Recent seismic events worldwide have brought to light the significant destructive potential of near-field earthquakes, causing substantial damage to infrastructure. In contrast, over the last decade, there has been a growing focus on studying the effects of pulse-type ground motions associated with near-field seismic events. This work intends to investigate numerically the near-field ground motion’s impact on the seismic performance of a seismically designed steel box girder bridge using fragility analysis. The fragility curves, which display a spectrum of damage states from mild to collapse for the various damage indexes and for the sampled peak ground acceleration varied between 0.1 and 1.2 g, were constructed using the Incremental Dynamic Analysis (IDA). The fragility analysis and probabilistic damage model are developed using damage indices like pier drift and deck displacement. To assess the damage potential of various forms of ground motions, the four-span continuous box girder bridge was represented by lumped mass nonlinear finite element method, and the superstructure was modelled using an elastic beam element. The proposed probability-based damage estimation framework is expected to be a sophisticated model capable of predicting the seismic losses suffered by steel box girder bridges. The results suggest that ground motions pose a considerable risk to the bridge even at modest PGA levels. At the PGA of 0.6 g, the bridge sustains modest to severe damage from near-source earthquakes. The much higher failure probability at different damage states, particularly at the severe damage state, was attributable to the significantly higher variability of the findings in the case of near-field records.