超长大体积混凝土地下结构温度效应的确定及仿真

为了防止超长钢筋混凝土或者大体积混凝土结构出现温度裂缝而降低结构的耐久性能,需要对结构进行温度场和温度应力分析.基于热传导的基本理论阐述了超长大体积混凝土结构地下室温度场确定的方法,并以某实际超长大体积混凝土结构的地下室为例,确定了其结构内外部温度边界条件的取值,运用有限元软件ANSYS模拟了其运行期升温和降温2种最不利工况下的结构温度场,并对结构进行了温度应力计算分析.结果表明：对于超长结构或者大体积混凝土结构,在构件厚度方向存在温度梯度变化,在构件结点处也存在着分布复杂的温度场；离结构刚度中心越远,温度变形量越大；在墙转角、墙板接触、洞口下方均存在温度应力集中现象,且应力从这些地方向周围逐渐减小.

Determination and simulation of temperature effect on super-long and underground mass concrete structure

To prevent thermal cracks caused by temperature changes in super length concrete structures or massive concrete structures, this work defined the thermal boundary conditions and analyzed the thermal stress of the structures.Based on the basic theory of thermal conduction, a method to define the environment temperature that the structure served in was described. The basement of an actual super-long concrete structure was taken as an example to illustrate the method. The thermal boundary conditions were determined. Then, general finite element analysis was performed to on ANSYS simulate the thermal field of the structure under two worst cases including both temperature rising and temperature reduction. The calculation and analysis results of thermal stress showed that: the thermal stress gradient distribution varied along the thickness on the concrete members of the super-long structure, and the thermal fields in the joints of the concrete members were complex; the thermal deformation tended to be larger in the members further away from the center of stiffness; the stress concentration was distinctly in the turners of wall, interactions of wall and plate, under parts of hole, and the stress decreased as distance increased from the parts mentioned above.