Reduction of Large Seismic Deformations using Elasto-plastic Passive Energy Dissipaters

Abstract

The design of supporting systems for pipelines carrying highly toxic or radioactive liquids at very high temperature, is an important issue in the safety aspect for a nuclear power installation. These pipeline systems are normally designed to be held rigid by conventional snubber supports for protection from earthquake. The pipeline system design must balance the seismic deformations and other deformations due to thermal effect. A rigid pipeline system using conventional snubber supports always leads to an increase in thermal stresses, hence a rational seismic design for pipeline supporting systems becomes essential. Contrary to this rigid design, it is possible to design a flexible pipeline system and to decrease the seismic response by increasing the damping using passive energy absorbing (PEA) element, which dissipates vibration energy. An X-shaped or a hourglass-shaped metal element is a classic example of elasto-plastic passive energy absorber of metallic yielding type. The inherent ductile property of metals like steel, which undergoes stable energy dissipation in the plastic region, is made use of in achieving energy loss. This paper presents the experimental and analytical studies carried out on yielding-type elasto-plastic PEA elements to be used in a passive energy dissipating device for the control of large seismic deformations of pipelines subjected to earthquake loading.