Flutter analysis of long-span suspension bridges: the case-study of the Messina Strait project

The construction of a permanent link over the Messina Strait has aways been considered a great undertaking, due to challenging environmental conditions such as the depth of water, strong sea current, intense wind, and seismic activities. The bridge’s design and feasibility debate began several decades ago, culminating in 1992, with the approval of the world’s longest suspension bridge project, featuring a main span of 3300m. This thesis focuses on one of the most dangerous phenomena that could occur in suspension bridges, i.e. flutter instability. The analysis aims to investigate the behaviour of the Messina Strait Bridge under wind loads, utilizing both numerical and analytical approaches. The first part provides a brief overview of the evolutionary process of suspension bridges. Subsequently, the development of the Messina Strait Bridge project is presented, from the 1970s up to the most recent updates. Furthermore, the effects of wind action on long-span suspension bridges are described. Lastly, previous studies conducted by different researchers on this project are reported, and their results will be compared to the results obtained in this thesis. The second part of this thesis focuses on the various models developed, from a simpler model of the main span only to the complete model of the entire bridge. Afterwards, the numerical methods adopted in this study are introduced and the flutter analysis is carried out, using both Matlab and Ansys software, in order to determine the critical flutter velocity of the wind, that initiates instability, and the flutter frequency. In conclusion, the results obtained from the two different methods employed in this study exhibit strong agreement with each other and align with the results obtained by other researchers.