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Pull-out resistance of self-tapping wood screws with continuous thread Gehloff, Maik 2011

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 PULL-OUT RESISTANCE OF SELF-TAPPING WOOD SCREWS WITH CONTINUOUS THREAD    by MAIK GEHLOFF Dipl.-Ing. (FH), University of Applied Sciences, Eberswalde, Germany, 2002  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) July 2011 ? Maik Gehloff, 2011   ii ABSTRACT Over the past centuries the use of timber in structures has seen waves of decline and rediscovery. Timber structures have evolved from empirical structures using timber within its natural boundaries in terms of shape, size and length to modern day engineering design approach using computers and sophisticated numerical models; this has led to the need of high performance connections in such structures. With the help of mechanical fasteners the envelope was pushed time and time again, creating ever stronger connections. However, the capacity of such connections is not only governed by the mechanical properties of the connectors, but also by the mechanical properties of the connecting wood members. Researchers have been developing different methods of reinforcing the inherent weakness of wood, namely the low strength in tension and compression perpendicular to the grain, as well as the low capacity in longitudinal shear. This thesis examines experimentally the pull-out resistance of self-tapping wood screws with continuous thread, a new type of fastener that can be used as a fastener, but also as reinforcement considering Canadian major wood species. Utilizing its high withdrawal capacity and high tensile strength, this type of connector can potentially be used to transfer internal forces in the wood along the length-axis of the screw instead of loading the wood in its weak directions. The results show that self-tapping wood screws (STSs) have a high resistance to pull-out and are an economical alternative to other reinforcement methods. Besides the superior capacities of STSs in withdrawal and tensile strength to other methods, they are also very easy to install since no pre-drilling of holes is required and thus, give an economical solution to many challenges in engineered timber construction.   iii TABLE OF CONTENTS ABSTRACT ........................................................................................................................ ii TABLE OF CONTENTS ................................................................................................... iii LIST OF TABLES ............................................................................................................. iv LIST OF FIGURES ............................................................................................................ v ACKNOWLEDGEMENTS ............................................................................................. xiii 1. INTRODUCTION ...................................................................................................... 1 1.1. History .................................................................................................................. 1 1.2. Self-tapping wood screws .................................................................................... 7 2. EXPERIMENTAL DESIGN / EQUATIONS .......................................................... 13 2.1. Parameter considerations.................................................................................... 13 2.2. Test setup............................................................................................................ 15 2.3. European code equations .................................................................................... 19 2.4. Equivalency calculations .................................................................................... 22 3. RESULTS / DISCUSSION....................................................................................... 25 3.1. Results ................................................................................................................ 25 3.2. Discussion .......................................................................................................... 36 4. CONCLUSIONS AND RECOMMENDATIONS ................................................... 58 4.1. Conclusions ........................................................................................................ 58 4.2. Recommendations .............................................................................................. 59 BIBLIOGRAPHY ............................................................................................................. 61 APPENDIX ? SUPPLEMENTAL MATERIAL .............................................................. 64   iv LIST OF TABLES Table 1: Effective embedment depths ............................................................................... 18 Table 2: Average densities ................................................................................................ 25 Table 3: Withdrawal test results for 90? ........................................................................... 26 Table 4: Withdrawal test results for 45? ........................................................................... 29 Table 5: Withdrawal test results for 30? ........................................................................... 32 Table 6: Comparison of test results to code equation predictions for STS ....................... 37   v LIST OF FIGURES Figure 1: Development of wood design since 1750............................................................ 2 Figure 2: Knitted glass and aramid fibre fabric (spiral) ...................................................... 4 Figure 3: Transversally reinforced carbon fibre loop ......................................................... 4 Figure 4: Typical load-displacement curve......................................................................... 4 Figure 5: Beam splice using glued-in rods ......................................................................... 6 Figure 6: Screw thread in accordance with DIN 7998 ........................................................ 8 Figure 7: Self-tapping wood screws ................................................................................... 9 Figure 8: Self-tapping wood screw drill-tips ...................................................................... 9 Figure 9: Shank cutter on partially threaded screw ............................................................ 9 Figure 10: STS as embedment and splitting reinforcement .............................................. 11 Figure 11: Test setup for 90? tests ..................................................................................... 15 Figure 12: Test setup for 45? tests ..................................................................................... 16 Figure 13: Test setup for 30? tests ..................................................................................... 16 Figure 14: Transducer to measure deflection .................................................................... 17 Figure 15: Effective embedment depth ............................................................................. 18 Figure 16: Average withdrawal resistance for 6 mm screw @ 90?................................... 27 Figure 17: Average withdrawal resistance for 8 mm screw @ 90?................................... 27 Figure 18: Average withdrawal resistance for 10 mm screw @ 90?................................. 28 Figure 19: Average withdrawal resistance for 6 mm screw @ 45?................................... 30 Figure 20: Average withdrawal resistance for 8 mm screw @ 45?................................... 30 Figure 21: Average withdrawal resistance for 10 mm screw @ 45?................................. 31 Figure 22: Average withdrawal resistance for 6 mm screw @ 30?................................... 33 Figure 23: Average withdrawal resistance for 8 mm screw @ 30?................................... 33   vi Figure 24: Average withdrawal resistance for 10 mm screw @ 30?................................. 34 Figure 25: Typical screw failure ....................................................................................... 34 Figure 26: Typical load deformation plot ......................................................................... 35 Figure 27: Wood density distribution ............................................................................... 36 Figure 28: Comparison of 6 mm results with DIN 1052:2004-8 predictions @ 90? ........ 39 Figure 29: Comparison of 6 mm results with EC 5 predictions @ 90? ............................ 39 Figure 30: Comparison of 6 mm results with DIN 1052:2004-8 predictions @ 45? ........ 40 Figure 31: Comparison of 6 mm results with EC 5 predictions @ 45? ............................ 40 Figure 32: Comparison of 6 mm results with DIN 1052:2004-8 predictions @ 30? ........ 41 Figure 33: Comparison of 6 mm results with EC 5 predictions @ 30? ............................ 41 Figure 34: Comparison of 8 mm results with DIN 1052:2004-8 predictions @ 90? ........ 42 Figure 35: Comparison of 8 mm results with EC 5 predictions @ 90? ............................ 42 Figure 36: Comparison of 8 mm results with DIN 1052:2004-8 predictions @ 45? ........ 43 Figure 37: Comparison of 8 mm results with EC 5 predictions @ 45? ............................ 43 Figure 38: Comparison of 8 mm results with DIN 1052:2004-8 predictions @ 30? ........ 44 Figure 39: Comparison of 8 mm results with EC 5 predictions @ 30? ............................ 44 Figure 40: Comparison of 10 mm results with DIN 1052:2004-8 predictions @ 90? ...... 45 Figure 41: Comparison of 10 mm results with EC 5 predictions @ 90? .......................... 45 Figure 42: Comparison of 10 mm results with DIN 1052:2004-8 predictions @ 45? ...... 46 Figure 43: Comparison of 10 mm results with EC 5 predictions @ 45? .......................... 46 Figure 44: Comparison of 10 mm results with DIN 1052:2004-8 predictions @ 30? ...... 47 Figure 45: Comparison of 10 mm results with EC 5 predictions @ 30? .......................... 47 Figure 46: Comparison of 6 mm results with DIN 1052:2004-8 adjustments @ 90? ...... 49 Figure 47: Comparison of 6 mm results with EC 5 adjustments @ 90? ........................... 49   vii Figure 48: Comparison of 6 mm results with DIN 1052:2004-8 adjustments @ 45? ...... 50 Figure 49: Comparison of 6 mm results with EC 5 adjustments @ 45? ........................... 50 Figure 50: Comparison of 6 mm results with DIN 1052:2004-8 adjustments @ 30? ...... 51 Figure 51: Comparison of 6 mm results with EC 5 adjustments @ 30? ........................... 51 Figure 52: Comparison of 8 mm results with DIN 1052:2004-8 adjustments @ 90? ...... 52 Figure 53: Comparison of 8 mm results with EC 5 adjustments @ 90? ........................... 52 Figure 54: Comparison of 8 mm results with DIN 1052:2004-8 adjustments @ 45? ...... 53 Figure 55: Comparison of 8 mm results with EC 5 adjustments @ 45? ........................... 53 Figure 56: Comparison of 8 mm results with DIN 1052:2004-8 adjustments @ 30? ...... 54 Figure 57: Comparison of 8 mm results with EC 5 adjustments @ 30? ........................... 54 Figure 58: Comparison of 10 mm results with DIN 1052:2004-8 adjustments @ 90? .... 55 Figure 59: Comparison of 10 mm results with EC 5 adjustments @ 90? ......................... 55 Figure 60: Comparison of 10 mm results with DIN 1052:2004-8 adjustments @ 45? .... 56 Figure 61: Comparison of 10 mm results with EC 5 adjustments @ 45? ......................... 56 Figure 62: Comparison of 10 mm results with DIN 1052:2004-8 adjustments @ 30? .... 57 Figure 63: Comparison of 10 mm results with EC 5 adjustments @ 45? ......................... 57 Figure 64: Load ? Deformation (6mm, 4d, 90?, Douglas-fir) .......................................... 64 Figure 65: Load ? Deformation (6mm, 4d, 90?, S-P-F) ................................................... 64 Figure 66: Load ? Deformation (6mm, 4d, 90?, Hemlock) .............................................. 65 Figure 67: Load ? Deformation (6mm, 4d, 45?, Douglas-fir) .......................................... 65 Figure 68: Load ? Deformation (6mm, 4d, 45?, S-P-F) ................................................... 66 Figure 69: Load ? Deformation (6mm, 4d, 45?, Hemlock) .............................................. 66 Figure 70: Load ? Deformation (6mm, 4d, 30?, Douglas-fir) .......................................... 67 Figure 71: Load ? Deformation (6mm, 4d, 30?, S-P-F) ................................................... 67   viii Figure 72: Load ? Deformation (6mm, 4d, 30?, Hemlock) .............................................. 68 Figure 73: Load ? Deformation (6mm, 10d, 90?, Douglas-fir) ........................................ 68 Figure 74: Load ? Deformation (6mm, 10d, 90?, S-P-F) ................................................. 69 Figure 75: Load ? Deformation (6mm, 10d, 90?, Hemlock) ............................................ 