Research on Solar Radiation-Caused Radial Temperature Difference and Interface Separation of CFST

Interface separation weakens the confinement between the steel tube and the core concrete, which is adverse to the superior bearing capacity and durability of the concrete-filled steel tube (CFST). In this study, an elaborate finite element model (FEM) of the temperature field was established and verified with temperature data obtained from the experimental segment. Based on this, the interface separation of CFST was calculated by the thermo-mechanical coupling method. In sight of the experimental and simulation results, the radial temperature difference (RTD) and interface separation showed nonuniform distribution along the circumference. Parametric analysis was carried out and clarified the influence of different parameters on the RTD and interface separation. Furthermore, simplified distribution of RTD and interface separation, and correlation coefficient of RTD were proposed and proved applicable for CFSTs with arbitrary parameter combinations. Finally, extreme value analysis (EVA) was conducted to predict the most unfavorable value of RTD and interface separation with a 100-year return period. The results show that the RTD can reach 42.11 °C and the maximum separation is 0.076 mm. The research results are expected to improve the design of the interface in CFST.