Abstract
This investigation deals with the rocking response of a rigid block subjected to 1-dimensional harmonic excitations with minute changes of the system parameters, such as the frictional coefficient, and the excitation parameters. 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 response of the block is 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 should be considered when seismic stable condition of block structures.
