Load Duration and Seasoning Effects on Mortise & Tennon Joinery

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Douglas Fir Moisture Contents MC % 20 18 16 14 12 10 8 6 4 2 0 0 50 100 150 200 250 300 350 Time (Days) Figure 4-5 Douglas Fir Moisture Content Douglas Fir Moisture Content 20 18 16 14 Moisture Content (%) 12 10 8 6 4 2 0 0 50 100 150 200 250 300 350 Time (Days) Figure 4-6 Douglas Fir Mean Moisture Content 41
4.2.3. Results <strong>and</strong> Conclusions of Time-Deflection Behavior As can be seen from Figure 4-4 the deflection rate of the joints slowed to nearly zero after approximately 225 days. A slight amount of creep continued until the conclusion of the long-term testing. Comparison of Figure 4-2 <strong>and</strong> Figure 4-3 reveals that joints with high initial flexibility also experienced more creep <strong>and</strong> shrinkage deflection than those with high initial stiffness. Since the materials used in construction of the joints were as identical as possible, this suggests that variations in fabrication <strong>and</strong> assembly (cutting tolerances) have a major influence on both initial <strong>and</strong> long-term deflections of mortise <strong>and</strong> tenon joints in tension. The plot in Figure 4-7 shows the average deflection of the drawbored <strong>and</strong> the nondrawbored joints. Drawboring had a significant effect on the initial deflection when the load was applied; the initial deflections of the drawbored joints were substantially less than those of the non-drawbored joints. Drawboring also reduced the creep rate. Longterm deflection for the drawbored joints averaged about 20% less than that of the nondrawbored joints. 42
Page 1 and 2: LOAD DURATION AND SEASONING EFFECTS
Page 3 and 4: Acknowledgments This report is base
Page 5 and 6: 5.5.1. Joint Properties ...........
Page 7 and 8: List of Tables Page Table 2-1 Easte
Page 9 and 10: ugged traditional style has helped
Page 11 and 12: 1.3. Literature Review Previous res
Page 13 and 14: However these failures were away fr
Page 15 and 16: 1.5. Overview Primary among the thr
Page 17 and 18: 2. Joint Tests (Eastern White Pine)
Page 19 and 20: Figure 2-2 Short Term Test Set-up f
Page 21 and 22: Figure 2-3 Typical Mortise Member F
Page 23 and 24: offset horizontally a distance of 5
Page 25 and 26: 2.7. Dowel Bearing Strength Dowel b
Page 27 and 28: 2.8. Detailing Requirements (End/Ed
Page 29 and 30: Figure 2-9 Illustration of Peg Fail
Page 31 and 32: properties of a base material loade
Page 33 and 34: ut the load is applied through the
Page 35 and 36: Table 3-2 Spring Theory Summary Tes
Page 37 and 38: the stiffer of the two materials; r
Page 39 and 40: 4. Long Term Seasoning</str
Page 41 and 42: of the calibration markings were ob
Page 43 and 44: appropriate location for the center
Page 45 and 46: Table 4-1 Douglas Fir Long-Term Joi
Page 47: Normalized Douglas Fir 0.25 0.20 1.
Page 51 and 52: 4.3. Southern Yellow Pine Twenty-on
Page 53 and 54: Southern Yellow Pine 0.160 Deflecti
Page 55 and 56: Southern Yellow Pine Moisture Conte
Page 57 and 58: Normalized Southern Yellow Pine 0.0
Page 59 and 60: 2.0D end distance and</stro
Page 61 and 62: two pegs was active in carrying the
Page 63 and 64: Normalized White Oak 0.25 0.20 Defl
Page 65 and 66: White Oak 40 35 30 Moisture Content
Page 67 and 68: loaded to 1000 lb which is 16% of t
Page 69 and 70: with only one joint it is difficult
Page 71 and 72: 4.5.2. Moisture Content The eastern
Page 73 and 74: Eastern White Pine 0.30 0.25 0.20 D
Page 75 and 76: 5. Failure Testing of Long Term Spe
Page 77 and 78: earing test samples were oriented i
Page 79 and 80: 5.3.2. Material Properties (Dowel B
Page 81 and 82: twelve joints had white oak pegs <s
Page 83 and 84: the load-deflection plots shown in
Page 85 and 86: 6.2. Modification to minimum end <s
Page 87 and 88: unloaded. Therefore, the Madison Cu
Page 89 and 90: 7. References AFPA, (1997). “Nati
Page 91 and 92: Load-Deflection Pl
Page 93 and 94: Dowel Bearing Test Results Test Num
Page 95 and 96: Peg Specific Gravity and</s
Page 97 and 98: Load-Deflection Pl
Page 99 and 100:
SYP 35 SYP 36 9000 4000 3760.44 800
Page 101 and 102:
Specific Gravity and</stron
Page 103 and 104:
Appendix C (white oak) 7.1.1. Joint
Page 105 and 106:
WO 27 WO 28 7000 6000 6474.64 9000
Page 107 and 108:
WO 43 WO 44 12000 10000 16000 14000
Page 109 and 110:
Page 111 and 112:
Appendix D (eastern white pine) oin
Page 113 and 114:
EWP 27 EWP 28 12000 8000 7579.80 10
Page 115 and 116:
EWP 43 EWP 44 9000 8000 7000 5000 4
Page 117 and 118:
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Load Duration and Seasoning Effects on Mortise & Tennon Joinery

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