Prof Santiago Hernandez from the University of La Coruña, Spain, visited Ashurst Lodge and gave a lecture on the Sensitivity Analysis and computer assessment of the aero-elastic behaviour of the proposed Messina Bridge. This is an interesting and exciting engineering project which will link continental Italy with Sicily. This idea has been proposed for a long time and is finally coming to fruition. The total length of the bridge will be approximately 3km and the main suspended span will be 2km long.

The University of La Coruña has been actively involved in studying the aero-elastic response of the proposed bridge, working in conjunction with one of the major contractors. Experimental testing in wind tunnels has been followed by computer based aero-elastic analysis.

The approach followed by the La Coruña Group has been to test a typical section of the bridge deck and determine its aero-elastic behaviour. The resulting co-efficients are then used to model the whole bridge. This has the added advantage of being able to use comparatively small wind tunnel, rather than one in which the whole structure could be tested. Experiments produce 18 co-efficients representing the aero-elastic stiffness and damping of the typical structural element.

The study laid particular emphasis on the determination of flutter characteristics which were the main reason behind the classical Tacoma bridge collapse.

Once the aero-elastic analysis has been completed, the sensitivity of the response can be studied. Extensive use was made of computer animation to fully understand the behaviour of the bridge.

The lecture was very well received and a lively discussion ensued.