Large Span Composite Beams with Integrated Dynamic Absorbers

This paper describes one solution to the vibration problem of long span composite beams by means of integrated dynamic absorbers. These were used in the floor construction of the new exhibition halls in Berlin. The stiff and heavy composite beams used in the original design with a natural frequency of 5 Hz were replaced by composite trusses with reduced weight and a natural frequency of less than 4 Hz together with integrated damper systems. Part of the bottom chord of the truss is a tension bar only fixed at the ends and vertically suspended by elastomeric springs. The tension bar stiffens the system and works additionally as a damper [1]. This method of construction means the weight of the beams can be reduced to 60 % of the comparable beam without dampers — a significant reduction in costs. The effects have been verified in tests. In addition, potentially interesting structures with integrated damper systems, used for instance in sports halls, are also described.