Temperature Field Characteristics of Flat Steel Box Girders Based on In Situ Field Measurement and Numerical Simulation

Accurate assessment of temperature characteristics of flat steel box girders (FSBGs) is of great significance for the design, construction, and maintenance of long-span bridges. However, the inflow wind speed has been routinely adopted in the conventional thermal analysis on FSBGs; this ignores the actual wind field around the FSBGs and might result in inaccurate assessment of temperature characteristics of FSBGs. In this study, a novel thermal analysis approach is proposed to evaluate the temperature characteristics of FSBGs, which accounts for the nonuniform wind distribution at the thermal boundary layer thickness (Ua) around the FSBGs. To achieve this, a wind adjustment factor derived via computational fluid dynamic simulations is employed to correlate the inflow wind speed and Ua. The feasibility and accuracy of the proposed thermal analysis approach is validated through field measurements. Subsequently, four indices, i.e., effective temperature (ET), vertical temperature difference (VTD), transverse temperature difference (TTD), and local temperature different gradient (LTDG), are adopted for evaluating the temperature field characteristics of FSBGs of a prototype bridge. Finally, a parametric study is performed to investigate the influence of several key parameters on the temperature field characteristics of FSBGs. These research methods and conclusions can provide valuable references for the thermal design, monitoring, and control of long-span bridges employing FSBGs as the main girders.