Stress analysis of shell structures considering the stiffness variations caused by cracking or openings

In electric power industries, much of reinforced concrete or prestressed concrete shell structures, such as LNG tank, outer shielding wall of nuclear power stations have become to be constructed these several years. In this report a finite element method using the axisymmetric ring element which has non-axisymmetric rigidity subjected to non-symmetric loads is proposed for analysing shell structures. This method can consider the effect of cracking and opening of thick shell structure by reducing rigidity of ring element. Applying this method to the model of the outer shielding wall of nuclear power station subjected to static seismic load, it is shown that this method is very efficient in the nonlinear analysis of shell structure. (author)