APA Engineered Wodd Handbooks Episode 10 ppt

8.1 CHAPTER EIGHT MECHANICAL FASTENERS AND CONNECTIONS* Zeno A. Martin, P.E. Associate Engineer, TSD 8.1 INTRODUCTION Everyone understands the concept that a chain is only as strong as its weakest link, and connections are the critical link between elements of a structure. Connections maintain load path continuity and provide structural integrity. When the importance of proper connection details is overlooked, structural failure can occur due to this weak link. Properly designed and detailed connections are what hold a structure together, and the designer needs to understand some fundamental principles asso- ciated with connections for wood structures: • Since the consequence of connection failure is severe, the design values have relatively high built-in factors of safety and relatively low probabilities of failure under design loads. • Fasteners and connectors for wood have continued to improve over the years, resulting in more reliable and accurate design guidelines—such as those presented in this chapter. • Strength or serviceability failures usually occur due to poor design or construction practices—basically, not following design guidelines. The guidelines in this chapter provide safe and reliable connections. Further- more, this chapter addresses common issues to help avoid potential problems such as how to specify nails correctly and accurately and also how to remedy common field problems such as overdriven fasteners. These guidelines mostly follow those of the National Design Specification for Wood Construction (NDS), 1 with additional information on fastening engineered wood products from APA—The Engineered Wood Association (APA) 2 recommendations and other sources as referenced. *The author gratefully acknowledges Keith Faherty for his permission to use excerpts of his previous work on this topic as published in the McGraw-Hill Wood Engineering and Construction Handbook, 3rd edition, 1999. 8.2 CHAPTER EIGHT 8.1.1 Types of Fasteners Many types of fasteners and connectors are available for use in attaching one wood structural unit to another. Some of the common types include nails, screws, lag screws, bolts, power-driven fasteners (special nails and staples), and thin-gauge steel plate connectors. Other connector types are split rings, shear plates, timber rivets, dowels, drift pins, and metal plate connectors. Some of these are shown in Fig. 8.1. • Nails are generally used when loads are light. They are used for light-frame construction, diaphragms, and shear walls. It has been reported that the average home has a many as 70,000 nails. 3 For increased installation efficiency, many nails are now installed with pneumatic nailers. • Screws are not as frequently used as nails or lag screws in wood construction. But they are more satisfactory than nails under vibratory or withdrawal loads, since they have less tendency to work loose. • Lag screws, bolts, and timber connectors are used for large elements and in light- frame construction when loads of relatively large magnitude must be transferred. Bolts are less efficient than split rings or shear plates; however, they are often adequate. Lag screws are used when bolts are undesirable, when the member is too thick, or when one face of the member is not accessible for the installation of washers and nuts. Lag screws can be used in conjunction with split rings and shear plates and are especially effective for large magnitude withdrawal loads. • Split rings and shear plates are used for connections in heavy timber construction. They also may be used in wood trusses when spans are relatively long and the trusses are widely spaced, causing