Analyzing the dynamic properties of an integrated system consisting of a box-girder bridge and a tunnel with a railway track is crucial for maintaining the structure's security, reliability, and operation. This inquiry is notably important because of its possible relevance to time-varying forces exterior forces, including vehicular and seismic loads, as well as the dynamic reaction of a moving train impacting the structure's connections. The interaction between these complex components under various loading conditions is crucial in determining the structure's behaviour and performance. Despite the critical importance of such analyses, previous studies have indicated a gap in the literature regarding the modal and dynamic analyses of integrated systems like the one under consideration. This research aims to fill this gap by focusing on the integrated structure's dynamic behaviour through comprehensive dynamic analyses. The primary aim of this investigation is to ascertain the dynamic response of the integrated system. The methodology employed in this study involves conducting dynamic analysis on the Finite Element Method model of the integrated system by ANSYS software. This approach allows a detailed examination of the structural response to different loading conditions and parameter variations. The study's outcomes are multifaceted and provide valuable insights into the dynamic response of the integrated structure. This finding underscores the importance of considering all integrated system components when analyzing its dynamic behaviour. Furthermore, the study evaluates the impact of various factors, such as vehicle speed, different loading conditions, damping ratio, and varying rock grades, on the structural response. Higher speeds were found to result in increased deformation, highlighting the significance of considering train speed in structural design and assessment. Additionally, the quality of the ground surrounding the Tunnel and beneath the railway line was found to have a substantial influence on deformation, velocity, acceleration, and stress levels. Notably, the study reveals that increasing the damping ratio significantly improves structural stability and performance, emphasizing the critical role of damping in designing resilient structures subjected to dynamic stresses from trains. This research contributes valuable insights into the dynamic analyses of the integrated structure comprising a box-girder bridge and a tunnel with a railway track, providing a comprehensive understanding of their behaviour under different loading conditions. This study's discoveries offer valuable suggestions for Tunnel, railway, and bridge engineers in identifying the most efficient design and maintenance strategy for this integrated structure. This work can be a foundation for future fatigue analysis of this integrated structure under dynamic vehicle load.