69 Figure 76: Load ? Deformation (6mm, 10d, 45?, Douglas-fir) ........................................ 70 Figure 77: Load ? Deformation (6mm, 10d, 45?, S-P-F) ................................................. 70 Figure 78: Load ? Deformation (6mm, 10d, 45?, Hemlock) ............................................ 71 Figure 79: Load ? Deformation (6mm, 10d, 30?, Douglas-fir) ........................................ 71 Figure 80: Load ? Deformation (6mm, 10d, 30?, S-P-F) ................................................. 72 Figure 81: Load ? Deformation (6mm, 10d, 30?, Hemlock) ............................................ 72 Figure 82: Load ? Deformation (6mm, 12d, 90?, Douglas-fir) ........................................ 73 Figure 83: Load ? Deformation (6mm, 12d, 90?, S-P-F) ................................................. 73 Figure 84: Load ? Deformation (6mm, 12d, 90?, Hemlock) ............................................ 74 Figure 85: Load ? Deformation (6mm, 12d, 45?, Douglas-fir) ........................................ 74 Figure 86: Load ? Deformation (6mm, 12d, 45?, S-P-F) ................................................. 75 Figure 87: Load ? Deformation (6mm, 12d, 45?, Hemlock) ............................................ 75 Figure 88: Load ? Deformation (6mm, 12d, 30?, Douglas-fir) ........................................ 76 Figure 89: Load ? Deformation (6mm, 12d, 30?, S-P-F) ................................................. 76 Figure 90: Load ? Deformation (6mm, 12d, 30?, Hemlock) ............................................ 77 Figure 91: Load ? Deformation (6mm, 16d, 90?, Douglas-fir) ........................................ 77 Figure 92: Load ? Deformation (6mm, 16d, 90?, S-P-F) ................................................. 78 Figure 93: Load ? Deformation (6mm, 16d, 90?, Hemlock) ............................................ 78 Figure 94: Load ? Deformation (6mm, 16d, 45?, Douglas-fir) ........................................ 79 Figure 95: Load ? Deformation (6mm, 16d, 45?, S-P-F) ................................................. 79   ix Figure 96: Load ? Deformation (6mm, 16d, 45?, Hemlock) ............................................ 80 Figure 97: Load ? Deformation (6mm, 16d, 30?, Douglas-fir) ........................................ 80 Figure 98: Load ? Deformation (6mm, 16d, 30?, S-P-F) ................................................. 81 Figure 99: Load ? Deformation (6mm, 16d, 30?, Hemlock) ............................................ 81 Figure 100: Load ? Deformation (8mm, 4d, 90?, Douglas-fir) ........................................ 82 Figure 101: Load ? Deformation (8mm, 4d, 90?, S-P-F) ................................................. 82 Figure 102: Load ? Deformation (8mm, 4d, 90?, Hemlock) ............................................ 83 Figure 103: Load ? Deformation (8mm, 4d, 45?, Douglas-fir) ........................................ 83 Figure 104: Load ? Deformation (8mm, 4d, 45?, S-P-F) ................................................. 84 Figure 105: Load ? Deformation (8mm, 4d, 45?, Hemlock) ............................................ 84 Figure 106: Load ? Deformation (8mm, 4d, 30?, Douglas-fir) ........................................ 85 Figure 107: Load ? Deformation (8mm, 4d, 30?, S-P-F) ................................................. 85 Figure 108: Load ? Deformation (8mm, 4d, 30?, Hemlock) ............................................ 86 Figure 109: Load ? Deformation (8mm, 10d, 90?, Douglas-fir) ...................................... 86 Figure 110: Load ? Deformation (8mm, 10d, 90?, S-P-F) ............................................... 87 Figure 111: Load ? Deformation (8mm, 10d, 90?, Hemlock) .......................................... 87 Figure 112: Load ? Deformation (8mm, 10d, 45?, Douglas-fir) ...................................... 88 Figure 113: Load ? Deformation (8mm, 10d, 45?, S-P-F) ............................................... 88 Figure 114: Load ? Deformation (8mm, 10d, 45?, Hemlock) .......................................... 89 Figure 115: Load ? Deformation (8mm, 10d, 30?, Douglas-fir) ...................................... 89 Figure 116: Load ? Deformation (8mm, 10d, 30?, S-P-F) ............................................... 90 Figure 117: Load ? Deformation (8mm, 10d, 30?, Hemlock) .......................................... 90 Figure 118: Load ? Deformation (8mm, 12d, 90?, Douglas-fir) ...................................... 91 Figure 119: Load ? Deformation (8mm, 12d, 90?, S-P-F) ............................................... 91   x Figure 120: Load ? Deformation (8mm, 12d, 90?, Hemlock) .......................................... 92 Figure 121: Load ? Deformation (8mm, 12d, 45?, Douglas-fir) ...................................... 92 Figure 122: Load ? Deformation (8mm, 12d, 45?, S-P-F) ............................................... 93 Figure 123: Load ? Deformation (8mm, 12d, 45?, Hemlock) .......................................... 93 Figure 124: Load ? Deformation (8mm, 12d, 30?, Douglas-fir) ...................................... 94 Figure 125: Load ? Deformation (8mm, 12d, 30?, S-P-F) ............................................... 94 Figure 126: Load ? Deformation (8mm, 12d, 30?, Hemlock) .......................................... 95 Figure 127: Load ? Deformation (8mm, 16d, 90?, Douglas-fir) ...................................... 95 Figure 128: Load ? Deformation (8mm, 16d, 90?, S-P-F) ............................................... 96 Figure 129: Load ? Deformation (8mm, 16d, 90?, Hemlock) .......................................... 96 Figure 130: Load ? Deformation (8mm, 16d, 45?, Douglas-fir) ...................................... 97 Figure 131: Load ? Deformation (8mm, 16d, 45?, S-P-F) ............................................... 97 Figure 132: Load ? Deformation (8mm, 16d, 45?, Hemlock) .......................................... 98 Figure 133: Load ? Deformation (8mm, 16d, 30?, Douglas-fir) ...................................... 98 Figure 134: Load ? Deformation (8mm, 16d, 30?, S-P-F) ............................................... 99 Figure 135: Load ? Deformation (8mm, 16d, 30?, Hemlock) .......................................... 99 Figure 136: Load ? Deformation (10mm, 4d, 90?, Douglas-fir) .................................... 100 Figure 137: Load ? Deformation (10mm, 4d, 90?, S-P-F) ............................................. 100 Figure 138: Load ? Deformation (10mm, 4d, 90?, Hemlock) ........................................ 101 Figure 139: Load ? Deformation (10mm, 4d, 45?, Douglas-fir) .................................... 101 Figure 140: Load ? Deformation (10mm, 4d, 45?, S-P-F) ............................................. 102 Figure 141: Load ? Deformation (10mm, 4d, 45?, Hemlock) ........................................ 102 Figure 142: Load ? Deformation (10mm, 4d, 30?, Douglas-fir) .................................... 103 Figure 143: Load ? Deformation (10mm, 4d, 30?, S-P-F) ............................................. 103   xi Figure 144: Load ? Deformation (10mm, 4d, 30?, Hemlock) ........................................ 104 Figure 145: Load ? Deformation (10mm, 10d, 90?, Douglas-fir) .................................. 104 Figure 146: Load ? Deformation (10mm, 10d, 90?, S-P-F) ........................................... 105 Figure 147: Load ? Deformation (10mm, 10d, 90?, Hemlock) ...................................... 105 Figure 148: Load ? Deformation (10mm, 10d, 45?, Douglas-fir) .................................. 106 Figure 149: Load ? Deformation (10mm, 10d, 45?, S-P-F) ........................................... 106 Figure 150: Load ? Deformation (10mm, 10d, 45?, Hemlock) ...................................... 107 Figure 151: Load ? Deformation (10mm, 10d, 30?, Douglas-fir) .................................. 107 Figure 152: Load ? Deformation (10mm, 10d, 30?, S-P-F) ........................................... 108 Figure 153: Load ? Deformation (10mm, 10d, 30?, Hemlock) ...................................... 108 Figure 154: Load ? Deformation (10mm, 12d, 90?, Douglas-fir) .................................. 109 Figure 155: Load ? Deformation (10mm, 12d, 90?, S-P-F) ........................................... 109 Figure 156: Load ? Deformation (10mm, 12d, 90?, Hemlock) ...................................... 110 Figure 157: Load ? Deformation (10mm, 12d, 45?, Douglas-fir) .................................. 110 Figure 158: Load ? Deformation (10mm, 12d, 45?, S-P-F) ........................................... 111 Figure 159: Load ? Deformation (10mm, 12d, 45?, Hemlock) ...................................... 111 Figure 160: Load ? Deformation (10mm, 12d, 30?, Douglas-fir) .................................. 112 Figure 161: Load ? Deformation (10mm, 12d, 30?, S-P-F) ........................................... 112 Figure 162: Load ? Deformation (10mm, 12d, 30?, Hemlock) ...................................... 113 Figure 163: Load ? Deformation (10mm, 16d, 90?, Douglas-fir) .................................. 113 Figure 164: Load ? Deformation (10mm, 16d, 90?, S-P-F) ........................................... 114 Figure 165: Load ? Deformation (10mm, 16d, 90?, Hemlock) ...................................... 114 Figure 166: Load ? Deformation (10mm, 16d, 45?, Douglas-fir) .................................. 115 Figure 167: Load ? Deformation (10mm, 16d, 45?, S-P-F) ........................................... 115   xii Figure 168: Load ? Deformation (10mm, 16d, 45?, Hemlock) ...................................... 116 Figure 169: Load ? Deformation (10mm, 16d, 30?, Douglas-fir) .................................. 116 Figure 170: Load ? Deformation (10mm, 16d, 30?, S-P-F) ........................................... 117 Figure 171: Load ? Deformation (10mm, 16d, 30?, Hemlock) ...................................... 117   xiii ACKNOWLEDGEMENTS I would like to thank Dr. Frank Lam for his guidance throughout this project and Maximilian Closen as well as the TEAM technicians for the help provided during testing. I would also like to express my gratitude to Natural Sciences and Engineering Research Council of Canada for the financial support in this research project. The cooperation received from Adolf W?rth GmbH & Co. KG (http://www.W?rth.de) for the supply of the ASSY screws and Hans Hundegger - Maschinenbau GmbH (http://www.hundegger.com) for the use of the Hundegger K2 milling machine is also appreciated.     1 1. INTRODUCTION 1.1. History Wood is one of the oldest and most common building materials.  In the past, if wood was not readily available or available in limited quantities then other materials like loam, stone, bamboo etc. were used in buildings.  Wood was primarily used in its natural form and shape, only the development of tools enabled builders to shape wood into desired components and allowed wood to be usable beyond its natural limitations, like length for example. The desire and move toward planned structures was the cradle of timber design and planned timber construction. Until late in the 19th century a timber structure was a mere testimony to craftsmanship and was carried out without structural analysis. These structures were built by empirical considerations and experience only. The first structures fully analyzed by engineers were bridges and trestles. They were designed either as timber arches or timber trusses to reach spans of 20 m and up to 60 m. Illustrated in Figure 1 is the evolution of timber structure design over a period of about 250 year (years rounded to decade). Shown are the results of the great craftsmanship of Swiss carpenter Ulrich Grubenmann (Killer, 1998) using only sawn wood and few mechanical fasteners in 1756. The American Thompson S. Brown designed the RW Bridge about 100 years later utilizing structural analysis of arched trusses as it was available at that time by incorporating mechanical fasteners (Zimmer, 2002). Howard Hughes (Herzog et al, 2003) conquered yet another new challenge when put in charge of building an airplane, a task that would have been impossible to undertake without the use of adhesives. In modern day design of timber structures the computer has become an indispensable tool to allow   2 the completion of each task for complex structures such as the shell roof structure for the 2000 World Exposition EXPO in Hannover Germany (Herzog et al, 2003) (Herzog, 2000).  Figure 1: Development of wood design since 1750 With the industrial revolution and the technological developments in the second half of the 18th century came the mass production of iron and later, steel and concrete. The development of these materials and their ?superior? mechanical properties compared to wood almost led to the complete disappearance of wood as building material in commercial and high rise construction.  Only the limited availability of iron and steel after the Second World War and the targeted development in timber construction facilitated the revival of larger wood structures. Some key developments like that of glue laminated timber by Otto Hetzer (M?ller, 2000) at the beginning of the 20th century along with the development of connections and connectors further helped that revival.   