high connection forces. • Thin-gauge steel plate connectors are used extensively to join wood structural elements, fasten one subassembly to another, and anchor a structure to its foun- dation. Many different types of proprietary steel plate connectors are commer- cially available, including joist and purlin hangers, beam seats, column caps, strap ties, framing anchors, seismic and hurricane anchors, mud sills, hold-downs, col- umn bases, and many others. Toothed sheet-metal plates are used extensively in the construction of light wood trusses, trussed rafters, and trussed floor joists. One or more of these types of structural components are used in approximately 90% of all residential structures, and they are also widely used in commercial and institutional buildings. • Corrosion-resistant fasteners are available and used when the wood elements are in high moisture environments and/or have been chemically treated to resist de- cay or fire. 8.2 CONNECTION DESIGN For many fasteners, nominal design values are defined by a table or equation in the National Design Specification for Wood Construction (NDS) 1 and are based on a certain set of assumed end-use conditions such as normal load duration (10-year), dry condition of use, no sustained exposure to elevated temperatures, and others. The word ‘‘nominal’’ is used in this chapter and in the NDS to describe a fastener design value of preassumed end-use conditions. After actual anticipated end-use conditions are accounted for by applying all appropriate adjustment factors, an MECHANICAL FASTENERS AND CONNECTIONS 8.3 FIGURE 8.1 Various fasteners and connectors: (A) column cap, (B) column base, (C) truss plate, (D) hold-down, (E) framing anchor, (F) joist hanger, (G ) T-strap tie, (H ) toothed sheet-steel plate, (I) nail, (J) screw, (K ) lag bolt, (M ) plywood clip, (N ) split ring. 8.4 CHAPTER EIGHT allowable design value is obtained that can be equated to the design load require- ments. Provisions are usually given for calculating nominal design values for various types of single fasteners. When a connection has multiple fasteners of similar size and type, the total connection strength is a summation of the strength for each individual fastener with the appropriate adjustment to account for group action. For nails, spikes, bolts, lag screws, and wood screws, the lateral load design values can be calculated by yield limit equations that account for the different potential yield modes—a mechanics-based approach often called the European yield model. Withdrawal load design values for these same fastener types can be calcu- lated from empirical equations. For other fastener types, such as split rings, shear plates, dowels, drift pins, and timber rivets, the lateral and withdrawal design values are generally obtained from empirically based tables. 8.2.1 Yield Model In the early 1990s, use of a fastener yield model, frequently referred to as the European yield model (EYM) for determining lateral load capacity was adopted in the United States. Research has shown that this model is fairly accurate to somewhat conservative in predicting actual fastener behavior. 