SIMPLIFIED CALCULATION OF AXIAL DEFORMATION OF CONCRETE MEMBERS EXPOSED TO HIGH TEMPERATURE

Concrete thermal inertia will result in a nonuniform temperature distribution in the cross section of concrete members exposed to fire and soon afterwards the corresponding strain will be induced. This strain is called the nonuniform temperature distribution strain (NTDS). By finite element method and based on known test results, the thermal-stress coupled properties of the NTDS are analyzed; the influencing extent of these factors, such as the size of cross section, velocity of heating, etc., are determined, and the corresponding simplified calculation formulae for the NTDS and the equivalent temperature are developed. The simplified analysis can transform the problem of the axial deformation induced by the NTDS to that of a uniform temperature distribution in the cross section of concrete members, and the equivalent temperature can be used to analyze mechanical problems of concrete under elevated temperature.