The second edition of the North American Specification for the Design of Cold Formed Steel Structural Members was published in October of 2007 for use in Canada, Mexico, and the United States. This Specification contains two country specific a ppe ndices, namely Appendix A (ANSI/AISI S100- 07) for use in the US and Mexico and Appendix B (CSA S136- 07) for use in Canada. Both Appendix A and B require that a bolt stagger reduction factor of 0.90 be used when calculating the tearing failure strength [resistance] of a cold formed steel member in tension with staggered bolts. This 10% reduction was based on limited testing that was carried out by Dr. Roger LaBoube of the University of Missouri-Rolla, which has now changed its name to the Missouri University of Science & Technology . The objective of this study was to establish if this bolt stagger reduction factor is indeed necessary since the stagger term of [s 2 /4g] has been used in the steel industry for many years without such a reduction. Experimental testing of two and three staggered bolt tension members was carried out in the Structures Laboratory of the Department of Civil Engineering at the University of Waterloo. Based on the test results of the 1.6 mm, 2.1 mm, 2.9 mm, 4 mm, 5 mm, and 6 mm thick steel sheet, it can be concluded that the 0.90 bolt stagger reduction factor is not necessary for the steel plate thicknesses tested