4 Figure 8.2 shows the EYM failure modes. Mechanics-based equations predict yield for each mode, but due to the soft conversion process in NDS’s transition from the old empirical equations to the EYM, these EYM equations have different constants for different fastener types. For a given connection, each possible failure mode must be considered and the lowest capacity of the possible failure modes is taken as the design load for the connection. Since several or more equations must be considered, solutions with a computer, using a spreadsheet or other equation-solving software, can be time sav- ing. 8.2.2 Adjustment Factors Adjustment factors are used to account for end-use conditions that differ from those assumed for nominal design values. Generally, nominal design values are based on single fasteners having: a normal load duration (10 years of constant or cumulative loading), dry wood at the time of connection fabrication and in use, no sustained exposure to temperatures exceeding 100 ЊF, the fastener bearing perpendicular to the longitudinal axis of the wood grain, and adequate fastener penetration and spacing. When multiple fasteners are used in a connection, an adjustment is necessary to account for the group action. Although limited to certain connection types, several other adjustment factors are applicable, such as the metal side plate factor for split rings, shear plates, and timber rivets, the diaphragm factor for use in a mechanics- based method for diaphragm design, and the toe-nail factor for toe-nailed connec- tions. Allowable design values are determined by multiplying the nominal values by appropriate adjustment factors. Table 8.1 specifies which adjustment factors must be considered for different connections and load types, where Z, P, and Q refer to lateral loads in the three primary axes directions and W refers to withdrawal loads. Load-Duration Factor, C D . Wood-bearing (crushing) strength is dependent upon the duration of loading, due to damage accumulation in the wood material, and the same load-duration factors are applied to wood connections as are applied to other MECHANICAL FASTENERS AND CONNECTIONS 8.5 Mode I m Mode I m Mode I s Mode I s Mode II Mode III m Mode III s Mode III s Mode IV Mode IV (a) (b) FIGURE 8.2 Single-faster connection yield modes: (a) single shear connections, (b) double shear connections. 8.6 TABLE 8.1 Applicability of Adjustment Factors for Connection Load- duration factor* Wet- service factor† Temperature factor Group action factor Geometry factor‡ Penetration- depth factor‡ End- grain factor‡ Metal side plate factor‡ Diaphragm factor‡ Toe-nail factor‡ Bolts ZЈ ϭ ZC D C M C t C g C ⌬ ••• •• Lag screws WЈ ϭ W Z Ј ϭ Z C D C D C M C M C t C t • C g • C ⌬ • C d C eg C eg • • • • • • Split-ring and shear- plate connectors PЈ ϭ P Q Ј ϭ Q C D C D C M C M C t C t C g C g C ⌬ C ⌬ C d C d • • C st • • • • • Wood screws WЈ ϭ W Z Ј ϭ Z C D C D C M C M C t C t • • • • • C d • C eg • • • • • • Nails and spikes WЈ ϭ W Z Ј ϭ Z C D C D C M C M C t C t • • • • • C d • C eg • • • C di C tn C tn Metal plate connectors ZЈ ϭ ZC D C M C t •• • • • • • Drift bolts and drift pins WЈ ϭ W Z Ј ϭ Z C D C D C M C M C t C t • C g • C ⌬ • C d C eg C eg • • • • • • Spike grids ZЈ ϭ ZC D C M C t • C ⌬ ••• •• Timber rivets PЈ ϭ P Q Ј ϭ Q C D ن C D ن C M C M C t C t • • • C ⌬ ** • • • • C st *** C st *** • • • • *The load-duration factor C D shall not exceed 1.6 for connections. †The wet service factor C M shall not apply to toe nails loaded in withdrawal. ‡Specific information concerning geometry factors C ⌬ , penetration depth factors C d , end-grain factors C eg , metal side plate factors C st , diaphragm factors C di , and toenail factors C m is provided in Chapters 8, 9, 10, 11, 12 and 14 of the NDS. 1 ن The load-duration factor, C D , is only applied when wood capacity, P w or Q w , controls. See section on Timber Rivets. **The geometry factor, C ⌬ , is only applied when wood capacity, Q w , controls. See section on Timber Rivets. ***The metal side plate factor, C st , is only applied when rivet capacity (P r , Q t ) controls. See section on Timber Rivets. Source: This table is from AF&PA’s National Design Specification ௡ for Wood