Smooth-rocking oscillator under natural accelerograms

Abstract

Following the work by Psycharis [1], in this paper we study the dynamic behavior of a rocking block resting on an elastic Winkler-type foundation for the out-of-plane seismic assessment of masonry walls. The equations of motion are derived and implemented for the simple smooth-rocking block and the calibration of the Winkler-type foundation stiffness is carried out according to the experimental results available in the literature. The dynamic response under natural seismic records is evaluated and the effect of the stiffness on the overall response is analyzed for different natural accelerograms. Both demand and capacity are calculated with reference to the kinetic and potential energies of the system and different intensity measures are considered with the aim of identifying the most representative one for the rocking motion. Finally, a comparison between non-linear time history analyses and a possible energy-based approach is discussed.