Real‐time hybrid simulation for fluid‐structure interaction: Structures under seismic and hydrodynamic forces

Abstract A new real‐time hybrid simulation (RTHS) scheme for fluid‐structure interaction to investigate structures subjected to seismic and hydrodynamic forces is proposed. In traditional testing of underwater structures, the conflict between scaled specimen and unscaled water makes only partial similarity laws can be satisfied. In the proposed scheme, the hydrodynamic force is regarded as physical substructure (PS) and the target structure under earthquake is regarded as numerical substructure (NS). In RTHS, the deformation and displacement of NS are calculated and sent to the controller of loading system. Loading system deforms and drives the “skin” that makes the state of “skin” identical to that of NS, and then the hydrodynamic force on structure is measured and fed back to NS by sensors. “Skin” is a shell whose shape is consistent with target structure and sensors are arranged on the “skin” to measure the hydrodynamic force. Due to NS is simulated and PS is experimentally measured, only the similarity laws of hydrodynamic force should be satisfied in experiment, and the conflict of traditional testing can be avoided. For verifying the proposed scheme, five evaluation indexes proposed by a benchmark problem of RTHS and a modified index are used to quantitatively analyze the experimental results. The results indicate that the response of underwater structures under an earthquake can be accurately obtained by proposed RTHS scheme. Moreover, the proposed scheme is not only applicable to still water but also has the potential to be applied to the environment of waves and currents.