Abstract
The reactor building of a Mark II BWR plant is a complex reinforced concrete structure. The major earthquake resisting structural components of the reactor building are box and conical shell walls which are coupled in horizontal direction by floor slabs. To evaluate the dynamic behavior of a reactor building during very severe earthquake, time history response analyses are performed considering the nonlinear moment-rotation and shear stress-shear deformation characteristics of walls. The results of nonlinear analyses are compared with those of elastic analyses and the differences are examined. The maximum shear force and overturning moment of single cantilever model showed fairly good agreement with those of 3-cantilever model. The effect of maximum acceleration of the input motion on the nonlinear response of the structure are examined using El Centro and Hachinohe earthquakes. The difference of the change of response due to those two earthquakes are affected by the nonlinear behavior of the structure. The maximum strain energy of the member associated with its maximum strain caused by El Centro earthquake motion are evaluated, and it is shown that the maximum strain energy is nearly proportional to the square of the amplitude of the input motion to a certain level. The maximum member strain energy will be a good measure of the intensity of the earthquake effect on structure in nonlinear range in which stress or deformation are no longer proportional to the amplitude of input motion.
