Concrete cracking simulations for nuclear applications

The need to understand concrete behavior under high temperatures in the nuclear industry has become rather acute. Previously, concrete has been used in nuclear industry as inexpensive material for construction and also for radiation shielding. Presently, we are concerned with the structural integrity of the containment, subject to accidental exposure of concrete to excessively high temperatures and chemical attack. Consequently, we are now seeking basic understanding of concrete behavior at extreme environmental condition. Indispensible in mathematical modeling of concrete behavior is the constitutive relation. A constitutive model developed by Takahashi 1] has been incorporated into the coupled thermal-stress analysis code, TEMP-STRESS, which gives the stress-strain relation up to the point of cracking. This paper describes the modeling of cracking behavior. Four crack propagation criteria: the J-integral, the energy release rate, the effective strength and the failure surface criterion are examined. Several numerical examples are given. Situations under which one method might be more convenient to use than the others are discussed.