Construction. MECHANICAL FASTENERS AND CONNECTIONS 8.7 wood elements, with two exceptions. The first is that the impact load-duration factor (C D ϭ 2.0) is not allowed for connections. The second is when the capacity of a connection is controlled by the strength of a material other than wood, such as metal, concrete, or masonry. The allowable strength of these materials shall not be adjusted for load duration because they do not exhibit wood’s load duration behav- ior. The 1997 Uniform Building Code 5 (UBC) has more conservative load-duration factors for wind and earthquake loadings for all members, including connections, than does the NDS. For wind and earthquake loads, the UBC specifies C D ϭ 1.33, except that C D ϭ 1.6 can be used for nailed and bolted connections exhibiting mode III and IV behavior. The NDS and 2000 International Building Code 6 (IBC) permit C D ϭ 1.6 for wind and earthquake loads regardless of failure mode. Breyer et al. 7 report that C D ϭ 1.6 for modes III and IV in the UBC is permitted due to the greater energy dissipation attributes of these more ductile failure modes. They also report that 99% of the tabulated nail connection design values in the NDS are governed by modes III and IV, so the UBC and NDS are essentially in agreement regarding wind and seismic load duration factors for nailed connections. Reference 8 provides tables giving both the controlling failure mode and the tabulated nominal design values for nailed and bolted connections, as in the NDS. In this text, NDS provisions are followed, but the above discussion serves as a reminder to designers to verify local code acceptance of the appropriate load- duration factor. The load-duration factors are given in Chapter 1. Wet Service Factor, C M . The moisture content in the wood is considered both at the time of fabrication of the connection and as it will be in service. Dry use describes sawn wood elements with moisture contents of 19% or less and engi- neered wood products such as glulam and LVL with moisture contents of 16% or less. Most covered structures will remain continuously dry for the service life of the structure, and the issue of dry at fabrication pertains mostly to sawn lumber, which often does have higher moisture contents after the harvested wood is cut. However, most engineered wood products require a low moisture content for good adhesion in their manufacture, and thus engineered wood elements will almost always be dry at time of fabrication. Furthermore, many engineered wood products, such as I-joists, are manufactured for specific end-use applications and are intended to remain dry at all times. Nominal design values must be multiplied by the appropriate wet service factors specified in Table 8.2. Temperature Factor, C t . The temperature factor can usually be set equal to one, but for uncommon applications where the wood members and their connections will experience sustained exposure to elevated temperatures (above 100 ЊF), the nominal design values are to be multiplied by the appropriate temperature factors specified in Table 8.3. Group Action Factor, C g . Tests have shown that when more than two bolts, lag screws, or metal connectors (such as shear plates, split rings, and drift bolts and pins) are placed in a row, the distribution of force to the fasteners in the row is not uniform. The behavior of a group of fasteners is as follows: 9 1. As the number of fasteners in a row increases, the allowable load per fastener decreases. 