Incorporating the influence of duration on dynamic deformation capacity in structural design and assessment

The dynamic deformation capacity of a structure is the peak storey drift ratio it can safely withstand without collapsing due to dynamic instability. In a previous study, the authors developed a robust procedure to compute this quantity by conducting incremental dynamic analysis and demonstrated that structures, on average, possess lower dynamic deformation capacities under longer duration ground motions. This paper proposes a method to explicitly consider this effect of ground motion duration in seismic assessment of existing buildings. Preliminary results indicate that the dynamic deformation capacity of a structure at short durations compares well with its static deformation capacity computed via nonlinear static pushover analysis. These results are used to develop a relationship to adjust the static deformation capacity of a reinforced concrete structure based on the mean duration of anticipated ground motions