking members are created principally by carpenter-style wood joinery, often using wood pegs and wood wedges, possibly supplemented with metal fasteners. This Standard is not intended to preclude use of materials, assemblies, structures or designs not meeting the criteria herein, provided it is demonstrated by analysis based on recognized theory, full scale or prototype loading tests, studies of model analogues or extensive experience in use that the material, assembly, structure or design will perform satisfactorily in its intended end use. This Standard is intended as a supplement to provisions of the National Design Specification for Wood Construction (ANSI/AWC NDS ©, Ref. 4). In the event of conflicts or contradictory requirements between this Standard