Standard slip factor tests for friction-type bolted joints are commonly used to evaluate the slip factor. In these tests, slippage is defined by the load drop and a constant displacement threshold assumed to be independent of joint geometry. However, because relative displacement is influenced by joint geometry, this definition cannot capture such effects. To develop a more general displacement-based slip definition, this study reviews standard slip test procedures in major international design codes. Finite element analyses and experiments examine the slip behavior of slip-critical and yield-critical joints. Based on these results, a unified slip definition is proposed, in which slip is identified when the slip displacement between the connected and splice plates reaches 0.1 mm.