8.8 CHAPTER EIGHT TABLE 8.2 Wet Service Factors for Connections Fastener type Moisture content At time of fabrication In-service Load Lateral Withdrawal Shear plates and split rings a Յ19% Ͼ19% any Յ19% Յ19% Ͼ19% 1.0 0.8 0.7 – – – Metal connector plates b Յ19% Ͼ19% any Յ19% Յ19% Ͼ19% 1.0 0.8 0.8 – – – Bolts, drift pins, and drift bolts Յ19% Ͼ19% any Յ19% Յ19% Ͼ19% 1.0 0.4 c 0.7 – – – Lag screws and wood screws Յ19% Ͼ19% any Յ19% Յ19% Ͼ19% 1.0 0.4 c 0.7 1.0 1.0 0.7 Nails and spikes Յ19% Ͼ19% Յ19% Ͼ19% Յ19% Յ19% Ͼ19% Ͼ19% 1.0 0.7 0.7 0.7 1.0 0.25 0.25 1.0 Threaded hardened nails any any 1.0 1.0 Timber rivets Յ19% Ͼ19% Յ19% Ͼ19% Յ19% Յ19% Ͼ19% Ͼ19% 1.0 0.9 0.8 0.8 – – – – a For split ring or shear plate connectors, moisture content limitations apply to a depth of 3 ⁄ 4 in. below the surface of the wood. b For more information on metal connector plates see NDS. 1 c C m ϭ 1.0 for wood screws. For bolt and lag screw connections with: (1) one fastener only, (2) two or more fasteners placed in a single row parallel to grain, or (3) fasteners placed in two or more rows parallel to grain with separate splice plates for each row, C m ϭ 1.0. Source: This table is from AF&PA’s National Design Specification ௡ for Wood Construction. TABLE 8.3 Temperature Factors, C t , for Connections In-service moisture conditions a C t T Յ 100ЊF 100ЊF Ͻ T Յ 125ЊF 125ЊF Ͻ T Յ 150ЊF Dry (1) 1.0 0.8 0.7 Wet 1.0 0.7 0.5 a Dry in-service for wood is defined as a moisture content of 19% or less and the wood remains under continuously dry conditions such as in most covered structures. Source: This table is from AF&PA’s National Design Specification ௡ for Wood Construction. MECHANICAL FASTENERS AND CONNECTIONS 8.9 2. If a connection contains more than two fasteners in a row: • An uneven distribution of fastener load occurs. • The two end fasteners carry a greater load than the interior fasteners, and with six or more fasteners in a row, the two end fasteners carry over 50% of the load. • The elastic strength of the connection will not increase significantly if addi- tional fasteners (more than six) are added to a row. 3. Small misalignment of bolt holes may cause large shifts in bolt loads. 4. Ultimate strength tests show that: • A slight redistribution of the load from the more heavily loaded end bolts to the less heavily loaded interior bolts occurs when wood crushing under the bolt is the mode of failure. • A partial specimen failure occurs before substantial redistribution takes place if final failure is in shear. Therefore, it is necessary in the design of a connection with more than two fasteners in a row to include a group action factor C g . 2n m(1 Ϫ m )1ϩ R EA C ϭ (8.1) ͫͬͩͪ g n 2n n[(1 ϩ Rm)(1 ϩ m) Ϫ 1 ϩ m ]1Ϫ m EA where n ϭ the number of fasteners in a row R EA ϭ the lesser of E s A s /E m A m or E m A m /E s A s E m ϭ modulus of elasticity of main member (psi) E s ϭ modulus of elasticity of side member (psi) A m ϭ gross cross-sectional area of main member (in. 2 ) A s ϭ gross cross-sectional area of side member, (in. 2 ) m ϭ 2 u Ϫ ͙u Ϫ 1 u ϭ s 11 1 ϩ ␥ ϩ ͩͪ 2 EA EA mm ss s ϭ center-to-center spacing between adjacent fasteners in a row (in.) ␥ ϭ load/slip modulus for connection, lb/in. ␥ ϭ (180,000)(D 1.5 ) for bolts or lag screws in wood-to-wood connections ␥ ϭ (270,000)(D 1.5 ) for bolts or lag screws in wood-to-metal connections D ϭ diameter of bolt or lag screw (in.) Tables 8.4 and 8.5 are based on Eq. (8.1). Effective Cross-Sectional Areas. In order to obtain the adjustment factor, C g , from tabular data provided in Table 8.4 and Table 8.5, the effective cross-sectional areas must first be determined as follows: 1. For load applied parallel to grain: Use the gross cross-sectional area of the member. 