The Research On Temperature Effect Of Superelevation Concrete Filled Steel Tube Structure

Due to the excellent mechanical properties, concrete filled steel tube(CFST) structure is widely used in modern architecture. However, under the periodic ambient temperature and solar radiation, the temperature of inner concrete is obviously lag behind the one of steel tube surface, so larger temperature gradient and thermal stress will occur in the core concrete, even lead to the void of confinement effect and the incontrollable of inner forces in the composite structure.Based on the solar physics and heat transfer theory, the heat transfer mechanism between CFST and environment is studied, the mathematical model of solar radiation temperature effect is established. In view of the theoretical analysis, experiment measurements, finite element simulation, the temperature effect and change laws of CFST which affected by ambient temperature, air convection and solar radiation are studied.Further more, rely on GuangZhou Tower, the temperature effect of superelevation structure is analyzed. Focus on the temperature distribution along the height direction and circumferential direction, the distribution laws of temperature field which change with time and sunshine incidence angle are identified.Along the radial direction, the sunny side is subjected to the direct solar radiation, and the temperature is significantly higher than the shady one. Owing to the hysteresis of concrete, the heat energy can not be effectively transfer to the shady side, so the remarkable temperature difference is generated, the concrete tube will bended to the shady side and the larger lateral deformation is produced. Along the height direction of tower, convection and ambient temperature are affected by the altitude and time, it is a complex three-dimensional model. The different sections of the same column maybe in sunny or shady, suffered different solar intensity, and the convective heat transfer coefficient is changed with the increase of altitude, therefore, vertical temperature difference will occur in the same column.Meanwhile, the temperature field of GuangZhou Tower which under solar radiation is tested by using infrared camera, and the temperature distribution in daily maintenance is described and analyzed. The results of testing are compared with the FEM simulation results. It indicate that these two methods are in consistent with each other, the trend of temperature field is in harmony, just a slight deviation in the value details.