Thread effect on the initial stiffness of bolted connections

This paper investigates the effect of bolt threads on the initial stiffness of double-shear bolted connections through experimental tests and numerical analyses. Eight specimens composed of 4.7 mm and 8 mm thick structural steel plates with a bolt diameter of 20 mm having varying end distances are studied. The present finite element analysis demonstrates that, as the threads cut into the connected plate, they reduce the initial stiffness of the bolted connection, which is the reason why many finite element models in the literature could not reasonably match the load-displacement curves of tested bolted connection specimens. Comparisons against alternative models are presented, and the model incorporating bolt threads are found to be best able to mimic the actual load-displacement response up to the ultimate load.