Executive Summary

A review of four North American design specifications has indicated some discrepancies
between the various design specifications. The 2005 edition of the AISC specification is
the only one to provide guidance for the design of connections to prevent slip at the
service load and the factored load levels. Design issues that need to be reviewed for the
design of slip-critical joints are the evaluation of the slip resistance of joints, which
depends on the slip coefficient associated with the faying surfaces and the clamping force
provided by the bolts. These two quantities show considerable variation. In order to
assess the level of safety offered by slip-critical connections at service and factored load
levels, the mean values, and the variation of the slip coefficient and clamping force must
be included in a reliability analysis. The main objective of this preliminary study of the
slip resistance of bolted joints was to collect available test data on the slip resistance of
bolted joints, assess their applicability for a reliability analysis, and make use of the
available data to assess the required performance factor for the prediction of the slip
resistance at the ultimate limit state level.

Another objective of this investigation was to determine the consequence of slip-in
typical long-span roof trusses with bolted gusset plate connections with regular and
oversized bolt holes.

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This research was done in collaboration with The Natural Science and Engineering Research Council of Canada.