3 It became apparent in recent years that the topic of connections in timber construction and design is a crucial one. Researchers around the world are targeting some inherent weaknesses of wood and moreover, connections in timber structures and revising current design rules and codes accordingly. These activities also led to the development of new connections and connection systems with superior structural properties. With these innovative connection systems, safer and more economical timber structures can be built since connection design is critical and often governing in timber engineering. Timber connections with dowel-type fasteners are typically designed based on the European-Yield model or Johansen theory (Johansen, 1949) and its ductile failure modes. Splitting failure becomes more and more severe due to the relatively low tension perpendicular to grain strength of the wooden connection members with an increase in the number of fasteners and the fastener diameter. Defects like cracks, specifically end-cracks in the wood, further reduce the resistance of a connection. Such cracks occur not only during drying and seasoning, but can also occur in glue laminated beams in indoor application during the service life of the beam. Furthermore, be it intended or non-intended by design, if moments were imposed onto the connection, splitting failure will occur. In the recent past more and more research is being conducted on the topic of reinforcement of such connections to increase their resistances and capacity. With the inherent low tension perpendicular to grain strength of wood and defects like cracks being a big concern for the splitting of connections, a lot of focus was set to reinforce dowel-type connections with the goal of minimizing splitting. The types of reinforcements are ranging from glued in rods over reinforcement with glued and   4 screwed on plywood and glued on high tensile fibres at the connection to more recently developed self-tapping wood screws (STS) with continuous threads. Figure 2 and Figure 3 show specimens that were reinforced using different types of high tensile fibres as well as a different method on applying the reinforcement. Although some reinforcement against splitting of the wood is provided, this method is used primarily to reinforce the embedment strength of the wood (Haller et al, 2006). The load displacement curve in Figure 4 shows the effectiveness of the reinforcement.  Figure 2: Knitted glass and aramid fibre fabric (spiral)  Figure 3: Transversally reinforced carbon fibre loop  Figure 4: Typical load-displacement curve   5 Madsen (2000) summarizes the research work done on glued-in steel rods and its broad applicability to multiple common problems in timber engineering. These applications reach from knee-joints, beam splices and moment connections to reinforcing the bearing strength as well as tension perpendicular to grain strength. An example of a beam splice using glued-in rods is shown in Figure 5. On the other hand Hockey (1999) and Bla? et al. (2000)  used commonly available and well know truss plates to reinforce bolted connections in both embedment strength as well as splitting perpendicular to the grain. Findings show an increase in ultimate capacity of the connection as well as a change in failure mode from brittle failure to a much more desirable ductile failure. The method of using truss plates as reinforcement offers an economical approach to the problem. First of all, the truss plates are comparably inexpensive as they are widely used in the manufacturing of conventional 2-by trusses. Another advantage of using truss plates is the fact that it eliminates the need for pre-drilled holes in the timber member, as they are required for glued in rods, but also is easier and cleaner to apply than fibre reinforces plastics that require epoxy resins for their application.   6  Figure 5: Beam splice using glued-in rods Self-tapping wood screws with continuous threads have also proven to not only to be an effective but also an economical method of reinforcing connections with dowel-type fasteners (Bejtka  Bla?, 2005). When compared to glued in rods and glued on fibre reinforcements for example, self-tapping wood screws are relatively inexpensive, fast and easy to install. The self-tapping wood screws, as their name implies, do not require any pre-drilling, similar to the afore mentioned truss plates, and can be installed virtually invisibly. This is another big advantage of such self-tapping wood screws especially when they are used in retrofit applications to restore and reinforce existing connections. However, the use of self-tapping wood screws is not limited to reinforcing connections,   7 but to generally reinforce inherent weaknesses of timber beams like the tension perpendicular to grain and compression perpendicular to grain strengths. 1.2. Self-tapping wood screws STSs provide economical means of assembling components, especially where materials must be joined together or reinforced. Thread forming and thread cutting are the two major types of self-tapping screws. The thread cutting screws remove the material physically from which they are drilled into and are typically used in timber connections. Thread forming STSs, however, plastically deform the material that they are driven into, providing a permanent thread. This distinguished mechanical and form giving bond with the wood, offers a great method of transferring tensile and compressive forces along the axis of the STS.  The development of STSs occurred primarily in Europe where earlier, more common, wood screws are widely used. These more common screws used the same principle of transferring loads, but were limited in dimensions. These types of wood screws are standardized according to DIN 96, DIN 97 or DIN 571 with a thread type in accordance with DIN 7998 for all of them. Screws with a thread type standardized in DIN 7998 require a pilot hole; their thread length makes up about 60% of the length of the screw with a length limited to about 150 mm. The limited length meant that these screws could not be used to connect members with larger cross-section. The commonly used lag-screws in North America are of similar nature and have essentially the same restrictions and a comparable thread type like the screws in accordance with DIN 7998 as shown in Figure 6.   8  Figure 6: Screw thread in accordance with DIN 7998 With the emergence of ever larger cross-sectional glue laminated timbers, the need for new longer screws was becoming more and more apparent. The development of self-tapping wood screws was filling that need with screw lengths of now up to 1,000 mm and diameters of up to 12 mm. STSs are manufactured as partially threaded screws and as screws with continuous thread depending on their application. A variety of different STSs are shown in Figure 7. To achieve such long, large diameter screws that can be installed without a pilot hole, the screws are hardened after the thread has been rolled onto them. The hardening of the screws is a highly secretive process; it is different for each manufacturer, which can increase the mechanical properties such as the yield strength, tensile and compressive strength, as well as the torsional strength of the screws. Self-tapping wood screws are manufactured with a drill-tip (Figure 8) and coated with a company specific lubricant to reduce the torque required to install the STS and to prevent splitting of the wood during installation. When partially threaded self-tapping wood screws are used, the introduction of a shank cutter as seen in Figure 9 helps to further reduce friction. Unlike the standardized conventional wood screws, self-tapping wood screws are not standardized and need a technical or general construction approval. In Germany the ?Deutsche Institut f?r Bautechnik? DIBt provides the technical approvals for non-standardized construction materials like STSs.   9  Figure 7: Self-tapping wood screws  Figure 8: Self-tapping wood screw drill-tips  Figure 9: Shank cutter on partially threaded screw The use of self-tapping screws, which eliminated the need for a pilot hole, has increased considerably over the past decade in Europe. Initially, a conceivably big disadvantage of self-tapping wood screws compared to nails, was the fact that little experimental work   10 had been done on these new types of screws. Most mechanical properties in wood-wood or wood-steel joints were estimated mainly by giving self-tapping screws the same properties as nails with similar dimensions. Therefore, the strongest attribute, the withdrawal resistance, of a self-tapping screw was not taken into account. In shear connections only their dowel action was taken into consideration during design. Furthermore, self-tapping screws could only be applied in timber connections without a pilot hole where the density of timber was less than 500-600 kg/m3 and if the shank diameter of the threaded part was less than 5-6 mm. Further research (Bla? & Bejtka, 2004) concerning lateral and withdrawal resistance of STSs in European species found that the lateral strength of self-tapping wood screws varied almost linearly with the specific gravity of the wood and the square root of the diameter of the screw. In addition, the withdrawal strength of self-tapping wood screws varies almost linearly with the embedment depth or, more specifically, the effective embedment length of the screw?s thread. No practical difference was observed between radial and tangential withdrawal strengths. In this study, basic strength data on the withdrawal capacity of self-tapping screws with major Canadian wood species is evaluated. This basic information is needed for the development of design rules for these types of screws with Canadian species. The establishment of such design rules would allow engineers and builders to facilitate the full potential of these types of screws. This is of great interest to engineers in North America as they are facing similar technical issues as their European colleagues in that right now STSs can only be designed as lag-screws or nails. As previously mentioned, using the lag-screw or nail equivalent approach; the greatest benefit of the self-tapping   11 screws, the high withdrawal capacity, is entirely neglected. By establishing evaluation data the full benefit of the screws could be explored.  The use of STSs is vast and many different kinds of applications have been tried and looked at by researchers (Bla? & Bejtka, 2004). In Europe these screws are used as reinforcements for longitudinal shear, tension perpendicular to the grain, and compression perpendicular to the grain. They are also used to reinforce embedment strength in dowel-type connections and, more recently, have been discovered as primary fasteners as well. The application as reinforcements is wide-spread and ranges from rehabilitation of old existing structures and members to reinforcement for connections, as shown in Figure 10.  Figure 10: STS as embedment and splitting reinforcement  Research done by Lam et al. (2008) at the University of British Columbia (UBC) investigated the use of STS in moment resisting bolted connections as reinforcement   12 perpendicular to the grain. The study compared results of unreinforced specimens to specimens that were previously broken and rehabilitated using STS as well as specimens that were reinforced using self-tapping wood screws. The results revealed that the ultimate capacity as well as ductility of the connections could be improved using STS as reinforcement. It is worth noting that even the previously broken specimens that were rehabilitated using STS had significantly higher values of capacity than the unreinforced specimens. Additional work done by Lam et al. (2010) and Gehloff et al. (2010) at UBC looked at further increasing the capacity of such moment resisting bolted connections by using larger diameter bolts with reduced end and edge distances. The results confirmed that the reinforcement with self-tapping wood screws is a viable method to increase the capacity and ductility of bolted connections subjected to cyclic loading; even for connections with larger diameter bolts, which are more prone to splitting, and reduced end and edge distances.   13 2.  