Reliability assessment of existing bridges for military use — Appropriate values of partial factors for traffic loads

Freedom of movement and manoeuvre are key assumptions to success in any military operation and one of the core responsibilities for each corps of army engineers. The calculation of military loading capacity of any civilian bridge is one of the essential tasks to achieve this target. Partial factors for the traffic loading in standards for civilian use fail to adequately reflect conditions for assessing existing bridges under well-defined military loads. Based on the safety format adopted in an upcoming edition of STANAG 2021, the submitted contribution illustrates on how the partial factor for military traffic can be adjusted considering various crossing conditions. The numerical study, focused on a crossing of a MLC80 class vehicle over an existing bridge, reveals that the partial factor of the military traffic load can range from 1.1 up to 1.4, depending on the chosen crossing conditions and the target reliability level selected for the crossing mode under consideration.