
A?DS Commentay PART XII: NAILS AND SPIKES 12.1-GENERAL nails to attach studs tobottom and top plates are standard practices accepted by most building codes. 12.1.1-General Provisions The provisionrecognizing the useof standard Provisions for common steelwire nails and spikes nailingschedules (126) inlieu of designing joints for havebeen part of the Specificationsince the 1944 specific loads was first introduced in the 1982 edition. edition. Threaded hardened-steelnails and boxnails were added in the 1962 edition and the 1977 edition, 12.1.2-Quality of Nails and Spikes respectively. 12.1.2.1 Standard diameters for thevarious types Differences in Nail Types. For thesame penny- of nails and spikes were tabulated in previous editions weightclassification and length, round spikeshave a ofthe Specification. In the 1991 edition, Federal larger shank diameter than common nails and may Specification FF-N-1O5B (70) is referenced as the basic have either a chisel point and countersunk oval head or dimensional standard. Paragraphs 3.6.5, 3.6.11.2, 3.16.9 a diamond point with a flat head. Spikes over 60d are and 3.9-Style 3 of this Federal Specification cover steel generally specified by length (57,70). wirebox nails, steel wire common nails,pallet or threadedhardened steel nails, andround steelwire Threaded or deformed shank hardened-steelnails spikes, respectively. Nails or spikes outside the diame- include both ring or annularly threaded and helically ter and length classes covered in the Federal Specifica- threaded nails. For equivalent pennyweight and length, tion for each type may be available. Provisions of the hardened-steel nails have a smaller shank diameter than 1991 editionmay be applied to suchnails or spikes common nails for pennyweights of 8d and larger. The when the applicable diameters and lengths are specified head diameter of 20d and smaller hardened-steel nails and used to detennine design values. is larger than that of the corresponding common nail but is smaller for largersizes (those over 4 inchesin The nailprovisions of the 1991 edition also apply length) (70). to common wire nails made of copper or aluminum alloy conforming to the sizes given for such metals in Box nailshave smallera shank diameter than FederalSpecification FF-N-105B. It isthe designer’s commonnails of equivalent pennyweight. The head responsibility to use appropriate bending yield strengths diameter ofbox nails is larger than that ofcommon for such metals when determining lateral design values nails for sizesless than 10d, is thesame for the 10d in accordancewith 12.3 andto assurethe tensile, to 16d sizes and issmaller for sizes 20d and larger bearing and shear strengths of the fastener are adequate (70). to resist loads being transferred through the fastener to Nail Specifications. The requirement that nails the wood members in the joint (see 7.2.3 of Specifica- intended for use in engineering construction be specified tion). by length and diameter wasintroduced in the 1986 12.1.2.3 The requirements for threadedhardened- edition. The specificationalso should include head steelnails have remain unchanged since the 1962 diameter if the nail is produced in more than one head edition. diameter for the same length and shank diameter; and thread type or head and pointtype if other than 12.1.3-Fabrication and Assembly common or box nails are to be used (70). 12.1.3.1 A limitation on the size of prebored holes General Construction. Most nailed joints in light for nails and spikeswas first introduced in the 1952 framewood construction are not engineered but are edition.Such holes werelimited to 75 percent of the made in accordancewith standard practices that have diameterof the fastener. In the 1962 edition, the been established from manyyears of field experience limitation waschanged to 90 percent forGroup I (126). Such practices are expressed in terns of nailing species, those having a specific gravity of 0.62 or larger; schedules which give the number, size and type of nail, and 75 percent for Group 11, I11 and IV species, those and the direction of driving (e.g. face nailing, toenail- having a specific gravity of 0.59 or less.These provi- ing) to be used for different connections. For example, sions were carried forward unchanged through the 1986 use of three 8d toenails to attach joists to a sill plate; edition. The limitation on preborednail and spike anduse of four 8d toenails or two 16d face or end holes remains the same in the 1991 edition except that 140 Nails and Spikes NDS Comentary the separation between the most densespecies and was dropped from the Specificationin favor ofthe other speciesis defined in terms of specific gravity withdrawal design value table alone. rather than fastener species groups. The latter are no longer used for connection design in the 1991 edition. Also inthe 1962 edition, provisions for assigning withdrawaldesign values to threaded hardenednails 12.1.3.2 Toenailing proceduresconsisting of slant were introduced. Suchnails were assigned the same drivingof nails at a 30” angle from theface of the