Experimental investigation on vortex-induced vibrations of a single-box girder with extended cantilevers and its mitigation strategies

This study experimentally investigates the vortex-induced vibrations (VIVs) of a single-box girder with long cantilevers, focusing on the impact of handrail modifications on mitigating VIV amplitudes. The results highlight that the VIVs of the bridge occur in both vertical bending and torsion, with the VIV peaks exceeding the permissible values in both degrees of freedom. The analysis reveals that both the outer handrails and maintenance rails influence the VIV performance, with the outer handrails playing a dominant role. Smoke flow visualization provides significant insights, demonstrating that large amplitude VIVs are closely associated with the curbstone and bottom porosity of the outer handrails. Modifications to the outer handrails, particularly the streamlining of the curbstone's aerodynamic shape and improvements to the bottom porosity, are found to significantly reduce the VIV amplitudes in both vertical bending and torsion. The findings suggest that modifying the outer handrails could be an effective approach to controlling VIVs in similar bridge structures.