Effects of Plasticity on Dynamic Response of Piping Structures

The analysis of elastoplastic structures under a combination of static and dynamic loads is examined. It is shown that under the hypothesis of a ductile behavior, progressive distortion is the leading failure mechanism. Procedures are described to compute: (a) the equivalent damping due to hysteretic losses; (b) frequency shifting due to structural softening in the plastic fields; (c) ductility effects on dynamic loads; and (d) ratcheting due to a combination of static and dynamic loads.