Abstract: Predicting the collapse potential of a structure during
earthquakes is an important issue in earthquake engineering. Many
researchers proposed different methods to assess the collapse
potential of structures under the effect of strong ground motions.
However most of them did not consider degradation and softening
effect in hysteretic behavior. In this study, collapse potential of
SDOF systems caused by dynamic instability with stiffness and
strength degradation has been investigated. An equation was
proposed for the estimation of collapse period of SDOF system which
is a limit value of period for dynamic instability. If period of the
considered SDOF system is shorter than the collapse period then the
relevant system exhibits dynamic instability and collapse occurs.