A model for the cyclic behaviour of steel under earthquake conditions

During the mid 1990s earthquakes in Northridge, California, and Kobe, Japan, illustrated a lack of understanding of the behaviour of structural steels exposed to seismic loads. Under this type of load regime, structural steel members are subjected to fully plastic load cycles and unexpectedly brittle failures resulted. This paper presents a simple, yet powerful, method for predicting the accumulation of damage in a steel element, based on its toughness. In addition the damage parameter chosen provides an accurate prediction of when failure of the element can be expected to occur. The damage accumulation model developed allows for the deconvolution of complex load histories, such as could be expected to occur during a seismic event, in a systematic, stepwise manner. This approach is ideally suited to automation and could readily be implemented into a finite element model.