Real-Time Hybrid Test Development and Application in Soil–Structure Interaction Systems

Real-time hybrid testing is an efficient testing technique that combines physical testing with numerical calculations to jointly evaluate the performance of complex structures under different external excitations. This study conducted a quantitative bibliometric analysis of 121 RTHT articles published between 1992 and 2025. The survey revealed that only 8% of all test applications addressed soil–structure interaction systems, merely 3% employed finite element models exceeding 10,000 DOFs, and more than 90% of the interface equations were still based on lumped mass assumptions. An RTHT framework based on the branch modal method was proposed to overcome these limitations. Within this framework, the numerical soil substructure was reduced from thousands of DOFs to approximately one hundred DOFs, with a verified peak acceleration error of below 7%. This approach offers a practical reference for real-time hybrid testing of complex systems.