Wind Vibration Tests

The Second Severn Crossing

A new bridge, called the Second Severn Crossing, was completed across the river Severn in 1996
(Where is it?).

The central part of the bridge across the deepest part of the river is a cable stayed bridge. This section of the bridge is approached by viaducts from both banks of the river. The EERC recorded and studied the vibrations of the cable stayed bridge in the wind, during and after construction (Explain).

They used accelerometers to measure the vibrations of the bridge deck, the towers and the cables (Show Me).

The movement of the bridge was also recorded using a video camera which tracked the movement of targets fixed to the bridge (Show Me).

Electrical signals from the accelerometers and the video camera were carried along cables back to the recording equipment. The monitoring and recording of the vibrations were controlled by computer. (Show Me)

The equipment was left on the bridge for many months. It was set up to record vibrations only when the wind went above a particular speed. The wind speed was measured with another electronic instrument called an anemometer.