DESIGN ASPECTS OF TUNED MASS DAMPERS FOR THE GREAT-BELT-EAST-BRIDGE APPROACH SPANS

The Great Belt East Bridge includes two approach bridges with steel girders designed as multi-span beams. The continuous long span design has lead to flexible structures characterized by closely spaced eigenfrequencies for vertical vibration modes. Wind tunnel tests including section and full-bridge aeroelastic models have confirmed that the approach bridge structures are prone to vortex-shedding excitation at wind speeds encountered regularly at the bridge site. The present paper discusses design aspects of tuned mass dampers (TMDs) for control of wind induced vibrations. A key point is the introduction of a new analysis model for assessment of TMD characteristics which acknowledges the non-linear motion dependent response observed in wind tunnel tests. Application of this model in design yields smaller TMD masses than obtained from conventional linear theory.