EXPERIMENTAL DESIGN / EQUATIONS 2.1. Parameter considerations The focus of this work is the pull out resistance or withdrawal resistance of self-tapping screws with continuous thread. Experiments are conducted by testing the pull out resistance at different angles to the grain in different wood species. The angles of the screw to the grain are 90 degrees (perpendicular), 45 degrees and 30 degrees. The pull out resistance will be compared under the afore mentioned angles and different embedment depths in three different wood species. The chosen wood species are Douglas-fir and S-P-F glulam, as well as, Hemlock solid sawn timber to cover the most commonly used construction materials in Canadian heavy timber construction and density range. The screws used for the tests are W?rth ASSY plus VG?, where VG denotes continuous thread. The W?rth ASSY plus VG? screws are of 6 mm, 8 mm and 10 mm in diameter and are provided in various lengths of up to 800 mm for the 10 mm diameter screws. Preliminary withdrawal tests were conducted by pulling the screws from the specimens. Results have shown that the tensile strength of the screw itself became the limiting factor at embedment depths of ~12d (d = diameter of the screw). The test setup was                 re-configured in a way that instead of pulling on the screws, the screws were pushed into the wood. Preliminary tests also revealed that the heads of the screws failed at the shoulder between the shaft of the screw and the head when the screws were tested by pulling them through the specimen. This stress concentration resulted from the grip device of the test setup which would not be present in real applications. When the screws   14 are used with steel side plates, the screws have to be counter-sunk into the steel plates to ensure proper contact of the screw head and shoulder with the steel plate to avoid stress concentrations and premature failure. Further preliminary tests proved that the new compression based setup was more suitable to get results at higher embedment depths of up to 16d before the screws failed in buckling. Based on these preliminary results, four different embedment depths were selected: 4d, 10d, 12d and 16d. The low embedment depth of 4d was selected to gather insights on the reinforcement of bolted connection with smaller edge distances.  For each combination of screw diameter, embedment depth, angle to the grain and wood species, 10 replications were tested. With 108 different setups and 10 replicates for each setup, a total of 1080 test were conducted and evaluated. Furthermore, the results are compared to predictions based on the German building code DIN 1052:2004-8 and the Eurocode 5. Both building codes predict the withdrawal resistance of this type of screws and therefore their potential as reinforcement in tension perpendicular to grain in dowel-type connections. Input parameters in the equations in the German code are the mean specific gravity of the wood, the angle to the grain, the screw diameter and the embedment depth. These parameters coincide with the studied parameters in the tests conducted for this study.      15 2.2. Test setup The machine used for the tests was the Sintech 30/D with a 1,500 kN load cell. Wooden blocks were used to create enough clearance above the machine test table for the screws. Steel rectangular tubing was used to reduce the span and therefore limit the deflection of the specimens. A transducer was used to measure the wood deflection near the tested screw as correction value. Figures 11to13 show the test setup for the 90, 45 and 30 degree tests respectively. The transducer used to measure the deflection of the specimen is shown in Figure 14.   Figure 11: Test setup for 90? tests   16  Figure 12: Test setup for 45? tests  Figure 13: Test setup for 30? tests   17  Figure 14: Transducer to measure deflection As shown in Figures 11 to 13, the screws were driven all the way through the specimen to eliminate any resistance at the screw tip during testing, as well as to reduce the slenderness ratio. The reduced slenderness will help prevent buckling of the screws at higher loads and greater embedment depths. The embedment depth was controlled by the thickness of the specimens. All specimens were cut and planed to the thickness that equalled the embedment depth for the specific tests. Table 1 and Figure 15 show the effective embedment depth for the different screw inclinations. The embedment depths were chosen to remain constant since, otherwise, not enough material would have been left to properly install the screws and test the screws without breaking the wood first. In a situation where the screws are used to reinforce bolted connections the approach would be similar. The calculated minimum edge distances, even if reduced due to the presence of self-tapping wood screws as reinforcement for the bolts would, be a value that is   18 perpendicular (90?) to the edges of the beam. Thus, the obtained withdrawal resistance values are applicable to such reinforcements even if it means that the values for different screw inclinations cannot be compared directly. Table 1: Effective embedment depths   Figure 15: Effective embedment depth Embedment depth Effective embedment depth 90? 45? 30? 4d 4d (1/sin 45?) 4d (1/sin 30?) 4d ~ 5.656 d 8 d 10d 10d (1/sin 45?) 10d (1/sin 30?) 10d ~ 14.142 d 20 d 12d 12d (1/sin 45?) 12d (1/sin 30?) 12d ~ 16.968 d 24 d 16d 16d (1/sin 45?) 16d (1/sin 30?) 16d ~ 22.624 d 32 d   19 To transfer the load from the load cell to the head of the self-tapping screw, a harden hex-head screw was used. Due to the hardness of the self-tapping screw the hex-head was introduced to avoid damage to the load cell.  Testing was done in accordance with the German standard DIN EN 1832, which specifies the speed of testing such that failure can be reached in 90 seconds ? 30 seconds. Multiple screws were placed in the specimens to speed up testing. The row spacing of ? 5d as well as the end, edge and screw spacing of ? 10d was followed as given in the standard.   2.3. European code equations The German wood building code DIN 1052:2004-08 defines the withdrawal resistance of screws by taking the tensile strength min. fu,k = 400 N/mm2 of the screw, the axial capacity of the thread in wood and the head-pull through into account. Given that, head pull through of full threaded screws is neglected, the main parameters influencing withdrawal resistance are the penetration depth of the thread (lef) including the tip embedded in the wood, the diameter (d), the angle (?) and the characteristic value of the withdrawal resistance (Kf .1 ). Further influencing parameters are the apparent density, as well as the axial capacity of the threaded part embedded in the wood. Wood screws are separated into three different strength groups regarding their characteristic axial capacity parameter (Kf .1 ). For group one to three, the parameter is 26,1 10 kKf ?????  where the value (? ) can vary from 60 for group one, 70 for group two and 80 for group three, respectively. Group one represents any wood screw other than screws that can be placed into either of the other two groups. Screws with threads in accordance with DIN 7998   20 (Figure 6) can be placed in group two without the need of further proof. Group three, on the other hand, represents a group for hardened screws that are proven to withstand a certain threshold capacity and generally require a general construction approval.  Self-tapping wood screws require a general construction approval and fall into group three unless stated otherwise in the approval of the particular screw. The characteristic value of the withdrawal resistance kaxR ,  is calculated by Equation 1. ???????????????? 2.222.1. ;cos34sinmin kKefKKax dfldfR??[N]  (1) where; 26,1 10 kKf ?????  , with  ?k = characteristic density, kg/m3 d = outside screw diameter, mm lef = effective embedment depth including the tip, mm ? = angle between screw length axis and wood grain, degree (?) The second part of Equation 1 is used to calculate the head pull-through resistance of the screws, where Kf .2  denotes the characteristic head pull-through parameter and kd the outside head diameter, or if a washer is used the outside diameter of the washer. In case of fully threaded self-tapping wood screws, however, the head pull-through resistance is not considered since the loads are transferred through the thread and the shaft of the screws and not the head.    21 Equation 1 can only be applied for angles 45?? ? ?90?. Bla? and Bejtka (2004) show that the equation holds true for angles (?) down to 30?. In addition, Bla? et al. (2006) found that the predicted withdrawal resistance kaxR ,  is very conservative. Thus, the characteristic axial capacity Kf .1 could be increased by increasing the value (? ) up to 113 for 90? angles and up to 109 for angles less than 90?. Contrary to the value of kaxR ,  presented in DIN 1052:2004-08 where the screw tip is included in the effective embedment depth of the thread in the wood, Equation (2) of the Eurocode (EC) 5-2004 considers the screw tip by subtracting one time the diameter (d) from the embedded length. Furthermore, a possible group effect is taken into consideration by an exponent for the number of fasteners (n).  ? ? ?? ?? 225.138.09.0. cos5.1sin106.3?????????kefKax ldnR  [N]  (2) where; d = outside screw diameter, mm lef = effective embedment depth excluding the tip, mm ?k = characteristic density, kg/m3 ? = angle between screw length axis and wood grain, degree (?) The findings by Bla? and Bejtka (2003) show Equation 2 over-predicted the withdrawal resistance kaxR ,  compared to their test results and, in conclusion, the parameter of 3.6 was lowered to 2.85 to match the test results.    22 2.4. Equivalency calculations Neither the Canadian timber building code CSA-O86-09, nor the National Design Specifications (NDS) in the United States give indication for the calculation of the withdrawal resistance of wood screws similar to the self-tapping wood screws. As no technical approvals are in existence to date in North America for this type of screw, only equivalency calculations can be done. The only dowel type fasteners that are of similar type and are permitted to be loaded axial in withdrawal are nails and spikes, wood screws and lag-bolts or lag-screws.  When looking at the Canadian CSA-O86-09, paragraph 10.9.5.1 states that nails and spikes may only be loaded in withdrawal for wind and earthquake design. The same is stated for wood screws in paragraph 10.11.5.1. Consequently, an equivalency calculation is only given for wood screws as they have more similarity to self-tapping wood screws than nails and spikes. The only fastener permitted to be designed in withdrawal in accordance with CSA-O86-09 that is similar in shape and function to the self-tapping wood screw is the lag-bolt or lag-screw. The NDS in the United States, however, permits the axial loading in withdrawal for all three types of fasteners, the nail and spike, wood screw as well as the lag-bolt or lag-screw; both terms are used interchangeably. The withdrawal resistance of lag-bolts in accordance with the Canadian CSA-O86-09 is calculated with Equation 3 and CSA-O86-09 Table 10.6.5.1 as follows; eFtwrw JnLYP ????? ?   [N/mm]  (3)   23 where; ? = 0.6 Yw = yw (KDKSFKT) yw = basic withdrawal resistance per millimeter of penetration, N/mm (Table 10.6.5.1) Lt = length of penetration of threaded portion of lag-bolt in main member, mm nF = number of lag-bolts in the connection Je = end grain factor for lag-bolts; 0.75 in end grain, 1.00 in all other cases For wooden side members an appropriate washer has to be used to prevent the head of the lag-bolt from pulling through the side member. The withdrawal resistance of wood-screws in accordance with the Canadian CSA-O86-09 is calculated with Equation 4 and CSA-O86-09 Tables A.10.1 and 10.11.1 as follows; Ftpwrw nLYP ???? ?  [N/mm] (4) where; ? = 0.6 Yw = yw (KTKSF) yw = basic withdrawal resistance per millimeter of threaded shank penetration in main member; = 68 dF0.82 G1.77 , N/mm G = mean relative density of main member (Table A.10.1) df = nominal wood screw diameter, mm (Table 10.11.1) Lpt = threaded length penetration in the main member, mm nF = number of wood screws in the connection For a joint with three members, the threaded length penetration shall be the maximum   24 threaded length within any member other than the head-side member. For wooden side members an appropriate washer has to be used to prevent the head of the wood screw from pulling through the side member. In accordance with the United States NDS, the withdrawal resistance is calculated by multiplying the reference withdrawal resistance W with all applicable adjustment factors as they can be found in Table 10.3.1 in the NDS. The reference withdrawal resistance is calculated with Equations 5 to 7 for lag-bolts, wood screws and nails and spikes respectively. These values are also tabulated in NDS Tables 11.2A, 11.2B and 11.2C respectively. 4/32/31800 DGW ???    [lb/in]  (5) DGW ??? 22850  [lb/in]  (6) DGW ??? 2/51380    [lb/in]  (7) The calculations for the withdrawal resistance in Canada as well as the United States are limited to the fastener being installed perpendicular to the grain, meaning an angle of 90? between the axis of the screw and the grain. No other installation angles are allowed; thus limiting design parameters to the diameter of the fastener, the penetration depth of the fastener, and the density of the wood member the fastener is driven into. A comparison of the calculated withdrawal resistances using the DIN and Eurocode code equations as well as the equivalency calculations is given in Chapter three. The results of various calculated predictions are also compared to the test results in an effort to evaluate their respective applicability.    