Equivalent ductility factors, taking into account low-cycle fatigue

摘要: During strong earthquakes, the deformation capacity of structures is reduced due to cumulative damage caused by cyclic load reversals. In paper, equivalent (reduced) ductility factors have been proposed, which take into account this effect. They are based on different failure hypotheses. Ductility reduction low-cycle fatigue controlled a dimensionless parameter γ, function dissipated hysteretic energy, maximum displacement and natural frequency structural system, has proved be relatively stable quantity in whole period range. If approximate values for γ used, determination very simple, thus appropriate design purposes. The formulae include indices, permit designer choose acceptable level explicitly. As an example, used construct inelastic acceleration spectra, proportional strength demand, El Centro 1940 SOOE record. results compared with ‘exact’ spectra obtained non-linear dynamic analysis.