Each civil engineering structure inevitably passes the
phase of low cycle fatigue during strong impact loads of the earthquake, and
light structures often fail due to loss of local or global stability (local
buckling or deflection of structural components.
It is practically impossible to understand the behaviour
of buildings subjected to seismic loads without base knowledge of behaviour of
structural components during low-cycle fatigue process as well as the global
stability of the structures during all phases of earthquake action.
Low cycle fatigue is examined theoretically and
experimentally, using damage mechanics concept. Special attention is paid to
ultra low cycle fatigue, in the sense Dufailly-Lemaitre. The theory is applied
on dampers for strengthening structures damaged in the earthquake. Theoretical
considerations are also experimentally checked.
Keywords: hysteresis, damage, damper, structural integrity