The main objective of the project was to increase roof-covered seating capacity for big events, in preparation for the World Athletics games in 2005. The new roof had to fit the old structure without substantial modification, since the stadium is one of the Finnish national architectural landmarks.
The large roof, which measures 98 x 39m, has a wing-like flat design. It is supported eccentrically by underneath columns. The longest cantilever measures 26m.
WSP provided wind-engineering services for the roof with analytical assessments and wind tunnel testing. Results were transmitted to structural engineers and architect for finalizing the design. This project presented some peculiar challenges:
- vibration-prone wing-like shape
- low dead load
- wake buffeting due to existing stadium structures
- interaction of wind and snow load
- wind-induced fatigue.
The design has performed as expected. Vibration amplitudes are small enough not to cause any visual problems to spectators. First testing of this realized already during the games in 2005, when bad weather and strong thunderstorm hit the fully crowded stadium.
In the project WSP developed advanced technologies, like:
- application of aero-elastic wind tunnel testing to the roof-type structure
- stress cycle counting using Rainflow method, wind-tunnel testing and local long-term wind statistics
- automated milling of base wind tunnel model using 3D CAD/CAM model.
The main benefit for the client in using WSP’s services were:
- preservation of the original architecture, which has obtained many awards since the opening of the new stadium
- rigorous assessment of wind loads and vibration levels, which during the design process has lead to strengthening of the structure, without any increase in the construction costs.