Evaluation of Nonlinear Response of Block Foundation Subjected to Vertical Vibration

Dynamic tests subjected to vertical vibration were conducted on a small-scale block footing of aspect ratio (L/B = 1.0) and depth of 0.5 m resting on the ground surface. The tests were conducted under a static load of (WS) 6.6 kN to determine the dynamic amplitude responses for different excitation intensities. The theory of nonlinear vibrations was used to back-calculate the dynamic nonlinear responses from the experimental response curves. The nonlinear responses indicate the disparity in the undamped natural frequencies with vertical translational amplitudes. It was observed that the approach well anticipates the nonlinear characteristics of the frequency–amplitude responses of the soil-foundation machine oscillator system.