ABSTRACT
A total of 14 steel sheathed single-storey shear wall tests (8 configurations) were carried out at McGill University by DaBreo (2011) (Table 1). The 1220 mm × 2440 mm walls consisted of ASTM A653 (2002) steel framing elements and a 0.46 mm or 0.76 mm thick sheathing panel attached on one side (Fig. 1). The sheathing was fastened to the frame with No. 8 × 19 mm pan head screws spaced at 50 mm, 75 mm, 100 mm or 150 mm over the wall perimeter and at 300 mm in the field. The frame was constructed using tracks (92.1 mm web, 38.1 mm flange) and studs (92.1 mm web, 41.3 mm flange and 12.7 mm lip) fastened together with No. 8 × 12.7 mm wafer head screws. The studs were placed at a distance of 610 mm o/c except at the wall ends where back-to-back chord studs were installed. A Simpson Strong-Tie S/HD10S holddown device was placed at each end of both chord studs to anchor the shear wall to the test frame (Fig. 1). In addition, blocking members were screw connected to the studs at the quarter points of each wall in order to restrain the twisting of the
1 INTRODUCTION
1.1 Current lateral design of CFS framing systems
Methods for the design in North America of coldformed steel frame/steel sheathed shear walls used as a seismic force resisting system have recently been developed (Balh et al., 2010; Yu & Chen, 2009; Yu et al., 2007; Serrette, 1997). These methods, which can be used in conjunction with the National Building Code of Canada (NRCC, 2005) and the North American Lateral Cold-Formed Steel Standard (AISI S213, 2007), were based on the results of tests on shear walls subjected to lateral loads alone. The studs in these walls did not have any additional lateral support elements other than the sheathing, and thus are described as ‘unblocked’. A limited number of these shear walls exhibited significant damage to the chord studs, which compromised the vertical and lateral load carrying capacity of the wall. Thus the research program was expanded to evaluate the performance of cold-formed steel frame / steel sheathed shear walls, constructed with blocked stud members (laterally supported), subjected to combined gravity and lateral loading.
