Analytical Model for Sheathing-to-Framing Connections in Wood Shear Walls and Diaphragms Johnn P.Judd'and Fernando S.Fonseca,P.E.,A.M.ASCE2 ing con and cyclicn and doc sted Furt the model may be implemented nagera purpose finitemnt programsuchasornapcd structural analysis program such as CASHEWV To illustrate,the responses of a 88x146 m plywood diaphragm and a244x244 m oriented strand board shear wall are predicted using the new analytical model. D0t:10.1061ASCE)0733-9445(2005)131:2345) CE Database subject headings:Analytical techniques:Models:Shear walls:Diaphragms:Wooden structures:Framed structures. Introduction In wood hous o如wnek force is the tural ductility.TheR factor to determin ructures even at I ower loa walls and eventuallyinto the foundation.In Fig the primary shear walls and diaphragmsa of thestructure.nor oriented strand board (OSB)are fasteners (nals A displacement-based design requires an understanding of the 2002).This knowledge can be aca ired through experimenta es,in terms h shifting of st and lingwood 2002)lthouh the design philosophy yof the as not ch (SDOF）mMe d fo nd late I dis system, menta An at it may Displacement-based designs ed to have a numbe arault and).In the convention forced-based design. used to calibrate the model,and are seldom used for A number of spe ear wa analysis programs for wood deve g tha e ind .UT rof sheathing-to-fram connections (Tuomi and McCutcheor Kuo I A ,20 005.S these structural analysis programs,sheathing-to-framing connec onth.a w th tions are repres using a single n ovem ved on sumed to be rigid and pn panels ar JOURNAL OF STRUCTURAL ENGINEERINGASCE/FEBRUARY 2005/345 9d18Fb2009to222.66175206R rightAnalytical Model for Sheathing-to-Framing Connections in Wood Shear Walls and Diaphragms Johnn P. Judd1 and Fernando S. Fonseca, P.E., A.M.ASCE2 Abstract: A new analytical model for sheathing-to-framing connections in wood shear walls and diaphragms is discussed in this paper. The model represents sheathing-to-framing connections using an oriented pair of nonlinear springs. Unlike previous models, the new analytical model is suitable for both monotonic and cyclic analyses and does not need to be scaled or adjusted. Furthermore, the analytical model may be implemented in a general purpose finite element program, such as ABAQUS, or in a specialized structural analysis program, such as CASHEW. To illustrate, the responses of a 4.88314.6 m plywood diaphragm and a 2.4432.44 m oriented strand board shear wall are predicted using the new analytical model. DOI: 10.1061/(ASCE)0733-9445(2005)131:2(345) CE Database subject headings: Analytical techniques; Models; Shear walls; Diaphragms; Wooden structures; Framed structures. Introduction In wood housing, lateral forces caused by earthquakes or strong winds are usually resisted by a system of wood shear walls and diaphragms (roof and/or floors). Lateral force is transferred from the roof and floors through diaphragm action to supporting shear walls and eventually into the foundation. In Fig. 1, the primary structural components of wood shear walls and diaphragms are shown. Wood framing and sheathing panels, such as plywood or oriented strand board (OSB) are connected using fasteners (nails or staples). Additionally, shear walls may employ anchorage de￾vices and large diaphragms may require chord splice connections. Wood shear walls and diaphragms have generally performed well during earthquakes, in terms of preserving life. In spite of this performance, the costs of building damage to wood structures—for example, in the Northridge 1994 earthquake and 1992 Hurricane Andrew—have prompted an interest in shifting design emphasis from life safety to damage control (Rosowsky and Ellingwood 2002). Although the design philosophy of the current codes in North America has not changed from life safety, limiting structural damage may become a primary objective of next-generation performance-based design procedures (FEMA 2000). For wood structures, performance-based design may more precisely be termed displacement-based design because the pri￾mary objective is to limit interstory drift. Displacement-based design is considered to have a number of advantages compared to conventional force-based design (Fili￾atrault and Folz 2002). In the conventional forced-based design, the force required so that wood structures remain elastic is deter￾mined. The design force is then obtained by dividing the elastic force by a reduction factor R, which is used to account for struc￾tural ductility. The R factor is difficult to determine, however, because wood structures behave inelasticity, even at lower load levels. In a displacement-based design, the structure must meet a target displacement (such as interstory drift) instead of a force requirement. Thus, neither an elastic estimate of the structure, nor a reduction factor is necessary. A displacement-based design requires an understanding of the pushover (monotonic) response and energy dissipation character￾istics of the wood shear wall or diaphragm (Filiatrault and Folz 2002). This knowledge can be acquired through experimental testing and structural analysis. Although experimental testing can￾not be completely replaced, executing a structural analysis com￾puter program is typically less expensive and less time consuming compared to testing. For wood shear walls, a variety of structural analysis tools are available. The most simple tools consist of a single-degree-of￾freedom (SDOF) system (Medearis 1970; Stewart 1987; Foliente 1995; van de Lindt and Waltz 2003). In a SDOF system, the relationship between the applied force and lateral displacement at the top of a shear wall is calibrated to data from experimental testing. An advantage of using a SDOF system is that it may easily be employed in a subsequent dynamic analysis. Neverthe￾less, SDOF systems are limited to the specific materials and con- figurations used to calibrate the model, and are seldom used for wood diaphragm analysis. A number of specialized structural analysis programs for wood shear walls have been developed based on the understanding that the overall lateral behavior is dominated by the individual behav￾ior of sheathing-to-framing connections (Tuomi and McCutcheon 1978; Gupta and Kuo 1985, 1987; Filiatrault 1990; Dinehart and Shenton 2000; Folz and Filiatrault 2000; Richard et al. 2002). In these structural analysis programs, sheathing-to-framing connec￾tions are represented using a single nonlinear spring or a pair of orthogonal nonlinear springs. In general, wood framing is as￾sumed to be rigid and pin connected, and all sheathing panels are assumed to undergo the same rotation and translation. It is impor￾tant to note that this latter assumption is not valid for wood dia- 1 Graduate Student, Dept. of Civil and Environmental Engineering, Brigham Young Univ., 368 Clyde Building, Provo, UT 84602. 2 Associate Professor, Dept. of Civil and Environmental Engineering, Brigham Young Univ., 368 Clyde Building, Provo, UT 84602. Note. Associate Editor: J. Daniel Dolan. Discussion open until July 1, 2005. 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 November 4, 2003; approved on March 5, 2004. This paper is part of the Journal of Structural Engineer￾ing, Vol. 131, No. 2, February 1, 2005. ©ASCE, ISSN 0733-9445/2005/ 2-345–352/$25.00. JOURNAL OF STRUCTURAL ENGINEERING © ASCE / FEBRUARY 2005 / 345 Downloaded 18 Feb 2009 to 222.66.175.206. 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