PSI - Issue 84

Gian Felice Giaccu et al. / Procedia Structural Integrity 84 (2026) 1055–1062

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1. Introduction In recent decades, significant progress has been achieved in the design of long-span cable-supported bridges (Ding et al., 2023). As the demand for ever greater spans increases, the development of innovative solutions has become essential to enhance wind-resistant performance. The proposed Messina Strait crossing, intended to be the world’s longest suspension bridge, exemplifies both the ambition and the complexity associated with super long-span structures. Challenges linked to seismicity, deep-water foundations, strong marine currents, and severe wind conditions have contributed to recurring delays and uncertainties in its realization, despite the renewed interest generated by the recent preliminary approval issued by the Italian government. Wind effects on bridges of this scale have been widely studied through sectional model investigations [e.g., (Diana et al., 2003; Diana et al., 2010)] and analyses of static and dynamic wind loads, including flutter and vortex-induced vibrations. These studies have substantially advanced the understanding of wind–structure interactions and have informed several design methodologies for long-span bridge decks. Flutter instability remains a critical design concern, emerging when wind speeds exceed a threshold at which vertical and torsional motions become coupled and diverge (Scanlan and Tomko, 1971). Prediction of this phenomenon typically relies on the characterization of motion-induced aerodynamic forces through the Scanlan derivatives (SDs), which model the unsteady aeroelastic loading on the deck (Scanlan and Tomko, 1971). New experimental results, presented herein, will show that the gyroscopic stabilizer can substantially increase the critical wind speed of the tested bridge deck model. The device proves to be effective even with a relatively small mass moment of inertia when compared to the modal properties of the deck. Tests also demonstrate that the stabilizer maintains its performance under varying dynamic conditions, confirming its capability to suppress flutter once oscillations develop. Furthermore, the experiments highlight the device’s robustness with respect to variations in the deck's aeroelastic response. Overall, the findings provide valuable evidence of the stabilizer’s potential as a practical solution for enhancing the aeroelastic stability of long-span bridges. 2. Modeling the gyroscopic stabilizer This section summarizes the derivation of a generalized scale model used to analyze the vibrations of the Golden Gate Bridge deck section (Jain, 1996; Jain et al., 1996; Jain et al., 1998), used as a testbed structure, and its interaction with an internal gyroscopic device. The numerical model reproduces the primary bending and torsional modes relevant to flutter and incorporates a lumped representation of the gyroscopic system, enabling investigation of the coupled aeroelastic response under simulated wind conditions. Figure 1 shows the schematic of the rotating mass used in both the numerical model and the wind tunnel setup.

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(a) (b) Fig. 1. Gyroscopic model, set on the Golden Gate Bridge model (illustrative example): (a) Schematics of rotating mass (and local reference axes), (b) 3D lateral view with aeroelastic loads The gyroscopic device is modelled as a lumped-mass, lumped-inertia system with two rotational DOFs (D'Eleuterio, 1986) in Fig. 1(b): torsion about the deck’s horizontal axis and rotation about the vertical axis, α in Fig.