Methods for estimating strain in structures - conditions and definitions

Abstract Analyses of the impact of actual earthquakes on industrial plants and experimental investigations simulating earthquakes and pressure surges show that loads can be sustained without damage, which are according to the existing design rules far beyond the allowable limit and which cannot be calculated realistically assuming linear-elastic material behaviour according to plastic deformation. To rely on the existing capability to absorb large amounts of energy, it is necessary to have models for describing their behaviour in the plastic range taking into account the plastic deformation volume and the strain values reached. Especially for the calculation of piping systems under loads with a small probability of occurrence, the main parameters for describing the energy dissipated and the additional strain in comparison to the strain in a straight pipe are described, independent of the calculation method used (simplified or elasto-plastic time integration). In addition, strain categories and the individual strain category responsible for the integrity of the overall system are defined.