Analyse dynamique d'un pont ferroviaire à grande vitesse : vitesses critiques et vérification selon EN 1991-2

As high-speed railway infrastructure continues to expand, bridge design can no longer rely solely on conventional static approches. Dynamic actions induced by railway traffic can give rise to resonance pheno-mena with potentially severe consequences for structural integrity and passenger comfort. This paper demonstrates the necessity of a rigo-rous dynamic analysis, based on the numerical modelling under Robot Structural Analysis of a 25 m-span reinforced concrete girder railway bridge, designed in accordance with Eurocodes EN 1990, EN 1991-2 and EN 1992-1-1. The study combines modal analysis, time-domain integration under the ten HSLM-A load models, and verification of the regulatory acceleration and deflection criteria. The results show that the dynamic response exceeds the admissible threshold under the HSLM-A load models (az,max = 7.19 m/s- for load model A10 at Vcrit = 170 km/h, against a=,dop = 3.5 m/s), with a dynamic amplification factor D = 1.97 at the service speed of 220 km/h. Critical non-conformities are identified over the range 130-190 km/h, which corresponds to the resonance speeds of the load models and is crossed during transient acceleration and deceleration phases. These results un-derscore the importance of systematically integrating dynamic analysis from the design stage. They also provide formal justification for the use of passive mitigation devices such as tuned mass dampers (TMD), thus constituting the analytical foundation required for their optimal design.