升温过程中混凝土构件轴向变形简化计算

混凝土的热惰性将导致构件截面温度分布的不均匀性,由此必然产生温度变形差。采用有限元和试验验证相结合的方法,对影响混凝土构件温度变形差的主要因素进行了热-力耦合分析,确定了构件截面尺寸和升温速度等因素的影响程度,并给出温度变形差和等效温度的简化计算公式。有了等效温度,即可将升温过程中混凝土构件轴向变形转化为按截面温度分布均匀计算。同时,它可用来分析不均匀温度场引起的力学问题。

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.