Behaviour and design resistance of long bolts in shear

The European standard EN 1993-1-8 lacks specific design provisions for bolted connections incorporating long bolts, despite their increasing use in innovative joint configurations. Long bolts are defined as structural bolts that are manufactured from circular steel, fully or partially, threaded rods instead of a steel coil and are not subjected to heat treatment. In contrast to standard structural bolts, they do not present a bolt head. They are assembled with standard washers and nuts at both ends and feature an extended length compared to standard bolts, offering unique advantages in addressing challenges that conventional bolts cannot resolve. Within the framework of the RFCS CONNECT4C project, which focuses on promoting circular economy principles in steel construction, adaptable and reusable steel joints are being developed, with long bolts playing a key structural role. As part of this initiative, the present study explores the mechanical performance of long bolts subject to shear through an extensive experimental campaign involving 60 tests. The aim is to characterise their behaviour and assess the applicability of the existing EN 1993-1-8 formulations for shear resistance and stiffness to this specific bolt type. Finally, a reliability assessment is conducted to establish a suitable partial factor ( γ M2 ) for connections utilising long bolts, confirming that the values for standard bolts are appropriate for long bolts in shear. The outcomes provide direct guidance for incorporating long bolts into future CEN product standards and extend the current design provisions of EN 1993-1-8 to long bolts. • Experimental investigation of long bolts in shear. • Shear resistance and stiffness validation for inclusion in EN 1993-1-8. • Reliability assessment of γ M2 partial factor.