Nonlinear Finite Element Analysis of Prestressed Concrete Containment Vessel under Severe Accident Loads

Abstract

Prestressed concrete containment vessel act as a reliable leak tight barrier during the accident conditions. There is a growing demand to study nonlinear behavior of containment structure under severe accident loads in depth. This paper presents nonlinear finite element analysis of prsestressed concrete containment vessel under severe accident loads with consideration of material nonlinearity, penetrations, local reinforcement and temperature-dependent degradation characteristic of materials. To reflect the prestressing effects realistically, non-uniform distribution of effective prestressing along the tendon profile is explicitly considered and python scripts are developed to add the corresponding temperature drop value for each node of the prestressed tendons to ABAQUS input files automatically. Nonlinear finite element analysis for pressure only case and combined thermal and pressure case has been investigated in detail. Nonlinear finite element analysis results of the containment structure indicate that, thermal effects have negligible effect on pressure capacity of containment, considering the thermal effects, pressure capacity of containment decrease not more than 5% and margin of the containment still meets the requirements of not less than 2.5. The effect of temperature exhibit significantly influence on displacement response of containment structure, and the effect of temperature on the strain of liner and reinforcing steel is much greater than that on prestressed tendon. Thermal effects exhibit the greatest influence on nonlinear displacement response of the dome apex location and the least influence on the 33 m elevation.