ASSESSMENT OF WIND-INDUCED RESPONSE AND DRIVABILITY OF THE CONFEDERATION BRIDGE

The Confederation Bridge is a 13 km long precast concrete structure, constructed between 1993 and 1997, comprised of 43 - 250 m spans in an alternating rigid frame/cantilevered drop-in span arrangement. Wind studies were conducted in the early \u2790s at the Boundary Layer Wind Tunnel Laboratory to predict the design wind speed and associated design wind loads for the bridge. The dynamic wind loads were developed using full-aeroelastic model test data for the first time. The bridge owners implemented a comprehensive bridge monitoring programme to document the interaction of the bridge with its environment by installing a complex instrumentation system along a one kilometre section of the bridge in 1998. The research reported in this thesis analyses this dataset, augmenting it as necessary with data from other instrumentation on the bridge, to determine the accuracy of the original design wind speeds and wind loads predicted in 1994. Based on ten years of wind records it is shown that the design ten-minute mean wind speed with a 100-year return period is within 1.5% of the 1994 design value, and that the bridge has been subjected to this design event once during the November 7, 2001 storm. The dynamic load effects predicted using the 1994 loads adjusted for the actual damping of the prototype are 6% and 28-58% greater than those determined from the on­ site monitoring data for the transverse and vertical effects, respectively. The research therefore validates the aerodynamic model-based methodology developed in 1994 which can be used to derive wind loads using on-site monitoring or full-aeroelastic model test data. A second research topic is the challenge of driving high lightly loaded vehicles across the bridge during wind storms. Data are presented from an instrumented bus and truck-trailer that were driven repeatedly across the bridge during a severe windstorm. The drivers’ perceptions of the severity of the wind effect on the control of the vehicle are strongly correlated to the transverse accelerations that they are subjected to, which increase with increasing vehicle speed. Current operating procedures that restrict high­ sided vehicles from crossing the bridge when the wind speed exceeds 70 km/h in any direction were not perceived to be unsafe by either participating driver. The response of a bus and a truck-trailer crossing the bridge under wind conditions are different: the truck- trailer seems to be much more susceptible to roll-over than the bus