Temperature Field and Gradient Effects for Concrete-Filled Steel Tubular Truss Arch Bridges Under Construction

Long-span concrete-filled steel tubular truss arch bridges are extremely sensitive to thermal effects during cantilever construction, with non-uniform temperature distributions arising from mutual shading between members. The current standard JTG/T D65-06—2015 employs a simple gradient model that struggles to capture the temperature gradient characteristics of complex spatial trusses, failing to meet the demands of high-precision construction. Based on a truss-type steel arch bridge in Yunnan, a thermal conduction analysis framework is proposed to calculate the temperature field of the arch rib truss and its effects, and is validated by long-term monitoring data. The results indicate that the maximum temperature difference between the upper and lower chord tubes reaches 14.53 °C, significantly changing the secondary stress distribution. There is a significant negative correlation mechanism between arch rib elevation and solar radiation temperature, necessitating consideration of solar radiation temperature effects during arch rib assembly and closure. This study establishes an analytical method for the thermal effects of long-span steel truss arch ribs, laying the foundation for arch rib profile control and stress analysis.