A laboratory method of measuring slip in bolted connections

In a series of tests on high strength friction grip bolted connections having corrosion resistant treatment applied to the joint interfaces, it was necessary to measure the relative movement of the plates under applied loads in order to assess the performance of the joint. An instrument was required which would measure this movement and yet be unaffected by the strain induced in the plates by the load. As many test pieces were to be used, it was desirable that the instrument could be applied to the test piece as a unit to avoid a tedious setting up procedure. A gauge has been designed which satisfies the above requirements and in which the measurements of movements are repeatable to within 5 per cent. (A)