evaluation of structure frequency on the dynamic response of piled raft foundations

This study examines the impact of structural frequency under various input excitations on the dynamic behavior of a piled raft (pr) foundation embedded in a dry sand layer. numerical modeling using the finite element method was evaluated by experimental results from centrifuge test. the findings reveal that the structure's natural frequency, affected by the dynamic characteristics of both the soil and the foundation, is significantly lower than that of the fixed-base condition. however, the structure's frequency changes are independent of the excitation dominant frequency. furthermore, as the structure's natural frequency rises, the disparity between the fixed-base condition and the foundation-inclusive scenario becomes increasingly pronounced. these changes significantly affect the whole dynamic system responses, precisely the maximum bending moment along the piles. it highlights the importance of considering the soil-structure interaction in the design process. additionally, when the frequency of the input excitation closely aligns with the system's natural frequency, it induces the most significant dynamic responses in the soil, pile, raft, and structure. consequently, relying solely on fixed-based methods in design can lead to unrealistic and potentially unsafe technical decisions.