withdrawaldesign values as those for common wire attached memberwith an end distance(distance be- nailsof the samepennyweight class. However, the tween end of side member and initial point of entry) of procedure was modified in the 1968 edition to account one-third the nail length have been part of the Specifi- for the fact that although the diameter of common wire cation since the 1952 edition. Based on lateral and nails increases as pennyweight class increases from 20d withdrawal tests of nailed joints in frame wall construc- to 60d, the diameters of threaded hardened nails in this tion (62,160), the toenail factors of12.2.3 and 12.3.7 range and larger do not. The diameter of 30d, 40d, presume use ofthese driving procedures and the 50d and 60d threaded hardened nailsis the same as absenceof excessive splitting. If suchsplitting does that (0.177inches) for the 20d nail of thistype, and occur, a smaller nail should be used. the diameter for 80d and 90d threaded hardened nails was the same as that (0.207inches) for the 70d size. 12.2-WITHDRAWAL DESIGN VALUES To adjust for these differences, the 20d to 60d thread- 12.2.1-Withdrawal fromSide Grain ed hardened nails wereassigned the samewithdrawal designvalue as that for20d commonnails having a Background diameter of0.192 inches. The 70d to 90d threaded hardenednails were assigned the samewithdrawal Withdrawal designvalues for nails and spikes are designvalue as that for acommon nail having a based on the equation diameter whichwas in the same ratio tothe 70d (C12.2-1) threaded hardenednail diameter of0.207 as the W = 1380 G5”D common to threaded nail diameter ratio for 20d nails, where: or 0.192/0.177. This equivalent diameter 0.225is inches, the diameter of a 40d common nail. For 20d W = nail or spikewithdrawal design value per and smallerpennyweights of threaded hardenednails, inch of penetration in member holding point, thesame withdrawal design values as those for the lbs equivalentsize common nails were used as inthe G = specificgravity of member holding point previous edition. based on oven dry weight and volume D = shank diameter of the nail or spike,in. Withdrawal designvalues for boxnails based on Equation C12.2-1were introduced inthe 1977 edition. Equation C12.2-1was based on earlyresearch The foregoingprocedures for establishingwithdrawal (56,64) and has beenused to establishnail and spike design values for nails and spikes were carried forward withdrawaldesign values since the1944 edition. unchanged through the 1986 edition. Withdrawal designvalues obtained from the equation represented about one-fifth average ultimate test values 1991 Edition Both Equation C12.2-1 and resultant tabulated mine which diameters apply to box nails, common nails withdrawaldesign values for common wirenails and and spikes. Withdrawal designvalues for threaded spikes by species were presented in the 1944 and 1948 hardened nails are givenin a separate portion of Table editions. In 1950, tabulated withdrawaldesign values 12.2A because of their different basis. Nails and Spikes 141 NDS Commentmy values for smooth-shank nailsinserted inpartially Ln /3 seasoned or wet wood that will seasonin service or p, = Ln - - (C12.2-2) cos 30" installedin dry wood that willbe subject to wetting and drying in service (see 7.3.3). = 0.615 Ln Clinching. It is to be noted that the withdrawal where: resistance of smooth-shank nails can besignificantly increased by clinching(35). Increases in withdrawal p, = penetration of nail in member holding point, resistanceof 45 to 170percent due to clinchinghave in. been reported when nails are tested soon after driving. Ln = lengthof nail, in. Wheninstalled in unseasoned or partiallyseasoned wood and tested after seasoning,increases of250 to 12.3-LATERAL DESIGN VALUES 460 percent as a result of clinching have been observed. 12.3.1-Wood-to-Wood Connections Clinching across the grain was found to give 20 perceut higherwithdrawal design values than clinchingalong Background the grain. When a greater assurance of a givenlevel of withdrawalresistance is needed with smooth-shank From the 1944 through the 1986 editions, lateral nails, clinching should be considered. design values for nails and spikes loaded at any angle to grain werebased on the equation 12.2.2-Withdrawal from EndGrain Z = KLD3" (C12.3-1) Reduction of withdrawaldesign values up to 50 percenthave been reported for nailsdriven in end where: grain surfaces (radial-tangential plane) as compared to side grain (radial-longitudinal or tangential-longitudinal 2 = nominalnail or spike lateral designvalue, planes)surfaces (57,160). When coupled with the Ibs effectsof seasoning in service after fabrication, such KL = species group constant based on specific reductions are considered too great for reliable design. gravity (G) of wood members It is considered to be on this basis that loading of nails = 2040 Group I G = 0.62 - 0.75 2ndspikes in withdrawal from end grain has been = 1650 Group I1 G = 0.51 - 0.55 prohibited in the Specificationsince the 1944 edition.
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