2. For load applied perpendicular to grain: The effective cross-sectional area is the product of the member thickness and overall width of the fastener group, see Example 8.2. If only one row of fasteners is used, use the minimum parallel- to-grain spacing of the fasteners as the width of the fastener group. 3. For load applied at an angle to grain: No guidance is provided by NDS; how- ever, based on engineering judgment, appropriate cross-sectional areas can be determined. 8.10 CHAPTER EIGHT TABLE 8.4 Group Action Factors, C g , for Bolt or Lag Screw Connections with Wood Side Members* for D ϭ 1 in., s ϭ 4 in., E ϭ 1,400,000 psi A s /A m † A s ,† in. 2 Number of fasteners in a row 23456789101112 0.5 5 12 20 28 40 64 0.98 0.99 0.99 1.00 1.00 1.00 0.92 0.96 0.98 0.98 0.99 0.99 0.84 0.92 0.95 0.96 0.97 0.98 0.75 0.87 0.91 0.93 0.95 0.97 0.68 0.81 0.87 0.90 0.93 0.95 0.61 0.76 0.83 0.87 0.90 0.93 0.55 0.70 0.78 0.83 0.87 0.91 0.50 0.65 0.74 0.79 0.84 0.89 0.45 0.61 0.70 0.76 0.81 0.87 0.41 0.57 0.66 0.72 0.78 0.84 0.38 0.53 0.62 0.69 0.75 0.82 15 12 20 28 40 64 1.00 1.00 1.00 1.00 1.00 1.00 0.97 0.99 0.99 0.99 1.00 1.00 0.91 0.96 0.98 0.98 0.99 0.99 0.85 0.93 0.95 0.97 0.98 0.98 0.78 0.88 0.92 0.94 0.96 0.97 0.71 0.84 0.89 0.92 0.94 0.96 0.64 0.79 0.86 0.89 0.92 0.95 0.59 0.74 0.82 0.86 0.90 0.93 0.54 0.70 0.78 0.83 0.87 0.91 0.49 0.65 0.75 0.80 0.85 0.90 0.45 0.61 0.71 0.77 0.82 0.88 *Tabulated group action factors (C g ) are conservative for D Ͻ 1 in., s Ͻ 4 in., or E Ͼ 1,400,000 psi. †When A s / A m Ͼ 1.0, use A m /A s and use A m instead of A s . Source: This table is from AF&PA’s National Design Specification ௡ for Wood Construction. Row of Fasteners. The following are considered to be a row of fasteners: 1. Two or more bolts of the same diameter loaded in single or multiple shear 2. Two or more connector units or lag bolts of the same type and size loaded in single shear 3. Adjacent staggered rows of fasteners that are spaced apart less than 1 ⁄ 4 the spac- ing between the fasteners in a row (see Fig. 8.3a) Examples of staggered fasteners are shown in Fig. 8.3. Example 8.1 Group of Fasteners Loaded Parallel to Grain Determine the group action factor for the bolted butt joint shown in Fig. 8.4. solution A m (3 ϫ 6) ϭ 2.5 ϫ 5.5 ϭ 13.75 in. 2 (8871 mm 2 ) A s (two 2 ϫ 6s) ϭ 2 ϫ (1.5 ϫ 5.5) ϭ 16.50 in. 2 (10,645 mm 2 ) Since A s /A m Ͼ 1.0, consider A m /A s ϭ 13.75 / 16.5 ϭ 0.833 Interpolating between A m /A s ϭ 0.5 and 1.0 for A m ϭ 12 in. 2 from Table 8.4 gives C g ϭ 0.87 ϩ (0.93 Ϫ 0.87)(0.833 Ϫ 0.5)/(1 Ϫ 0.50) ϭ 0.91 (conservative since based on A m ϭ 12 in. 2 ) Note: double interpolation from the tables or Eq. (8.1) can be used to obtain a less conservative exact value for C g . [...]... – 10d, 12d 6d 8d – 10d – 16d 20d 7d 8d 10d, 12d – – 12d 16d 59 76 86 97 102 108 123 54 70 79 90 94 100 114 48 62 69 79 82 87 100 47 60 68 77 81 86 98 0.048 (18 gauge) 0.099 0.113 0.120 0.128 0.131 0.135 0.148 0.162 0.177 0.192 0.207 – 6d – – 8d – 10d, 12d 16d – 20d 30d 6d 8d – 10d, 12d – 16d 20d 40d – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d 60 77 87 96 103 109 124 148 171 178 195 55 71 80 91 95 101 ... 40d – 60d 95 105 116 121 127 143 166 188 195 210 228 234 89 97 108 112 118 133 154 174 181 194 211 217 79 86 96 99 104 117 137 154 159 172 186 191 77 85 94 97 102 115 134 151 156 168 183 187 6d 8d – 10d, 12d – 16d 20d 40d – – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d – 60d 82 100 110 122 126 132 148 172 194 200 215 233 239 76 93 102 113 117 123 138 160 180 186 199 216 221 66 83 91 100 104 109 122 142... 76 79 90 105 114 124 134 147 151 39 49 54 61 63 66 75 89 96 105 115 126 130 38 47 53 59 61 65 73 87 94 103 112 123 127 0.099 0.113 0.120 0.128 0.131 0.135 0.148 0.162 0.177 0.192 0.207 0.225 0.244 – 6d – – 8d – 10d, 12d 16d – 20d 30d 40d 50d 6d 8d – 10d, 12d – 8d 20d 40d – – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d – 60d 61 79 89 101 104 108 121 138 148 157 166 178 182 55 72 80 87 90 94 105 121 130... 