Rocking of rigid block under minute fluctuation of system parameter (1st report, minute fluctuation of friction coefficients)

This investigation deals with the rocking response of a rigid block subjected to 1 dimensional harmonic excitations with the minute changes of the system parameters, such as the frictional coefficient. This paper is part one of the examination about the effects by those minute changes and is related with the minute change of friction coefficients. The numerical analysis program is developed to solve the nonlinear equations of motion governing the rocking motion of a rigid block subjected to horizontal base excitation. Natural change of the frictional coefficient is realized by the random numbers with normal probability distribution. The analytical results showed that the rocking responses are very sensitive to small changes of the friction condition between the block and the base and their effect is also large. The minute change of the friction coefficients makes the rocking response unstable and the distribution shape of rocking response change massively. Those effects by the dynamic change of the friction coefficients become a testimony of the non-reappearance on the experimental rocking responses.