25 3. RESULTS / DISCUSSION 3.1. Results  The withdrawal test results are shown in Table 3 through Table 5 for all 108 test series. Each test configuration was tested with 10 replicates bringing the total number of tests to 1080 individual screws. The tables are formatted to group the results for all screws with the same angle between the axis of the screw relative to the grain. It should be mentioned that the results in Tables 3 to 5 showing average values for the 6 mm, 8 mm and 10 mm screws respectively, are taken from all 10 test replicates and are not calculated based on the shown minimum and maximum values alone. To display the results a little more clearly and to be able to understand the effects of different parameters, the results are also shown in Figures 16 to 24. The figures are divided not only into the angle of screw installation with respect to the grain, but also split into single screw diameters in order to keep the graphs legible. The error bars show the minimum and maximum test values. The data below clearly shows the effect the individual parameters have on the results. With an increase in embedment depth, the withdrawal resistance also increased. The same can be said for the increase in screw diameter and the different densities of the wood samples. The effect of the density, however, can only really be discussed on the bases of the different wood species (Table 2) as multiple screws were tested in the same specimen and local density variations like knots within the specimen were present.  Table 2: Average densities  Douglas-fir Spruce - Pine - Fir Hemlock Average density [kg/m3] 530.58 463.89 512.88 Standard Deviation [kg/m3] 37.20 34.78 38.164   26 Table 3: Withdrawal test results for 90?  Test configuration Withdrawal Capacity [kN] ? [mm] Embedment Angle [?] Species Min Max Average STDV 6 4d 90 DF 2.709 4.510 3.508 0.570 6 4d 90 SPF 2.357 4.270 3.195 0.658 6 4d 90 H 2.487 3.478 2.926 0.371 6 10d 90 DF 9.456 18.070 13.285 3.094 6 10d 90 SPF 7.216 8.152 7.725 0.320 6 10d 90 H 10.793 18.304 13.426 2.251 6 12d 90 DF 11.441 16.700 14.180 1.779 6 12d 90 SPF 8.846 10.698 9.627 0.699 6 12d 90 H 13.396 18.383 15.859 2.070 6 16d 90 DF 15.599 18.071 16.884 0.790 6 16d 90 SPF 13.904 16.308 14.890 0.829 6 16d 90 H 14.389 15.869 15.111 0.543 8 4d 90 DF 6.024 9.200 7.160 0.852 8 4d 90 SPF 4.427 5.779 5.058 0.475 8 4d 90 H 3.944 8.027 4.892 1.193 8 10d 90 DF 14.817 19.218 17.284 1.502 8 10d 90 SPF 12.062 13.765 12.751 0.555 8 10d 90 H 13.042 16.842 15.324 1.131 8 12d 90 DF 18.162 25.547 22.136 2.541 8 12d 90 SPF 16.460 20.857 18.255 1.295 8 12d 90 H 14.172 26.745 19.228 3.826 8 16d 90 DF 23.607 27.561 25.889 1.228 8 16d 90 SPF 20.746 26.298 23.420 2.162 8 16d 90 H 21.741 28.413 24.396 2.651 10 4d 90 DF 6.819 9.331 8.150 0.905 10 4d 90 SPF 6.263 7.215 6.921 0.299 10 4d 90 H 6.892 9.923 8.017 0.830 10 10d 90 DF 22.783 30.383 27.904 2.126 10 10d 90 SPF 15.343 21.701 19.237 1.955 10 10d 90 H 14.123 20.906 18.485 2.984 10 12d 90 DF 25.489 38.549 33.235 5.460 10 12d 90 SPF 22.654 27.909 25.529 1.628 10 12d 90 H 19.867 38.995 29.353 6.608 10 16d 90 DF 32.237 37.842 35.948 1.726 10 16d 90 SPF 25.158 31.425 28.956 2.120 10 16d 90 H 25.264 36.096 29.615 4.043 Note: DF = Douglas-fir, SPF = Spruce-Pine-Fir, H = Hemlock   27  Figure 16: Average withdrawal resistance for 6 mm screw @ 90?   Figure 17: Average withdrawal resistance for 8 mm screw @ 90?  0.002.004.006.008.0010.0012.0014.0016.0018.0020.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 6 mm @ 90? angle Douglas-firS-P-FHem.-fir0.005.0010.0015.0020.0025.0030.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 8 mm @ 90? angle Douglas-firS-P-FHem.-fir  28  Figure 18: Average withdrawal resistance for 10 mm screw @ 90?  Results shown in Figures 16 to 18 indicate a general trend that the average values for the withdrawal resistance following the same trend as the average densities. With an increased average density, the values for the average withdrawal resistance are also increased. The above stated effect of the embedment depth as well as the screw diameter is also clearly seen in the graphs.  The permissible characteristic tensile strength of the screws as per the German general construction approval are 11.3 kN for the 6 mm screws, 18.9 kN for the 8 mm screws and 24.0 kN for the 10 mm screws. Granted the fact that the permissible characteristic values for the tensile strength of the steel are 5th percentile value and the shown withdrawal values are average values, it can still be seen that the embedment depth of 16d almost always cause the screw to fail not the wood in withdrawal. A closer look at this will be taken in the discussions section of this study.  0.005.0010.0015.0020.0025.0030.0035.0040.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 10 mm @ 90? angle Douglas-firS-P-FHem.-fir  29 Table 4: Withdrawal test results for 45?  Test configuration Withdrawal Capacity [kN] ? [mm] Embedment Angle [?] Species Min Max Average STDV 6 4d 45 DF 3.978 4.729 4.313 0.243 6 4d 45 SPF 2.370 3.163 2.929 0.223 6 4d 45 H 2.627 6.000 3.278 1.007 6 10d 45 DF 12.447 14.115 13.090 0.553 6 10d 45 SPF 10.559 14.018 11.882 1.131 6 10d 45 H 13.575 15.998 14.419 0.887 6 12d 45 DF 14.111 16.428 15.039 0.654 6 12d 45 SPF 12.492 15.715 13.985 0.915 6 12d 45 H 13.881 15.534 14.701 0.513 6 16d 45 DF 13.347 16.264 15.306 0.831 6 16d 45 SPF 13.915 15.483 14.849 0.487 6 16d 45 H 12.941 16.143 14.635 0.792 8 4d 45 DF 3.494 6.494 5.686 0.947 8 4d 45 SPF 5.727 6.407 6.041 0.218 8 4d 45 H 3.938 7.151 5.177 1.157 8 10d 45 DF 22.388 25.738 23.740 1.071 8 10d 45 SPF 16.722 22.843 19.354 1.859 8 10d 45 H 15.680 23.638 19.864 2.958 8 12d 45 DF 19.805 24.611 22.844 1.549 8 12d 45 SPF 21.311 23.327 22.310 0.559 8 12d 45 H 20.299 23.057 21.760 0.821 8 16d 45 DF 19.942 24.062 21.902 1.130 8 16d 45 SPF 19.811 24.916 21.805 1.474 8 16d 45 H 18.018 23.052 20.833 1.622 10 4d 45 DF 5.795 9.590 7.921 1.260 10 4d 45 SPF 7.012 8.762 7.897 0.624 10 4d 45 H 3.281 12.477 8.563 3.432 10 10d 45 DF 24.315 31.525 29.074 2.107 10 10d 45 SPF 22.840 30.619 27.473 1.988 10 10d 45 H 23.657 30.682 27.798 2.310 10 12d 45 DF 26.833 32.862 30.214 1.730 10 12d 45 SPF 24.673 33.323 29.104 2.463 10 12d 45 H 28.547 33.579 31.241 1.759 10 16d 45 DF 25.259 32.731 29.418 2.124 10 16d 45 SPF 24.369 32.343 28.883 2.180 10 16d 45 H 26.062 32.916 30.086 2.571 Note: DF = Douglas-fir, SPF = Spruce-Pine-Fir, H = Hemlock   30  Figure 19: Average withdrawal resistance for 6 mm screw @ 45?   Figure 20: Average withdrawal resistance for 8 mm screw @ 45? 0.002.004.006.008.0010.0012.0014.0016.0018.0020.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 6 mm @ 45? angle Douglas-firS-P-FHem.-fir0.005.0010.0015.0020.0025.0030.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 8 mm @ 45? angle Douglas-firS-P-FHem.-fir  31  Figure 21: Average withdrawal resistance for 10 mm screw @ 45?  The values for inclination angles of 45?, as well as 30?, are exhibiting similar trends as seen for the perpendicular to the grain installed screws. However, the effect of the increased effective embedment depth leads to screw failure in a few cases at a depth of 10d since the effective depth would be about 14d compared to the 90 degree tests (Table 1). This is even more apparent for angles of 30 degrees where almost all specimens at 10d already shown steel failure in the screw instead of withdrawal failure in the wood.  The calculated embedment depth for perpendicular installed screws would be in the range of 12d to 14d depending on the density of the wood. Figure 25 depicts typical screw failure as it is reached when the embedment depth exceeds the limit the steel of the screw can transfer into the wood. Figure 26 shows a typical load displacement plot of the withdrawal test, all plots can be found in the appendix.  0.005.0010.0015.0020.0025.0030.0035.0040.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 10 mm @ 45? angle Douglas-firS-P-FHem.-fir  32 Table 5: Withdrawal test results for 30? Test configuration Withdrawal Capacity [kN] ? [mm] Embedment Angle [?] Species Min Max Average STDV 6 4d 30 DF 4.618 7.090 5.893 0.851 6 4d 30 SPF 3.672 6.179 4.430 0.755 6 4d 30 H 4.598 8.079 6.100 1.061 6 10d 30 DF 13.615 15.312 14.511 0.489 6 10d 30 SPF 11.435 14.556 13.087 1.187 6 10d 30 H 13.624 14.519 14.124 0.282 6 12d 30 DF 13.036 15.181 14.179 0.793 6 12d 30 SPF 13.108 14.899 13.978 0.668 6 12d 30 H 12.379 14.568 13.908 0.627 6 16d 30 DF 13.328 14.904 14.059 0.471 6 16d 30 SPF 11.735 14.543 13.517 0.867 6 16d 30 H 13.879 15.175 14.605 0.449 8 4d 30 DF 9.994 16.214 12.789 1.884 8 4d 30 SPF 6.559 13.664 8.522 2.061 8 4d 30 H 8.822 13.466 10.443 2.216 8 10d 30 DF 19.691 23.128 21.451 1.113 8 10d 30 SPF 19.816 24.581 22.273 1.428 8 10d 30 H 19.108 24.780 21.110 1.540 8 12d 30 DF 22.047 26.307 23.875 1.147 8 12d 30 SPF 21.678 24.163 22.679 0.827 8 12d 30 H 19.762 22.221 21.339 1.046 8 16d 30 DF 21.153 23.549 22.201 0.931 8 16d 30 SPF 20.192 22.922 21.526 0.950 8 16d 30 H 17.609 22.266 20.132 1.407 10 4d 30 DF 17.485 20.391 19.083 1.021 10 4d 30 SPF 11.044 17.409 15.224 1.782 10 4d 30 H 12.454 21.633 16.258 3.102 10 10d 30 DF 29.572 34.166 31.217 1.434 10 10d 30 SPF 27.677 31.918 29.731 1.203 10 10d 30 H 25.441 31.039 29.363 1.853 10 12d 30 DF 28.549 31.746 30.727 1.103 10 12d 30 SPF 29.787 33.906 31.389 1.141 10 12d 30 H 26.334 33.890 29.618 2.642 10 16d 30 DF 29.229 35.660 31.540 1.794 10 16d 30 SPF 28.602 32.158 29.936 0.953 10 16d 30 H 19.810 30.257 26.675 3.000 Note: DF = Douglas-fir, SPF = Spruce-Pine-Fir, H = Hemlock   33  Figure 22: Average withdrawal resistance for 6 mm screw @ 30?   Figure 23: Average withdrawal resistance for 8 mm screw @ 30? 0.002.004.006.008.0010.0012.0014.0016.0018.0020.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 6 mm @ 30? angle Douglas-firS-P-FHem.-fir0.005.0010.0015.0020.0025.0030.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 8 mm @ 30? angle Douglas-firS-P-FHem.-fir  34  Figure 24: Average withdrawal resistance for 10 mm screw @ 30?   Figure 25: Typical screw failure 0.005.0010.0015.0020.0025.0030.0035.0040.004d 10d 12d 16dAvarege withdrawal resistance [kN] Embedment depth W?rth 10 mm @ 30? angle Douglas-firS-P-FHem.-fir  35  Figure 26: Typical load deformation plot  The densities and moisture content for all specimens have been recorded during the testing.  A needle moisture meter was used to measure the moisture content, driving the needles about 25 mm in to the specimen. The moisture content varied from 7.25% to 13.00% with most specimens having moisture contents between 8.00% and 10.00%. To establish the density of the specimens, the specimens were weighed at the ambient climate and their respective moisture contents and measured in all dimensions to establish their volume. The density was then calculated using the measured weight and volume of the specimens. Densities for all specimens, regardless of species, have been sorted in density groups with 20 kg/m3 increments and a normal distribution has then been fitted, as shown in Figure 27.  Figure 27 shows that a normal distribution fits quite well to the recorded density values. 0246810120 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  12d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  36   Figure 27: Wood density distribution  3.2. Discussion In Table 6, calculated characteristic values are compared to the minimum value of the test, in lieu of the 5th percentile value, due to the low number of test replicates. The results in general confirm the findings by Bla? and Bejtka (2004). In most cases the German DIN 1052:2004-8 (Equation 1) seems to produce conservative results for 90?, especially for higher embedment depths. It is also confirmed that the Equation 2 used in the EC 5 over-predicts the withdrawal resistance in most cases. Neither the US code nor the Canadian code allow for the calculation of withdrawal capacities at an angle other than 90?. Thus, the comparisons shown in Table 6 were chosen for an angle to the grain of 90?. The densities used in the calculations are taken from the averages measured during the tests as shown in Table 2.  00.0020.0040.0060.0080.010.012380 430 480 530 5800%2%4%6%8%10%12%14%16%18%20%22%24%26%28%400 420 440 460 480 500 520 540 560 580 600 620Relative frequency [%] Density [kg/m3] Wood density distribution   37 Table 6: Comparison of test results to code equation predictions for STS Code predictions @ 90? Withdrawal Capacity [kN] ?  [mm] Embed. Depth Species (G) Min. Test DIN EC5 CSA lag CSA screw NDS lag NDS screw NDS nail 6 4d 24 DF 0.53 4.51 3.24 5.85 1.78 2.92 1.03 0.84 0.30 4d 24 SPF 0.46 2.36 2.44 4.73 0.74 2.27 0.83 0.63 0.21 4d 24 H 0.51 2.49 3.00 5.52 0.89 2.73 0.97 0.78 0.27 10d 60 DF 0.53 9.46 8.09 12.18 4.44 7.30 2.58 2.10 0.74 10d 60 SPF 0.46 7.22 6.09 9.84 1.86 5.68 2.09 1.58 0.52 10d 60 H 0.51 10.79 7.49 11.49 2.22 6.82 2.44 1.95 0.67 12d 72 DF 0.53 11.44 9.71 14.09 5.33 8.76 3.10 2.52 0.89 12d 72 SPF 0.46 8.85 7.31 11.39 2.23 6.81 2.50 1.90 0.62 12d 72 H 0.51 13.40 8.99 13.30 2.66 8.18 2.92 2.34 0.81 16d 96 DF 0.53 15.60 12.94 17.73 7.10 11.68 4.13 3.36 1.19 16d 96 SPF 0.46 13.90 9.75 14.34 2.98 9.09 3.34 2.53 0.83 16d 96 H 0.51 14.39 11.99 16.74 3.55 10.91 3.90 3.12 1.08 8 4d 32 DF 0.53 6.02 5.75 9.27 3.10 3.89 1.63 1.40 0.49 4d 32 SPF 0.46 4.43 4.33 7.49 1.34 3.03 1.32 1.06 0.35 4d 32 H 0.51 3.94 5.33 8.75 1.76 3.64 1.54 1.30 0.45 10d 80 DF 0.53 14.82 14.38 19.29 7.76 9.73 4.07 3.51 1.24 10d 80 SPF 0.46 12.06 10.83 15.60 3.36 7.57 3.29 2.64 0.87 10d 80 H 0.51 13.04 13.32 18.21 4.40 9.09 3.84 3.25 1.12 12d 96 DF 0.53 18.16 17.26 22.32 9.31 11.68 4.88 4.21 1.48 12d 96 SPF 0.46 16.46 13.00 18.05 4.03 9.09 3.95 3.17 1.04 12d 96 H 0.51 14.17 15.98 21.07 5.28 10.91 4.61 3.89 1.35 16d 128 DF 0.53 23.61 23.01 28.10 12.42 15.57 6.51 5.61 1.98 16d 128 SPF 0.46 20.75 17.33 22.72 5.38 12.12 5.26 4.22 1.39 16d 128 H 0.51 21.74 21.31 26.52 7.04 14.54 6.14 5.19 1.80 10 4d 40 DF 0.53 9.33 8.99 13.25 4.80 4.86 2.33 2.10 0.74 4d 40 SPF 0.46 6.26 6.77 10.71 2.44 3.79 1.89 1.58 0.52 4d 40 H 0.51 6.89 8.32 12.50 2.80 4.54 2.20 1.95 0.67 10d 100 DF 0.53 22.78 22.47 27.57 12.00 12.16 5.83 5.26 1.85 10d 100 SPF 0.46 15.34 16.93 22.29 6.10 9.47 4.71 3.96 1.30 10d 100 H 0.51 14.12 20.81 26.02 7.00 11.36 5.50 4.87 1.68 12d 120 DF 0.53 25.49 26.97 31.90 14.40 14.59 6.99 6.31 2.22 12d 120 SPF 0.46 22.65 20.31 25.79 7.32 11.36 5.66 4.75 1.56 12d 120 H 0.51 19.87 24.97 30.11 8.40 13.63 6.60 5.84 2.02 16d 160 DF 0.53 32.24 35.96 40.15 19.20 19.46 9.33 8.41 2.97 16d 160 SPF 0.46 25.16 27.08 32.47 9.76 15.14 7.54 6.34 2.08 16d 160 H 0.51 25.26 33.29 37.90 11.20 18.18 8.80 7.79 2.69 Note: DF = Douglas-fir, SPF = Spruce-Pine-Fir, H = Hemlock    * ** ** ** ** *** *** * of 10 tests; ** characteristic value (5th percentile); *** allowable stress design value ***   38 Using the CSA O86-09 wood screw withdrawal resistance equivalent (Equation 4) gives the closest values of any of the equivalent methods, but still significantly under-predicts the test results. The screw diameter and angle to the grain are considered in Figures 28 to 45, which show the relationship between DIN and EC5 predicted characteristic withdrawal resistance compared to test results. The figures show the withdrawal capacities calculated using the respective code equations of DIN and EC5, which for larger embedment depth is higher than the tensile strength of the screw itself. The tensile strength of the screws are shown in the figures as dotted lines, meaning values that are beyond that line would be governed by the screws tensile strength rather than the withdrawal capacity from the wood. Thus, the values in the lower left part of the graph are the pivotal ones and considered in the discussions below. The results show trends that could generally confirm the work done by Bla? and Bejtka (2004). The design equation given in the German DIN (Equation 1) are valid for wood of densities up to 500 kg/m3 and should be carefully checked for applicability to North American species, especially at higher densities. On the other hand, the EC5 design equation does not specify a limit in density. When looking at the figures for the comparison to EC5 (Figures 29 to 45) it shows that the EC5 equation over-predicts the withdrawal capacities especially when compared to the minimum test values as mentioned before. The equation according to DIN also over-predicts for the 4d embedment depths and even more for other depths for screw diameters of 8 mm and 10 mm. For withdrawal values at angles other than 90? the tensile strength of the screw becomes limiting in most cases due to the increased effective embedment depths.    39  Figure 28: Comparison of 6 mm results with DIN 1052:2004-8 predictions @ 90?   Figure 29: Comparison of 6 mm results with EC 5 predictions @ 90? 0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 6 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 6 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  40  Figure 30: Comparison of 6 mm results with DIN 1052:2004-8 predictions @ 45?   Figure 31: Comparison of 6 mm results with EC 5 predictions @ 45? 0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 6 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 6 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  41  Figure 32: Comparison of 6 mm results with DIN 1052:2004-8 predictions @ 30?   Figure 33: Comparison of 6 mm results with EC 5 predictions @ 30? 0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 6 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 6 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  42  Figure 34: Comparison of 8 mm results with DIN 1052:2004-8 predictions @ 90?   Figure 35: Comparison of 8 mm results with EC 5 predictions @ 90? 05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 8 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 8 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  43  Figure 36: Comparison of 8 mm results with DIN 1052:2004-8 predictions @ 45?   Figure 37: Comparison of 8 mm results with EC 5 predictions @ 45? 05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 8 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 8 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  44  Figure 38: Comparison of 8 mm results with DIN 1052:2004-8 predictions @ 30?   Figure 39: Comparison of 8 mm results with EC 5 predictions @ 30? 05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 8 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 8 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  45  Figure 40: Comparison of 10 mm results with DIN 1052:2004-8 predictions @ 90?   Figure 41: Comparison of 10 mm results with EC 5 predictions @ 90? 051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 10 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 10 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  46  Figure 42: Comparison of 10 mm results with DIN 1052:2004-8 predictions @ 45?   Figure 43: Comparison of 10 mm results with EC 5 predictions @ 45? 051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 10 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 10 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  47  Figure 44: Comparison of 10 mm results with DIN 1052:2004-8 predictions @ 30?   Figure 45: Comparison of 10 mm results with EC 5 predictions @ 30? 051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Predicted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 10 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Predicted withdrawal resistance Eurocode 5 [kN] W?rth 10 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  48 Results of the study by Bla? et al. (2006) suggested adjustments to Equation 1. Changing the characteristic axial capacity Kf .1  by increasing the values of ?  to 109 are shown in Figures 46 to 62. The comparisons of the calculations to the observed test values are un-conservatively over-predicted and undesirable. The values of ? should actually be slightly reduced for major Canadian species, although a larger number of tests than done in this study are required to make more definitive statements. In case of the by Bla? and Bejtka (2004) suggested adjustment to Eurocode 5 (Equation 2), the parameter of 3.6 was lowered to 2.85 to better match the test results and avoid over-predicting the withdrawal resistance. Figures 47 to 63 show that the adjusted EC5 equation predicts more conservatively than the unadjusted equation, especially at higher embedment depths. For embedment depths of 4d the adjusted EC5 equation still over-predicts the withdrawal capacity, but the results are closer to the observed test results as they were when using the current, uncorrected EC5 equation. However, neither adjustment properly predicts the results of the tests and needs to be revisited. For major Canadian species the equations need to be further optimized, but more test data is required to do so effectively and accurately. Another observation is that starting at an embedment depth of about 10d to 12d, depending on the screw angle, the tensile capacity (as per German General Construction Approval) of the W?rth ASSY plus VG screw is reached.    49  Figure 46: Comparison of 6 mm results with DIN 1052:2004-8 adjustments @ 90?   Figure 47: Comparison of 6 mm results with EC 5 adjustments @ 90? 0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 6 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 6 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  50  Figure 48: Comparison of 6 mm results with DIN 1052:2004-8 adjustments @ 45?   Figure 49: Comparison of 6 mm results with EC 5 adjustments @ 45? 0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 6 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 6 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  51  Figure 50: Comparison of 6 mm results with DIN 1052:2004-8 adjustments @ 30?   Figure 51: Comparison of 6 mm results with EC 5 adjustments @ 30? 0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 6 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity0246810121416182022242628300 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 6 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  52  Figure 52: Comparison of 8 mm results with DIN 1052:2004-8 adjustments @ 90?   Figure 53: Comparison of 8 mm results with EC 5 adjustments @ 90? 05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 8 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 8 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  53  Figure 54: Comparison of 8 mm results with DIN 1052:2004-8 adjustments @ 45?   Figure 55: Comparison of 8 mm results with EC 5 adjustments @ 45? 05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 8 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 8 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  54  Figure 56: Comparison of 8 mm results with DIN 1052:2004-8 adjustments @ 30?   Figure 57: Comparison of 8 mm results with EC 5 adjustments @ 30? 05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 8 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity05101520253035404550550 5 10 15 20 25 30 35 40 45 50 55Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 8 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  55  Figure 58: Comparison of 10 mm results with DIN 1052:2004-8 adjustments @ 90?   Figure 59: Comparison of 10 mm results with EC 5 adjustments @ 90? 051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 10 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 10 mm @ 90? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  56  Figure 60: Comparison of 10 mm results with DIN 1052:2004-8 adjustments @ 45?   Figure 61: Comparison of 10 mm results with EC 5 adjustments @ 45? 051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 10 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 10 mm @ 45? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  57  Figure 62: Comparison of 10 mm results with DIN 1052:2004-8 adjustments @ 30?   Figure 63: Comparison of 10 mm results with EC 5 adjustments @ 45? 051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Adjusted withdrawal resistance DIN 1052:2004-8 [kN] W?rth 10 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity051015202530354045505560657075800 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80Experimental withdrawal resistance [kN] Adjusted withdrawal resistance Eurocode 5 [kN] W?rth 10 mm @ 30? angle Douglas-fir - 4dSPF - 4dHem.-fir - 4dDouglas-fir - 10dSPF - 10dHem.-fir - 10dDouglas-fir - 12dSPF - 12dHem.-fir - 12dDouglas-fir - 16dSPF - 16dHem.-fir - 16dtens. capacity  58 4.  CONCLUSIONS AND RECOMMENDATIONS 4.1. Conclusions Results of this study show that self-tapping wood screws have a high resistance against pull-out in Canadian Major Species. Combined with their hardened high tensile strength steel, these STS connectors can be effectively used in reinforcement applications and direct connections.  To utilize the high withdrawal capacity of self-tapping wood screws most efficiently, they should be installed in such way that the main path of load transfer is along the length axis of the self-tapping wood screw.  