Behaviour of Embedded Beam Formulations under Dynamic Loading

Fully-coupled dynamic finite element analyses (FEA) of pile foundation structures are computationally demanding; hence, they are rarely performed in practice. Due to their exceptional ability to circumvent this obstacle, dimensionally reduced beam-type-elements (BTE), such as embedded beam formulations (EBF), have gained popularity in dynamic FEA of related problems. The current engineering approach assumes a high level of compliance in the predicted dynamic response across different pile modelling techniques. However, static FEA have shown that this assumption is not generally warranted, primarily due to limitations of the line-to-volume coupling scheme employed in classical BTE. This raises an obvious questions about their general applicability to dynamic FEA of pile foundation structures, which generally require a realistic representation of dynamic soil-structure interaction. Subsequently, comparative dynamic FEA are carried out considering different embedded beam formulations. The credibility of results is numerically validated based on direct comparisons with the well-accepted standard FE approach. In this regard, EBF capture the free vibration behaviour with high accuracy. Special care must be taken when using EBF for the prediction of kinematic amplification ratios close to resonance.