The variability of deformation demand with ground motion intensity

The use of Nonlinear Dynamic Analyses is coupled to the demands produced by earthquakes of different intensities. The uncertainties associated with the demands are highly dependent on the variable adopted as the intensity measure (IM). This generates the need to compare different IMs and in particular the dispersion of the demand measure in relation to each IM. For this purpose correlations between maximum inter-story drift demand of nine reinforced concrete Multiple Degree of Freedom tridimensional structures and a number of widely used ground motion intensity parameters have been investigated. To determine the optimum parameter to be used as the IM, two additional intensity parameters are analyzed, the spectral acceleration corresponding to the cracked and non-linear period of each structure, Sa(Tcrack) and Sa(T∗)Sa(T∗), respectively. The results showed that these two IMs have the best correlation with the deformation demand and their use produces a lower variability of structural response.

► Nine reinforced concrete structures are subjected to different sets of records.
► From each record seven different intensity parameters are obtained.
► For each structure and record the maximum inter-story drift demand is obtained.
► Correlations between the drift demands and the intensity parameters are examined.
► Sa(Tcrack) and Sa(T∗)Sa(T∗) produce the lowest variability of structural response.