This study has shown that in most cases the equation given in the German DIN predicts the withdrawal capacity conservatively. However, some cases are under-predicted and therefore seem unsafe. The EC 5 equation over-predicts the withdrawal capacities of the screws. The findings clearly show that improvements to the equations need to be done in order to apply them to major Canadian species. Nevertheless, more data on the withdrawal resistance of self-tapping wood screws in major Canadian species is required to develop such improved equations. When comparing the test results to the equivalency calculations according to CSA O86-09 and the NDS 2005 (Equations 3 to 7), it becomes apparent that none of the currently available calculation methods for mechanical fasteners can predict the withdrawal capacity of self-tapping wood screws. Not only are the predicted values much too conservative, but the currently available equations also failed to include a parameter for the angle of the screw axis relative to the angle of the grain. While the European   59 equations are valid for screw inclinations between 90 degree and 30 degrees, the North American equations are only valid for 90 degree screw angles. In order to fully utilize the high capacities and therefore advantages of STSs, modifications to CSA O86-09, as well as NDS 2005 are required. In lieu of changing the available equations in the North American code, they could be complimented by adopting an additional section for self-tapping wood screws or fasteners with a thread type similar to that of STSs. Alternatively, for the immediate future, proprietary construction approval, or product evaluation reports valid for an individual screw type and manufacturer could be used to overcome the missing calculation methods in the available codes.   4.2. Recommendations The experimental research needs to be continued  to 1) increase sample size to allow proper estimation of characteristic values and 2) complete the parameter study for the withdrawal resistance of screws from different manufacturers such as the     HECO TOPPIX CC and SPAX to confirm the findings of the study.  Furthermore, the effects of multiple self-tapping screws and respective end and edge distances, as well as spacing?s of these screws between each other need to be studied. Such studies should include conditions like changing moisture conditions during the service life of a connection, as well as during the seasons of the year. In the Canadian context reliability based design procedures need to be considered to establish design equations for STS.   60 In order to fully understand the behaviour of connections using self-tapping wood screws, further studies of the capacities of such screws perpendicular to their length axis as well as combined forces applied parallel and perpendicular to the axis of the screw are needed. In most cases combined forces will have to be transmitted and resisted by the self-tapping wood screws. Such tests have been conducted in Europe by Bla? and Bejtka (2004) to increase the range of application of STSs. In addition, more studies should be conducted to build on UBC?s work on using these screws to reinforce moment resistant connections against perpendicular to the grain and shear failures. The feasibility of reducing end and edge distances, as well as bolt and row spacing in moment resisting connections and heavy timber connections in general could be studied. The reduction of such parameters would allow for more economical use of timber members in structures and potentially lead to a greater use of wooden members in mid-rise and commercial structures. In almost all cases, the current minimum distances are the limiting factor in sizing wooden members in structures of such nature.    61 BIBLIOGRAPHY ANSI / AF&PA NDS-2005 (2005), NDS: National Design Specifications for Wood Construction. AF&AP American Wood Council, Washington Bejtka I., Bla? H.J. (2005) Self-tapping screws as reinforcements in connections with dowel-type fasteners. International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures. Meeting Thirty-Eight, Karlsruhe, Germany Bla? H.J., Bejtka I. (2004) Selbstbohrende Holzschrauben und ihre Anwendungsm?glichkeiten. Holzbaukalender 2004, 3. Jahrgang, Bruderverlag Karlsruhe, ISBN 3- 87104-136-X, S. 516-541 (2004) Bla? H.J., Bejtka I., Uibel I. (2006) Tragf?higkeit von Verbindungen mit selbstbohrende Holzschrauben mit Vollgewinde. Karlsruher Berichte zum Ingenieurholzbau 4, Universit?t Karlsruhe, Germany Bla? H.J., Schmid M., Litze H., Wagner B. (2000) Nail plate reinforced joints with dowel-type fasteners. World Conference on Timber Engineering 2004. Whistler, British Columbia, Canada. Proceedings pp. 8.6.4-1 ? 8.6.4-8 CEN (Comit? Europ?en de Normalisation) (2004). EN1995-1-1: 2004 (D), Eurocode 5: Bemessung und Konstruktion von Holzbauten- Teil 1-1: Allgemeines- Allgemeine Regeln und Regeln f?r den Hochbau CEN/ TC 250 Structual Eurocodes. CSA (Canadian Standards Association) Standard (2009). CSA O86-09: Engineering Design in Wood. Canadian Standards Association, Mississauga DIBt (Deutsches Institut f?r Bautechnik) (2006) Allgemeine Bauaufsichtliche Zulassung, W?rth ASSY VG plus Vollgewindeschrauben als Holzverbindungsmittel. DIBt, Berlin DIN (Deutsches Institut f?r Normung e.V.) (1975) DIN 7998: Gewinde und Schraubenenden f?r Holzschrauben. Beuth Verlag, Berlin   62 DIN (Deutsches Institut f?r Normung e.V.) (2004) DIN 1052:2004-08: Entwurf, Berechnung und Bemessung von Holzbauwerken- Allgemeine Bemessungsregeln und Bemessungsregeln f?r den Hochbau. Beuth Verlag, Berlin DIN (Deutsches Institut f?r Normung e.V.) (2010) DIN 96: Halbrund-Holzschrauben mit Schlitz. Beuth Verlag, Berlin DIN (Deutsches Institut f?r Normung e.V.) (2010) DIN 97: Senk-Holzschrauben mit Schlitz. Beuth Verlag, Berlin DIN (Deutsches Institut f?r Normung e.V.) (2010) DIN 571: Sechkant-Holzschrauben. Beuth Verlag, Berlin DIN EN (Deutsches Institut f?r Normung e.V. ) (1999). DIN EN 1382: Holzbauwerke, Pr?fverfahren - Ausziehtragf?higkeit von Holzverbindungsmitteln. Deutsche Fassung EN 1382. Beuth Verlag, Berlin Gehloff M., Closen M., Lam F., (2010) Reduced edge distances in bolted timber moment connections with perpendicular to grain reinforcement. World Conference on Timber Engineering 2010. Riva del Garda, Italy, CD-ROM Proceedings Haller P., Birk T., Offermann P., Cebulla H. (2006) Fully fashioned biaxial weft knitted and stitch bonded textile reinforcements for wood connections. Science Direct, Composites Part B 37 278-285 Herzog Th. (Hrsg.) (2000) Expodach?roof structure at the world exhibition Hanover 2000. Prestel, Munich, London, New York Herzog Th., Natterer J., Schweitzer R., Volz M., Winter W. (2003) Holzbauatlas. Edition DETAIL, Inst. f. internationale Architektur-Dokumentation, Muenchen. Vierte Auflage, neu bearbeitet Hockey B. (1999) Truss Plate reinforced bolted connections in Parallel Strand Lumber. MASc Thesis, University of British Columbia, Department of Wood Sciences, Vancouver   63 Johansen KW (1949) Theory of Timber Connections. International Association of Bridge and Structural Engineering, Copenhagen, Publication No. 9, pp. 249-262 Killer J. (1998) Die Bauwerke der Baumeister Grubenmann. Lignum/Baufachverlag, 4. Auflage Lam F., Schulte-Wrede M., Yao C.C., Gu J.J., (2008) Moment resistance of bolted timber connections with perpendicular to grain reinforcements. World Conference on Timber Engineering 2008. Miyazaki, Japan, CD-ROM Proceedings Lam F., Gehloff M., Closen M., (2010) Moment-resisting bolted timber connections. Proceedings of the Institute of Civil Engineers, Volume 163 Issue SB4. London, UK, ISSN 0965-0911, pp. 267-274 Madsen B. (2000) Behaviour of Timber Connections. First Edition, Timber Engineering Ltd., North Vancouver, ISBN 1-55056-738-1 M?ller Ch. (2000) Holzleimbau Laminated Timber Construction. Birkh?user, Basel; Berlin; Boston, ISBN 0-7643-6267-7 (2000) Zimmer P. (2002) Die Konstruktionsgeschichte H?lzerner Br?cken zwischen 1750 und 1850. Interner Forschungsbericht, Fakult?t Architektur der TU Dresden   64 APPENDIX ? SUPPLEMENTAL MATERIAL  Figure 64: Load ? Deformation (6mm, 4d, 90?, Douglas-fir)  Figure 65: Load ? Deformation (6mm, 4d, 90?, S-P-F) 00.511.522.533.544.550 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  4d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1000.511.522.533.544.550 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  4d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  65  Figure 66: Load ? Deformation (6mm, 4d, 90?, Hemlock)  Figure 67: Load ? Deformation (6mm, 4d, 45?, Douglas-fir) 00.511.522.533.544.550 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  4d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1001234560 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  4d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  66  Figure 68: Load ? Deformation (6mm, 4d, 45?, S-P-F)  Figure 69: Load ? Deformation (6mm, 4d, 45?, Hemlock) 01234560 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  4d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1001234560 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  4d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  67  Figure 70: Load ? Deformation (6mm, 4d, 30?, Douglas-fir)  Figure 71: Load ? Deformation (6mm, 4d, 30?, S-P-F) 01234567890 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  4d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1001234567890 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  4d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  68  Figure 72: Load ? Deformation (6mm, 4d, 30?, Hemlock)  Figure 73: Load ? Deformation (6mm, 10d, 90?, Douglas-fir) 01234567890 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  4d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  10d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  69  Figure 74: Load ? Deformation (6mm, 10d, 90?, S-P-F)  Figure 75: Load ? Deformation (6mm, 10d, 90?, Hemlock) 024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  10d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  10d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  70  Figure 76: Load ? Deformation (6mm, 10d, 45?, Douglas-fir)  Figure 77: Load ? Deformation (6mm, 10d, 45?, S-P-F) 0246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  10d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  10d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  71  Figure 78: Load ? Deformation (6mm, 10d, 45?, Hemlock)  Figure 79: Load ? Deformation (6mm, 10d, 30?, Douglas-fir) 0246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  10d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1002468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  10d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  72  Figure 80: Load ? Deformation (6mm, 10d, 30?, S-P-F)  Figure 81: Load ? Deformation (6mm, 10d, 30?, Hemlock) 02468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  10d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1002468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  10d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  73  Figure 82: Load ? Deformation (6mm, 12d, 90?, Douglas-fir)  Figure 83: Load ? Deformation (6mm, 12d, 90?, S-P-F) 024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  12d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  12d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  74  Figure 84: Load ? Deformation (6mm, 12d, 90?, Hemlock)  Figure 85: Load ? Deformation (6mm, 12d, 45?, Douglas-fir) 024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  12d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  12d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  75  Figure 86: Load ? Deformation (6mm, 12d, 45?, S-P-F)  Figure 87: Load ? Deformation (6mm, 12d, 45?, Hemlock) 0246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  12d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  12d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  76  Figure 88: Load ? Deformation (6mm, 12d, 30?, Douglas-fir)  Figure 89: Load ? Deformation (6mm, 12d, 30?, S-P-F) 02468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  12d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1002468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  12d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  77  Figure 90: Load ? Deformation (6mm, 12d, 30?, Hemlock)  Figure 91: Load ? Deformation (6mm, 16d, 90?, Douglas-fir) 02468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  12d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  16d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  78  Figure 92: Load ? Deformation (6mm, 16d, 90?, S-P-F)  Figure 93: Load ? Deformation (6mm, 16d, 90?, Hemlock) 024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  16d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  6mm  16d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  79  Figure 94: Load ? Deformation (6mm, 16d, 45?, Douglas-fir)  Figure 95: Load ? Deformation (6mm, 16d, 45?, S-P-F) 0246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  16d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  16d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  80  Figure 96: Load ? Deformation (6mm, 16d, 45?, Hemlock)  Figure 97: Load ? Deformation (6mm, 16d, 30?, Douglas-fir) 0246810121416180 0.5 1 1.5 2 2.5 3Load [kN] Deformation [mm] W?rth  6mm  16d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1002468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  16d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  81  Figure 98: Load ? Deformation (6mm, 16d, 30?, S-P-F)  Figure 99: Load ? Deformation (6mm, 16d, 30?, Hemlock) 02468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  16d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1002468101214160 0.5 1 1.5 2 2.5 3 3.5Load [kN] Deformation [mm] W?rth  6mm  16d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  82  Figure 100: Load ? Deformation (8mm, 4d, 90?, Douglas-fir)  Figure 101: Load ? Deformation (8mm, 4d, 90?, S-P-F) 0123456789100 0.5 1 1.5 2 2.5 3 3.5 4 4.5Load [kN] Deformation [mm] W?rth  8mm  4d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10SPEC 110123456789100 0.5 1 1.5 2 2.5 3 3.5 4 4.5Load [kN] Deformation [mm] W?rth  8mm  4d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  83  Figure 102: Load ? Deformation (8mm, 4d, 90?, Hemlock)  Figure 103: Load ? Deformation (8mm, 4d, 45?, Douglas-fir) 0123456789100 0.5 1 1.5 2 2.5 3 3.5 4 4.5Load [kN] Deformation [mm] W?rth  8mm  4d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100123456780 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  4d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  84  Figure 104: Load ? Deformation (8mm, 4d, 45?, S-P-F)  Figure 105: Load ? Deformation (8mm, 4d, 45?, Hemlock) 0123456780 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  4d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100123456780 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  4d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9  85  Figure 106: Load ? Deformation (8mm, 4d, 30?, Douglas-fir)  Figure 107: Load ? Deformation (8mm, 4d, 30?, S-P-F) 0246810121416180 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  8mm  4d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100246810121416180 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  8mm  4d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  86  Figure 108: Load ? Deformation (8mm, 4d, 30?, Hemlock)  Figure 109: Load ? Deformation (8mm, 10d, 90?, Douglas-fir) 0246810121416180 0.5 1 1.5 2 2.5 3 3.5 4Load [kN] Deformation [mm] W?rth  8mm  4d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4 4.5Load [kN] Deformation [mm] W?rth  8mm  10d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  87  Figure 110: Load ? Deformation (8mm, 10d, 90?, S-P-F)  Figure 111: Load ? Deformation (8mm, 10d, 90?, Hemlock) 024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4 4.5Load [kN] Deformation [mm] W?rth  8mm  10d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012141618200 0.5 1 1.5 2 2.5 3 3.5 4 4.5Load [kN] Deformation [mm] W?rth  8mm  10d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  88  Figure 112: Load ? Deformation (8mm, 10d, 45?, Douglas-fir)  Figure 113: Load ? Deformation (8mm, 10d, 45?, S-P-F) 0510152025300 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  10d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100510152025300 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  10d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  89  Figure 114: Load ? Deformation (8mm, 10d, 45?, Hemlock)  Figure 115: Load ? Deformation (8mm, 10d, 30?, Douglas-fir) 0510152025300 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  10d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520250 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  10d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  90  Figure 116: Load ? Deformation (8mm, 10d, 30?, S-P-F)  Figure 117: Load ? Deformation (8mm, 10d, 30?, Hemlock) 05101520250 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  10d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520250 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  10d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  91  Figure 118: Load ? Deformation (8mm, 12d, 90?, Douglas-fir)  Figure 119: Load ? Deformation (8mm, 12d, 90?, S-P-F) 0510152025300 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  12d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100510152025300 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  12d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  92  Figure 120: Load ? Deformation (8mm, 12d, 90?, Hemlock)  Figure 121: Load ? Deformation (8mm, 12d, 45?, Douglas-fir) 0510152025300 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  12d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520250 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  12d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  93  Figure 122: Load ? Deformation (8mm, 12d, 45?, S-P-F)  Figure 123: Load ? Deformation (8mm, 12d, 45?, Hemlock) 05101520250 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  12d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520250 1 2 3 4 5Load [kN] Deformation [mm] W?rth  8mm  12d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  94  Figure 124: Load ? Deformation (8mm, 12d, 30?, Douglas-fir)  Figure 125: Load ? Deformation (8mm, 12d, 30?, S-P-F) 0510152025300 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  12d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100510152025300 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  12d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  95  Figure 126: Load ? Deformation (8mm, 12d, 30?, Hemlock)  Figure 127: Load ? Deformation (8mm, 16d, 90?, Douglas-fir) 0510152025300 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  12d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100510152025300 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  8mm  16d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  96  Figure 128: Load ? Deformation (8mm, 16d, 90?, S-P-F)  Figure 129: Load ? Deformation (8mm, 16d, 90?, Hemlock) 0510152025300 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  8mm  16d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100510152025300 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  8mm  16d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  97  Figure 130: Load ? Deformation (8mm, 16d, 45?, Douglas-fir)  Figure 131: Load ? Deformation (8mm, 16d, 45?, S-P-F) 0510152025300 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  16d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100510152025300 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  16d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  98  Figure 132: Load ? Deformation (8mm, 16d, 45?, Hemlock)  Figure 133: Load ? Deformation (8mm, 16d, 30?, Douglas-fir) 0510152025300 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  8mm  16d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520250 1 2 3 4 5 6 7Load [kN] Deformation [mm] W?rth  8mm  16d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  99  Figure 134: Load ? Deformation (8mm, 16d, 30?, S-P-F)  Figure 135: Load ? Deformation (8mm, 16d, 30?, Hemlock) 05101520250 1 2 3 4 5 6 7Load [kN] Deformation [mm] W?rth  8mm  16d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520250 1 2 3 4 5 6 7Load [kN] Deformation [mm] W?rth  8mm  16d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  100  Figure 136: Load ? Deformation (10mm, 4d, 90?, Douglas-fir)  Figure 137: Load ? Deformation (10mm, 4d, 90?, S-P-F) 0123456789100 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  4d  @ 90 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 100123456789100 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  4d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  101  Figure 138: Load ? Deformation (10mm, 4d, 90?, Hemlock)  Figure 139: Load ? Deformation (10mm, 4d, 45?, Douglas-fir) 0123456789100 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  4d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012140 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  4d  @ 45 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  102  Figure 140: Load ? Deformation (10mm, 4d, 45?, S-P-F)  Figure 141: Load ? Deformation (10mm, 4d, 45?, Hemlock) 024681012140 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  4d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10024681012140 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  4d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  103  Figure 142: Load ? Deformation (10mm, 4d, 30?, Douglas-fir)  Figure 143: Load ? Deformation (10mm, 4d, 30?, S-P-F) 02468101214161820220 1 2 3 4 5Load [kN] Deformation [mm] W?rth  10mm  4d  @ 30 deg.  -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1002468101214161820220 1 2 3 4 5Load [kN] Deformation [mm] W?rth  10mm  4d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  104  Figure 144: Load ? Deformation (10mm, 4d, 30?, Hemlock)  Figure 145: Load ? Deformation (10mm, 10d, 90?, Douglas-fir) 02468101214161820220 1 2 3 4 5Load [kN] Deformation [mm] W?rth  10mm  4d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  10d  @ 90 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  105  Figure 146: Load ? Deformation (10mm, 10d, 90?, S-P-F)  Figure 147: Load ? Deformation (10mm, 10d, 90?, Hemlock) 051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  10d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  10d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  106  Figure 148: Load ? Deformation (10mm, 10d, 45?, Douglas-fir)  Figure 149: Load ? Deformation (10mm, 10d, 45?, S-P-F) 051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  10d  @ 45 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  10d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  107  Figure 150: Load ? Deformation (10mm, 10d, 45?, Hemlock)  Figure 151: Load ? Deformation (10mm, 10d, 30?, Douglas-fir) 051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  10d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  10d  @ 30 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  108  Figure 152: Load ? Deformation (10mm, 10d, 30?, S-P-F)  Figure 153: Load ? Deformation (10mm, 10d, 30?, Hemlock) 051015202530350 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  10d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  10d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  109  Figure 154: Load ? Deformation (10mm, 12d, 90?, Douglas-fir)  Figure 155: Load ? Deformation (10mm, 12d, 90?, S-P-F) 05101520253035400 2 4 6 8 10Load [kN] Deformation [mm] W?rth  10mm  12d  @ 90 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520253035400 2 4 6 8 10Load [kN] Deformation [mm] W?rth  10mm  12d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  110  Figure 156: Load ? Deformation (10mm, 12d, 90?, Hemlock)  Figure 157: Load ? Deformation (10mm, 12d, 45?, Douglas-fir) 05101520253035400 2 4 6 8 10Load [kN] Deformation [mm] W?rth  10mm  12d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  12d  @ 45 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  111  Figure 158: Load ? Deformation (10mm, 12d, 45?, S-P-F)  Figure 159: Load ? Deformation (10mm, 12d, 45?, Hemlock) 051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  12d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  12d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  112  Figure 160: Load ? Deformation (10mm, 12d, 30?, Douglas-fir)  Figure 161: Load ? Deformation (10mm, 12d, 30?, S-P-F) 051015202530350 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  12d  @ 30 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  12d  @ 30 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  113  Figure 162: Load ? Deformation (10mm, 12d, 30?, Hemlock)  Figure 163: Load ? Deformation (10mm, 16d, 90?, Douglas-fir) 051015202530350 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  12d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520253035400 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  16d  @ 90 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  114  Figure 164: Load ? Deformation (10mm, 16d, 90?, S-P-F)  Figure 165: Load ? Deformation (10mm, 16d, 90?, Hemlock) 05101520253035400 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  16d  @ 90 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520253035400 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  16d  @ 90 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  115  Figure 166: Load ? Deformation (10mm, 16d, 45?, Douglas-fir)  Figure 167: Load ? Deformation (10mm, 16d, 45?, S-P-F) 051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  16d  @ 45 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  16d  @ 45 deg.  -  S-P-F SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  116  Figure 168: Load ? Deformation (10mm, 16d, 45?, Hemlock)  Figure 169: Load ? Deformation (10mm, 16d, 30?, Douglas-fir) 051015202530350 1 2 3 4 5 6Load [kN] Deformation [mm] W?rth  10mm  16d  @ 45 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520253035400 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  16d  @ 30 deg. -  Douglas-fir SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10  117  Figure 170: Load ? Deformation (10mm, 16d, 30?, S-P-F)  Figure 171: Load ? Deformation (10mm, 16d, 30?, Hemlock) 05101520253035400 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  16d  @ 30 deg.  -  S-P-F - Summary - SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 1005101520253035400 1 2 3 4 5 6 7 8Load [kN] Deformation [mm] W?rth  10mm  16d  @ 30 deg.  -  Hemlock SPEC 1SPEC 2SPEC 3SPEC 4SPEC 5SPEC 6SPEC 7SPEC 8SPEC 9SPEC 10

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