An Offline Real-Time Substructure Shake Table Test Method for Pile-Supported Wharves

Pile-supported wharves (PSW) are vital for port infrastructure, making seismic resilience essential for regional economic stability. Shake table testing is fundamental to evaluating PSW seismic performance, with large-scale specimens required to accurately replicate prototype pile materials and pile-deck connections. However, the use of heavy-load soil boxes consumes much of the table's load capacity, limiting high-level PGA seismic excitation. Additionally, the scaling effects of the soil complicate the accurate simulation of pile-soil interactions. To address this, an offline real-time substructure shake table testing (offline RSST) is proposed, eliminating the need for the soil box and enabling high-level PGA excitation for large-scale specimens. In this method, the PSW is divided at the soil surface; the foundation is modeled as a simplified amplifier providing lateral stiffness, and together with the superstructure forms the wharf substructure (WS). The input to the WS is adjusted via an offline FFT/IFFT procedure to replicate the prototype's response. Numerical validation for a batter-pile PSW showed frequency domain errors of 3.1% in deck acceleration and 1.4% in batter-pile axial force. Subsequent 1:10 large-scale shake table tests further validated the method, demonstrating accurate replication of key responses under multi-level excitation and providing a practical framework for seismic performance assessment of PSW.