The study focuses on conducting a mainshock-aftershock damage assessment of a reinforced concrete (RC) bridge. An RC bridge model was created using SAP2000 software. The study proposes a novel approach for evaluating the seismic vulnerability of structures affected by mainshock-aftershock sequences. The following study provides a detailed description of the methodology employed. Incremental dynamic analysis was performed utilizing ten distinct ground motions to generate fragility curves for various damage states of RC structure. The comparison of fragility curves for RC structure will be presented and discussed, allowing for an assessment of the impact of mainshock-aftershock sequences. The analysis conducted on the impact of both the mainshock and aftershock on the structure, utilizing drift ratio and Peak Ground Acceleration (PGA), provides valuable insights into seismic vulnerability. The fragility analysis emphasizes the importance of understanding how structures respond to seismic events of differing magnitudes. The identification of damage thresholds across various damage states underscores the need for robust seismic design and retrofitting strategies to mitigate potential structural vulnerabilities. This analysis will significantly contribute to the field of seismic engineering by enhancing our understanding of structural behavior under seismic loading conditions and informing future mitigation strategies.