PSI - Issue 84

Allan Larsen et al. / Procedia Structural Integrity 84 (2026) 1103–1110

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anchor plates by means of fork socket / eye plate connections. A typical hanger arrangement featuring a ø 70 mm locked coil cable sheathed by a 7 mm HDPE coating is shown in Fig. 1.

Hanger cross section

Hanger general arrangement

Hanger socket

Fig. 1. General arrangement of hangers, Hålogaland bridge, Norway.

While the older types of stranded wire hangers do not appear to be particularly sensitive to wind effects, wind induced vibrations of the newer types of hangers are reported on a regular basis raising questions to structural fatigue and concern with the public crossing the bridges, Inoue et al (2017). A way of mitigating suspension bridge hanger vibrations is by adding mechanical damping in the form of mechanical resonant dampers (Stockbridge dampers) or hydraulic dampers, Inoue (2021). Stockbridge dampers are commonplace devices in power supply engineering for mitigation of wind induced vibration of overhead power lines, Wolf et al (2008). This paper presents an overview of the two most common aerodynamic mechanisms responsible for the excitation of vibrations of single contemporary suspension bridge hanger cables. The most common form of aerodynamic vibrations is vortex induced vibrations (VIV) also referred to as aeolian vibrations (IEEE 2015). Cross wind galloping vibrations are sometimes observed for rainy or snowy conditions in combination with wind. A third form of vibrations referred to as wake galloping may be observed on bridges where hanger cables are grouped in pairs or are sitting in the wake of the towers. These situations are very particular to a given bridge design or site and are not discussed further in this presentation. Vibrations of hanger cables result when the energy transferred to the cable by exterior sources such as traffic or the wind exceeds the dissipation capacity of the cable. The dissipation capacity referred to as structural damping is of internal metallurgical nature, friction at the anchorages and fretting between the individual wire strands of the cable. Foti (2018) has demonstrated that the damping due to fretting is a very important for energy dissipation in helical