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This study deals with the seismic fragility of elastic structural systems equipped with single concave sliding (friction pendulum system (FPS)) isolators considering different soil conditions. The behavior of these systems is analyzed by employing a two-degree-of-freedom model, whereas the FPS response is described by means of a velocity-dependent model. The uncertainty in the seismic inputs is taken into account by considering artificial seismic excitations modelled as timemodulated filtered Gaussian white noise random processes of different intensity within the power spectral density method. In particular, the filter parameters, which control the frequency content of the random excitations, are calibrated to describe stiff, medium and soft soil conditions. The sliding friction coefficient at large velocity is also considered as a random variable modelled through a uniform probability density function. Incremental dynamic analyses are developed in order to evaluate the probabilities of exceeding different limit states related to both the reinforced concrete (RC) superstructure and isolation level, defining the seismic fragility curves within an extensive parametric study carried out for different structural system properties and soil conditions. The abovementioned seismic fragility curves are useful to evaluate the seismic reliability of base-isolated elastic systems equipped with FPS and located in any site for any soil condition. [ABSTRACT FROM AUTHOR]

Systematic differences in the duration and frequency content of ground motions from the hanging wall and footwall during the 2008 Wenchuan earthquake are investigated, focusing on the influence of these differences on structural input energy based on the elastic and inelastic energy responses of structures. A comparison of the input energy spectra between the hanging wall and the footwall reveal that the structural input energy on the hanging wall is not amplified due to the short duration and low peak ground velocity to acceleration ratio ( V/A). However, the larger demand of structural input energy on the footwall in the range of medium and long periods is observed and the demand increases up to 50% relative to the average level of structural input energy for rupture distances larger than 30 km. The importance of considering the footwall effect on structural input energy when comparing ground motions in the range of medium and long periods is recognized. [ABSTRACT FROM AUTHOR]