Use of Ricker wavelet ground motions as an alternative to push-over testing

When conducting studies of seismic soil-structure interaction, it is useful to be able to define the pseudo-static 'push-over' response of the structure under static horizontal loads representing the structural inertia. Normally, this would require separate centrifuge experiments with horizontal actuators attached. This paper describes an alternative procedure, using a specific type of ground motion (a Ricker wavelet) to obtain the push-over response, thereby allowing both this and the response to conventional earthquake shaking to be determined using the same (earthquake) actuator. Application of this technique to a 1: 50 scale model highway bridge pier with two different shallow foundations is presented. The moment rotation ('backbone') behaviour of the footings was accurately determined to large rotations, as verified though independent 3-D non-linear finite element modelling. Ricker wavelet ground motions are therefore shown to be a useful tool for the identification of push-over system behaviour without requiring additional actuators.