A few issues on application of seismic design based on elastic-plastic analysis to piping systems

– Case study using a simple model –

Abstract

Two issues when performing seismic design for a piping system using elastic-plastic analysis were discussed using a simple model. First, elastic-plastic analysis of the piping model using elbow elements that can compute the elastic-plastic behavior was conducted. By compared with the results calculated using shell elements, it was shown that the elbow elements can be used for design analysis of the elastic-plastic region basically. Next, though the popular piping design is performed using the nominal outer diameter and nominal wall thickness, the dimensional tolerances of piping and the variations in material properties are not included in the design condition. This study showed that it is necessary to be careful about using the nominal dimensions for the elastic-plastic analysis of piping due to the variation in the analysis results for the model considering the tolerance of piping.