Experimental Evaluation of Coupled Seismic–Wind Load Effects on the Antenna Mast Atop Super High-Rise Structures via Hybrid Shake Table–Wind Tunnel Tests

Antenna masts atop super high-rise structures (AM–SHRSs) are highly slender and flexible appendage systems characterized by pronounced stiffness discontinuities, making them particularly susceptible to dynamic amplification under coupled seismic–wind loading. This study investigates the dynamic response of the AM–SHRS under coupled seismic–wind loading, with particular emphasis on the effects of load intensity and directionality. A hybrid shake table–wind tunnel platform was developed to enable simultaneous bidirectional seismic and turbulent wind excitation. A 1:40 scaled model of the upper portion of a 430 m prototype structure was constructed to enhance response observability. To capture the long-period behavior of SHRSs, near-field (NF) pulse-like and far-field (FF) long-period ground motions were selected. The test matrix included nine intensity scenarios and nine directional combinations to systematically evaluate the influence of seismic incident angle (SIA) and wind attack angle (WAA). The results demonstrate that coupled excitations amplify structural displacement responses beyond those caused by individual hazard, with the effect diminishing at higher seismic intensities. Variations in SIA and WAA significantly influence the coupled response; NF excitations exhibit stronger directional sensitivity while FF excitations dominate in response magnitude. Furthermore, asynchronous phase interactions between seismic and wind inputs produce non-monotonic trends, emphasizing the necessity of considering dynamic coupling mechanisms rather than relying solely on peak demand superposition. These findings underscore the importance of considering both intensity and directional effects in multi-hazard design, and highlight the value of integrated experimental platforms for assessing the performance of AM–SHRSs under concurrent extreme events.