Seismic Performance Analysis of Railway Station Roofs under Complex Climatic Conditions in Cold Regions

High-speed railway stations with long-span steel structures are vulnerable to severe climatic conditions in cold regions, particularly when temperature differences, snow loads, and seismic events occur concurrently. This study develops a finite-element model of a large-span steel roof in a high-seismic, cold climate zone to assess the combined effects of extreme temperature differences, snow loads, and earthquakes. Results reveal that under coupled extreme loading, key roof components experience significant stress increases, and midspan vertical displacements exceed 450 mm—nearly double the design deflection limit of 240 mm. These deformations pose serious structural risks, including excessive stress concentration at critical joints and an increased likelihood of progressive collapse, particularly in the midspan regions. The findings highlight the need to revise current design codes to consider load combinations typical in cold-seismic environments and propose engineering strategies, such as enhanced joint design and snow load monitoring systems, to improve structural resilience.