A Case Study on Response Characteristics of Large Steel Frame Support Structures Under the Combined Action of Earthquake and Wind Loads, Considering Shielding Effects

Large steel frame support structures may encounter multiple-hazard coupling effects, such as earthquakes and wind loads, during their service period, and their combined damage effects are often significantly greater than those under single-hazard conditions. This study focuses on a single case example of large steel frame support structures, adopts a one-way CFD (Computational Fluid Dynamics)-to-structure loading analysis method to quantify the distribution of wind drag coefficients influenced under shielding effects, and reveals the response amplification and transition behavior under earthquake–wind load coupling effects through a systematic parametric analysis. The results demonstrate that within the simulated wind speed range (10–30 m/s), the drag coefficient of the structure is insensitive to the Reynolds number. The drag coefficient of the first row of members remains stable at approximately 1.25, whereas those of the second and subsequent rows are concentrated in the 0.6–0.8 range and decrease progressively along the wind direction. This pattern challenges the conventional design assumption of using a unified drag coefficient. Based on the analyzed cases, under earthquake–wind coupling effects, the structural amplitude amplification effect demonstrates significant load-dominant transition characteristics—when the earthquake acceleration is low (0.05 g), the wind load-induced amplitude amplification effect is pronounced, reaching 206.3%. As the earthquake intensity increases, the amplification effect stabilizes at approximately 9%. This study identifies structural drag coefficients for considering shielding effects, reveals the coupling mechanism between earthquakes and wind loads, and provides theoretical support for the multihazard performance-based design of temporary large-scale spatial structures. It should be noted that the findings and the proposed load-dominance transition characteristics are primarily applicable to temporary large-scale spatial frame structures operating within a service wind speed range of 10 to 30 m/s.