Capacity of Oriented Strand Board Shear Walls with Overdriven Sheathing Nails Scott N.Jones'and Fernando S.Fonseca,P.E.,A.M.ASCE2 Abstract:Eight shear wall specimens sheathed with 11 mm structural oriented strand board panels were as embled with overdriver sheathing nails and tested using a nseudo-dynamic cedure specimens used 38x89 mm douglas fir-l arch framing members and 8o coolr,gun-driven sheathing nails Four overdriven nail depths were considered:fush,16,3.2,and 4.8mm.Nails were spaced at 76mm on center along the edges and 305 mm on center along intermediate supports.Edge nailing distance was 9.5 mm.Iwo specimens were con cn a ts c mine a lo cap 0%of the sh n a specime a shear wall.Comp ed to sr mens with flush-driven nails.s gth an reduced 56% D0:10.1061ASCE0733-9445(2002128:7898 CE Database keywords:Shear walls;Nails,Strength;Ductility:Wooden structures. Introduction code deficiencies as well as poor engineering.construction and are sheathing nails il s d h ed t mance Loss of e fop and headush with the surface of the sheathing materil.If a nail is diven per than this ideal depth.the nal is dered to that wood structures are prone to significant (H ditions are depicted in Fig.1.Gray and Zacher (19)repor one 96).F marily fro ce.In the ara of Northridge that was shaken by wit ed the nd docu g the Th team structed with flush-driven nails () sensus wa s that the stru he nage tured to nail framing members together and to slightly overdrive the nails.The overdriv ing allowed members being naile togethe Engincer.Wright Structural Engineers.Inc..7310 Smoke Ranch Rd. to be g la r sheath Provo.Ur 8460 E-mail nalls are us wever,the riving pin mus erepla drive depth to be adiusted at the nosepiece of the gun without the driving pin. ble publication 2000 1.2002.ASCE.ISSN 0733 ne na gun or if th 898/JOURNAL OF STRUCTURAL ENGINEERING/JULY 2002 d05Jn2009to222.65.175.206.Rcd yrigh Capacity of Oriented Strand Board Shear Walls with Overdriven Sheathing Nails Scott N. Jones1 and Fernando S. Fonseca, P.E., A.M.ASCE2 Abstract: Eight shear wall specimens sheathed with 11 mm structural oriented strand board panels were assembled with overdriven sheathing nails and tested using a pseudo-dynamic procedure. Specimens used 38389 mm Douglas Fir-Larch framing members and 8d cooler, gun-driven sheathing nails. Four overdriven nail depths were considered: flush, 1.6, 3.2, and 4.8 mm. Nails were spaced at 76 mm on center along the edges and 305 mm on center along intermediate supports. Edge nailing distance was 9.5 mm. Two specimens were constructed for each aforementioned overdriven depth. To determine a lower bound on capacity, 100% of the sheathing nails in a specimen were driven to the specified depth. Results from this study indicate that any level of sheathing-nail overdrive will reduce the capacity of a shear wall. Compared to specimens with flush-driven nails, specimens with nails overdriven 1.6 mm suffered 5% loss in strength and gained 1% in displacement capacity. Specimens with nails overdriven 3.2 mm had strength and displacement capacity reduced by 12 and 22%, respectively. Specimens with nails overdriven 4.8 mm fared poorly; strength was reduced 24%, and displacement capacity was reduced 56%. DOI: 10.1061/~ASCE!0733-9445~2002!128:7~898! CE Database keywords: Shear walls; Nails; Strength; Ductility; Wooden structures. Introduction Wood shear walls are the most prevalent lateral-force resisting system in houses and are very popular in low-rise commercial buildings in the United States. Historically, wood shear wall structures have fared very well in seismic events. The ability of a shear wall to deform and dissipate energy in a ductile fashion as it is subjected to lateral loading results in very good seismic perfor￾mance. Loss of life due to the failure of a properly designed and constructed wood shear wall system is uncommon. Collapse of such a structure during an earthquake is equally rare. The January 17, 1994 Northridge earthquake, however, proved that wood structures are prone to significant seismic damage when poor construction practices are prevalent ~Hall 1996!. Fol￾lowing the Northridge earthquake, three teams of engineers, pri￾marily from the City of Los Angeles Department of Building and Safety and the Structural Engineers Association of Southern Cali￾fornia ~SEAOSC!, scoured the shaken area and documented the damage to structures that occurred during the event. These teams were sponsored by the Earthquake Engineering Research Insti￾tute, the National Science Foundation, and the Federal Emergency Management Agency. The general consensus was that the struc￾tural damage incurred in wood buildings was due primarily to code deficiencies as well as poor engineering, construction, and/or inspection practices. Among the more prevalent structural deficiencies found in shear wall construction was overdriven sheathing nails. Overdriven sheathing nails are one of the major structural de- ficiencies in wood shear walls that are constructed with pneumatic nail guns. A properly driven nail should have the top of the nail head flush with the surface of the sheathing material. If a nail is driven deeper than this ideal depth, the nail is considered to be overdriven. Conversely, if a nail is driven more shallow than this ideal depth, the nail is considered to be underdriven. These con￾ditions are depicted in Fig. 1. Gray and Zacher ~1988! reported that in one wood-construction project the plywood shear walls had 80% of the nails driven to 3.2 mm or deeper below the sheathing surface. In the area of Northridge that was shaken by the earthquake, a large number of shear walls were found with over 50% of the nails overdriven. Shear walls with overdriven nails have reduced capacity as compared to those properly con￾structed with flush-driven nails ~Hall 1996!. Pneumatically driven nails are commonly under- or overdriven because of the driving pin. Nail guns were originally manufac￾tured to nail framing members together and to slightly overdrive the nails. The overdriving allowed members being nailed together to be ‘‘pressed’’ firmly and uniformly against each other. Nail guns are often accurate for some conditions, such as driving large 10d nails and 16d sinker. When thinner and shorter sheathing nails are used, however, the driving pin must be replaced with a shorter pin to prevent overdriving. Newer nail guns allow the drive depth to be adjusted at the nosepiece of the gun without replacing the driving pin. In addition, nails are under- or overdriven because guns are not firmly held by the carpenter, framing members are not prop￾erly supported, or framing members have nonuniform density. If the carpenter does not hold the nail gun firmly, or if the framing member being nailed to is not properly supported ~or is perhaps a 1 Engineer, Wright Structural Engineers, Inc., 7310 Smoke Ranch Rd., Suite P, Las Vegas, NV 89128. 2 Assistant Professor, Brigham Young Univ., Civil and Environmental Engineering, 368 Clyde Building, Provo, UT 84602. E-mail: ffonseca@et.byu.edu Note. Associate Editor: David V. Rosowsky. Discussion open until December 1, 2002. Separate discussions must be submitted for individual papers. To extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted for review and possible publication on October 12, 2000; accepted November 18, 2001. This paper is part of the Journal of Struc￾tural Engineering, Vol. 128, No. 7, July 1, 2002. ©ASCE, ISSN 0733- 9445/2002/7-898–907/$8.001$.50 per page. 898 / JOURNAL OF STRUCTURAL ENGINEERING / JULY 2002 Downloaded 05 Jan 2009 to 222.66.175.206. Redistribution subject to ASCE license or copyright; see http://pubs.asce.org/copyright