144 148 47 61 69 79 82 86 96 109 117 124 131 140 143 11⁄4 0.099 0.113 0.120 0.128 0.131 0.135 0.148 0.162 0.177 0.192 0.207 – 6dd – – 8dd – 10d, 12d 16d – 20d 30d 6dd 8dd – 10d, 12d – 16d 20d 40d – – – 7dd – 10d – – 12d 16d – 20d 30d 40d 61 79 89 101 106 113 128 154 168 185 203 55 72 81 93 97 103 118 141 154 170 186 48 63 71 80 84 89 102 122 133 145 152 47 51 69 79 82 88 100 120 130 140 147 1 ⁄2 Nail... 83 88 101 120 138 144 157 48 61 69 78 82 87 99 118 136 141 154 0.060 (16 gauge) 0.099 0.113 0.12 0.128 0.131 0.135 0.148 0.162 0.177 0.192 0.207 0.225 0.244 – 6d 6d – 8d – 10d 16d – 20d 30d 40d 50d 6d 8d – 10d, 12d – 16d 20d 40d – – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d – 60d 62 79 88 100 104 111 126 150 172 179 195 215 221 57 73 82 92 97 102 116 138 159 165 180 199 204 51 64 72 81 85 90 102 121... 50 63 71 80 83 88 100 119 137 142 155 171 176 0.075 (14 gauge) 0.099 0.113 0.120 0.128 0.131 0.135 0.148 0.162 0.177 0.192 0.207 0.225 0.244 – 69 – – 8d – 10d, 12d 16d – 20d 30d 40d 50d 6d 8d – 10d, 12d – 16d 20d 40d – – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d – 60d 65 82 91 103 107 113 129 152 175 182 198 217 223 60 76 85 95 99 105 119 141 162 168 183 201 206 53 87 75 84 88 93 105 124 142 148 161... 85 95 99 105 119 141 162 168 183 201 206 53 87 75 84 88 93 105 124 142 148 161 176 181 52 66 73 82 86 91 103 122 139 145 157 173 178 0 .105 (12 gauge) 0.099 0.113 0.12 0.128 0.131 0.135 – 6d – – 8d – 6d 8d – 10d, 12d – 16d 7d 8d 10d – – 12d 73 90 100 111 116 122 68 84 93 103 107 113 60 74 82 91 95 100 59 73 80 90 93 98 Nail diameter, in Pennyweight G ϭ 0.5 Douglas fir larch G ϭ 0.43 Hem-fir G ϭ 0.42 Sprucepine-fir... 158 162 48 58 64 70 73 76 85 99 106 114 122 132 136 47 57 62 68 70 74 83 96 103 111 119 129 132 1 0.099 0.113 0.120 0.128 0.131 0.135 0.148 0.162 0.177 0.192 0.207 0.225 0.244 – 6d – – 8d – 10d, 12d 16d – 20d 30d 40d 50d 6d 8d – – 10d, 12d – 16d 20d 40d – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d – 60d 61 79 89 101 106 113 128 154 168 183 192 202 207 55 72 81 93 97 103 118 141 151 159 167 172 181 48... 195 65 81 89 96 102 107 120 139 156 161 173 187 192 – 6d – – 8d – 10d, 12d 16d – 20d 30d 40d 50d 6d 8d – 10d, 12d – 16d 20d 40d – – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d 60d 82 107 121 137 144 152 170 194 215 222 236 252 258 76 99 111 126 132 141 158 180 200 206 219 234 240 66 86 97 111 116 123 140 160 178 183 194 207 212 65 84 95 106 114 121 137 157 174 179 190 203 208 – 6d – – 8d – 10d, 12d 16d... 0.17 in., KD ϭ 10D ϩ 0.5 for 0.17 in Ͻ D Ͻ 0.25 in 8.24 CHAPTER EIGHT TABLE 8 .10 Nail Lateral Load Design Values for Single-Shear Connections with Both Members of Identical Speciesa Side member thickness, in Common Box Sinker G ϭ 0.55 Southern pine – 6d – – 8d 10d, 12d 16d – 20d 30d 40d 50d 6d 8d – 10d, 12d – 16d 20d 40d – – – – – 7d 8d 10d – – 12d 16d – 20d 30d 40d – 60d 55 67 74 82 85 89 101 117 127 . Construction (NDS), 1 with additional information on fastening engineered wood products from APA The Engineered Wood Association (APA) 2 recommendations and other sources as referenced. *The author. 5d Perpendicular-to-grain spacing ϭ 10d Parallel-to-grain spacing ϭ 20d With prebored holes: End distance ϭ 10d Edge distance ϭ 5d Perpendicular-to-grain spacing ϭ 3d Parallel-to-grain spacing ϭ 10d The recommended. toenail factors C m is provided in Chapters 8, 9, 10, 11, 12 and 14 of the NDS. 1 ن The load-duration factor, C D , is only applied when wood capacity, P w or Q w , controls. See section on Timber Rivets. **The