Simplified, Detailed, and Isochronous Analysis and Test Results for the In-Plane Elastic-Plastic and Creep Behavior of an Elbow

Abstract

Predictions obtained from simplified and detailed MARC analyses are compared with experimental results for the elastic-plastic and creep behavior of a 16-in-dia 304 stainless steel piping structure subjected to an in-plane closing bending moment. The piping structure is composed of a 90-deg elbow and two straight tangent pipes. The simplified analysis is found to considerably overestimate the measured results, especially for the case of creep behavior. The correlation of detailed analysis predictions with measured results is satisfactory for the elastic-plastic behavior of the structure, and inconclusive for the creep behavior, since the creep predictions are based on a commonly used creep law rather than on the actual (but unmeasured) creep properties. The paper also shows that predictions of creep deformation obtained from the relatively inexpensive time-independent isochronous method of analysis agree well with results given by a “complete” and more costly time-dependent creep analysis.