Equivalent fundamental period of bridge piers on caisson foundations from dynamic centrifuge testing: Fid-Bau Portal

Equivalent fundamental period of bridge piers on caisson foundations from dynamic centrifuge testing

Gaudio, Domenico / Madabhushi, Gopal S.P. / Rampello, Sebastiano / Viggiani, Giulia M.B.

Abstract Dynamic soil-structure interaction is typically decomposed in kinematic and inertial effects. Inertial interaction generally results in an increase in the fundamental period and damping of the system, which, for slender structures, corresponds to a decrease of the inertial forces transmitted to the superstructure. Relations to estimate the period increase are mainly available in the literature for shallow foundations. In this paper, the fundamental period of bridge piers on compliant caisson foundations was obtained from dynamic centrifuge tests. A rigid and a flexible bridge pier were subjected to trains of sinusoidal waves and real ground motions. The interpretation of the experimental results permitted to (i) evaluate the increase of period with respect to fixed-base conditions; (ii) assess the dependency of the compliant-base period on the motion intensity. The second aspect sheds light on the role played by non-linearity of soil behaviour and emphasises the importance of performing preliminary soil response analyses.

Highlights • Inertial interaction results in an increase of the system fundamental period. • Dynamic centrifuge tests of bridge piers on caisson foundations were performed. • The increase of the fundamental period with respect to the fixed-base was evaluated. • The dependency of the fundamental period on the earthquake intensity was assessed. • The results emphasises the need of performing preliminary soil response analyses.