The effect of friction on ground excited sliding elastic systems

A sliding elastic system with two masses, which are connected to each other by a spring and a viscous damper in parallel, is examined in this investigation in terms of its response to various forms of ground motion as a funtion of the friction factor and the ratio of the masses. The sliding mass is damped by Coulomb damping while the other mass is damped only by viscous damping. The response of the system to the half-cycle velocity pulse, half-cycle displacement pulse, and the full-cycle displacement pulse is examined. Sliding reduces the response especially in the medium and high frequency regions for all pulses. This reduction between the maximum response values of the non-sliding spectrum and FF .2 spectrum for m/i 1. is 7.4%, 53.4%, and 58.3% for half-cycle velocity, half-cycle displacement, and full-cycle displacement pulses. The general appearance of the spectra, spectral maxima, and upper envelopes for different pulses are similar although there are some numerical differences in these quantities due to the different shapes of the input motions. The results of this investigation show the characteristics of the system to ground excitations provided the natural frequencies, sliding forces, damping factors, and the masses are known