Field experiments for monitoring the dynamic soil-structure-foundation response of a bridge-pier model structure at a test site

Summary results from a series of field experiments at a test site in Greece are presented, involving an in situ instrumented bridge-pier model built on realistic foundation conditions, to study the dynamic behavior of structure-foundation-soil system. It was attempted to link the variation of its dynamic characteristics to certain changes in its structural system, including the development of structural damage. This measured response was next utilized to validate numerical tools capable of predicting influences arising from such structural changes as well as from soil-foundation interaction. This bridge-pier model was supported on soft soil deposits allowing the study of structure-foundation-soil interaction effects during low-to-medium intensity artificial excitations. The in situ experiments provided measurements that were used to verify fundamental analytical solutions for soil-structure interaction. They were also used to validate numerical simulations that were developed to predict the response of the studied structure and thus, back-evaluate modeling assumptions. The obtained accuracy of the numerical predictions must be partly attributed to sound knowledge of the mechanical properties of the pier model and of the soil, not necessarily the case in all practical applications. It is evident that more complex finite-element models can improve the quality of the prediction only in cases where their parameters can be defined equally well. A special study further focused on the radiation of the waves generated by the vibration of the bridge-pier model through the soil medium. It is deemed that this comprehensive experimental investigation of soil-structure interaction provides measurements of the system response and enhances our understanding of the physical phenomenon as a whole.