The solar radiation induced spatiotemporal temperature distribution and time-varying temperature effect in long-span ballastless track continuous beam-arch bridge

The influence of a time-varying temperature environment on the mechanical performance and geometric alignment of long-span ballastless track continuous beam-arch bridge is significant. However, the structural temperature loads are often simplified into a single mode, making it difficult to accurately simulate the evolution of geometric alignment of long-span ballastless track continuous beam-arch bridge under time-varying temperature effects. To explore the spatiotemporal distribution characteristics of temperature fields and the evolution patterns of track geometric alignment in long-span ballastless track continuous beam-arch bridge, a refined analysis model for the time-varying temperature field is established incorporating ray tracing methods and real-time shadow techniques. Combining the temperature experiment results, the spatiotemporal distribution characteristic and evolution patterns of temperature across the bridge system and key sections are explored. Building on this foundation, the evolution of track geometric alignment on the bridge is analyzed, and the measures for controlling track geometric alignment are proposed. The research findings indicate that the surface temperature of the structure undergoes periodic changes throughout the day, and the orientation of the bridge significantly influences the temperature field of the beam-track structure. The vertical displacement extremes of the ballastless track on the bridge are positively correlated with the structural temperature. The track maintenance moments affect the track alignment on the bridge, but the extreme deformation of the ballastless track and the temporal variation pattern of the structural system temperature remain consistent. To minimize irregularities in the ballastless track geometric alignment on the bridge, adjustments to the track position during high-speed railway maintenance window should choose the moments close to the daily average temperature, aiming to decrease the effects of time-varying temperature on track irregularity.