Timber Frame Tension Joinery - Timber Frame Engineering Council

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Studies in the U. S. that adapt and apply the European yield model to domestic practice for bolted connections are reported in (Thangjitham, 1981; McLain and Thangjitham, 1983; Soltis et al., 1986; Soltis et al., 1987; Soltis and Wilkinson, 1987; Wilkinson, 1993). Technical literature on timber frame joinery design is limited. Reviews of current practice, which is based on interpretations of past research and available design standards, are found in (Brungraber, 1992a; Brungraber, 1992b). Alternatives to all-wood joinery involving metallic fasteners are described in (Brungraber, 1992a) and (Duff et al., 1996). There are several craft-oriented books that present the history, architectural design, and construction techniques for timber frames. These include (Elliot and Wallas, 1977; Benson and Gruber, 1980; Sobon and Schroeder, 1984; Benson, 1997; Sobon 1994). In these books, details related to engineering design are usually limited to span tables for bending members (floor beams). Carpentry details of Oriental joinery are found in (Seike, 1977). Even though the joinery used in timber-frame structures resembles that used by carpenters in the furniture industry, significant differences exist. The basic mortise and tenon joint used in furniture construction (Hill and Eckelman, 1973) includes a relatively short (stub) tenon and relies on adhesives to secure the joint. Doweled joints in furniture (Eckelman, 1970; 1979) use the wood dowel as a replacement for the tenon, rather than as an anchor to prevent tenon withdrawal from the mortise. These joints also rely on adhesives to secure the joint. Hence, the relatively large body of literature in furniture joinery is not applicable to the structural systems considered here. 9
3. European Yield Model and Proposed Additions 3.1 Introduction Today, the craft of timber framing is returning. Craftsmen are re-learning the skills of the trade by studying existing buildings and applying the techniques to modern construction. Building officials, however, are often not familiar with this construction method and will not rely on previous standards for today’s practices. The problem is not in the structural members, for the behavior of beams and columns is well understood, but in the timber-frame connections. A method to determine the strength of these connections is therefore required. This chapter will focus on the existing yield model and its derivation and will determine how it could be applied to timber-frame connections. An alternate analysis of one of the yield modes is shown and was used to determine its applicability to pegged mortise and tenon connections. As a result of this analysis, additional yield modes are introduced, specific to pegged mortise and tenon connections. 3.2 Development of European Yield Model A mathematical model for determining connection strength was developed in 1941 by K. W. Johansen, who applied the theory to connections with metal dowel fasteners (Aune and Patton-Mallory, 1986). This model was used to analyze single and double shear timber connections that used bolts as the primary fasteners. To analyze the connections, Johansen compared the dowel bearing strength of the bolt to its bending strength to obtain the overall strength of the connection (Johansen, 1949). H. J. Larsen extended Johansen’s development to include various failure modes for single and double shear connections (Larsen, 1973). Figures 3-1 and 3-2 illustrate the various failure modes for single and double shear connections. Labeling of the modes follows National Design Specification for Wood 10
Page 1 and 2: TIMBER FRAME TENSION JOINERY Richar
Page 3 and 4: Acknowledgments Acknowledgments go
Page 5 and 6: 5.4 Dowel Bearing Test Results.....
Page 7 and 8: List of Figures Page Figure 1-1 Typ
Page 9 and 10: List of Appendices Page Appendix A
Page 11 and 12: elasto-plastic behavior an ideal yi
Page 13 and 14: normal distribution orthotropic mat
Page 15 and 16: xiii
Page 17 and 18: Tie Beam Figure 1-2 American Timber
Page 19 and 20: 2. Timber Framing Background 2.1 Hi
Page 21 and 22: territories. Using the new construc
Page 23: Although timber framing is still a
Page 27 and 28: strength, then the dowel could bend
Page 29 and 30: P III s = k3 ⋅D⋅ts ⋅F ( 2 + R
Page 31 and 32: The areas under the shear diagram c
Page 33 and 34: and F es = 1728 psi) (see Sections
Page 35 and 36: Figure 3-7 Combined Shear - Bending
Page 37 and 38: 3.5 Additional Yield Model Equation
Page 39 and 40: need to know the required load and
Page 41 and 42: Using the equivalent bolt diameter,
Page 43 and 44: 4. Peg Testing Procedures and Analy
Page 45 and 46: dowel diameter and the intercept of
Page 47 and 48: were taken for two orientations (e.
Page 49 and 50: affected by the deformation in the
Page 51 and 52: Figure 4-6 Orientation of Prelimina
Page 53 and 54: The main purpose of the full-size t
Page 55 and 56: 5. Test Results 5.1 Introduction Th
Page 57 and 58: Table 5-1 Bending Test Correlation
Page 59 and 60: Table 5-4 Bending Yield Strength Re
Page 61 and 62: 5.3 Shear Test Results 181 shear te
Page 63 and 64: 0.90 0.90 Specific Gravity 0.80 0.7
Page 65 and 66: Yield Stress τ (psi.) 3/4" Red Oak
Page 67 and 68: 5.4 Dowel Bearing Test Results The
Page 69 and 70: obtained from shear tests at variou
Page 71 and 72: To obtain allowable stress design v
Page 73 and 74: l e l v Figure 6-1 Full-size Test D
Page 75 and 76:
each mode in the general yield mode
Page 77 and 78:
7. Conclusions and Recommendations
Page 79 and 80:
Appendix A Derivation of Dowel Rota
Page 81 and 82:
Appendix C NDS Yield Mode II, Alter
Page 83 and 84:
Appendix D NDS Mode III s , Alterna
Page 86 and 87:
Appendix E Standard Test Setup for
Page 88 and 89:
Appendix G Bending Test Data Summar
Page 90 and 91:
Summary of Bending Tests: Last Revi
Page 92 and 93:
Appendix H Shear Test Data Summary
Page 94 and 95:
Summary of 1-1/4" Red Oak Shear Tes
Page 96 and 97:
Summary of 1" White Oak Shear Tests
Page 98 and 99:
Appendix I Dowel Bearing Data Summa
Page 100 and 101:
Bibliography Abe M., and Kawaguchi,
Page 102:
Soltis, L. A.; Karnasudirdja, S.; L
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