Timber Frame Tension Joinery - Timber Frame Engineering Council

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to the dowel and e is the eccentricity of the load; the material thickness and dowel diameter are t and D, respectively; the positions of the dowel pivot point and plastic hinge point are x and Z, respectively; the dowel bearing strength of the base material is F e and the bending yield strength of the dowel is F yb . Equations 3-1 and 3-2 are derived in Appendices A and B, respectively. These equations are applied to each yield mode to determine joint capacity. For instance, the single shear Mode IV has the same type of failure in both the main and side member. Therefore, Eq. 3-2 can be used for each member. From equilibrium, the yield load in each member must be equal, and is the following (Thangjitham, 1981): P= D 2 2F F em ⎛ F 31 ⎜ + ⎝ F yb em es ⎞ ⎟ ⎠ (3-3) The above equation uses F em and F es for the dowel bearing strength in the main (thicker) and side (thinner) members, respectively. The derivation of these equations is based on the assumption that a single, unique position for the eccentricity can be found and that the resultant of the load for the entire connection is at this location. Section 3.3 contains an alternative method for calculating the yield load for Mode IV. The yield loads for the single shear modes are as follows: P D t F I m em m = ⋅ ⋅ (3-4) P D t F I s es s = ⋅ ⋅ (3-5) PII = k1 ⋅D⋅ts ⋅Fes (3-6) P III = k2 ⋅D⋅tm⋅F m ( 1+ 2⋅R ) e em (3-7) 13
P III s = k3 ⋅D⋅ts ⋅F ( 2 + R ) e em (3-8) P IV = D 2 2 ⋅F em ⋅F yb 3⋅ ( 1+ R ) e (3-9) where: k 1 = 2 2 2 3 R + 2⋅R ⋅ ( 1+ R + R ) + R ⋅R − R ⋅ ( 1+ R ) e e t t t e e t ( 1+ R ) e (3-10) k 2 =− Fyb Re D 1 + 2 ⋅ 1 + 2 1 2 R + ⋅ ⋅ ( + ⋅ ) ( e ) ⋅ 2 3⋅F ⋅t em m 2 (3-11) k 3 =− 1+ 2⋅ ( 1+ R F R D e ) 2 yb 2 e + ⋅ ⋅ ( + ) ⋅ 2 R 3⋅F ⋅t e em s 2 (3-12) The other key parameters for these equations are R e which is the ratio of main and side bearing strengths (F em /F es ), and R t which is the ratio of main to side thicknesses (t m /t s ). For the double shear yield modes, simply multiply the single shear yield mode that applies, by two. 3.3 Alternate Derivation of the Mode IV Yield Model Equation As a check on the derivation of the yield model equations, another approach was taken in this research. Instead of looking at the equilibrium of the entire connection, the equilibrium of the dowel was the main concern. An assumed load distribution was to be applied to the dowel for the failure mode in question as a means to obtain a more intuitive derivation (see Figure 3-5). The single shear Mode IV is one that contains two plastic hinges in the dowel. This scenario could occur if the side and main members had high dowel bearing strengths while the peg was flexible. In Figure 3-5, the loading outside of each plastic hinge was unknown so the dowel bearing strength was used arbitrarily. This assumption allowed calculations to be performed 14
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 and 24: Although timber framing is still a
Page 25 and 26: 3. European Yield Model and Propose
Page 27: strength, then the dowel could bend
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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