The dynamic analysis of suspension bridges with geometrically nonlinearity and elastic foundation analogy

SUMMARY Suspension bridges are important structures in engineering. They are built for both accrossing the long spans (>550m) and giving to rise to the usage of domains under the bridge. Analysis of suspension bridges must be done on the best possible analytical model since deck, towers and cables show different pattern of motion. Therefore, analysis of suspension bridges are carried out by using geometrically nonlinearity adopted in the mathematical model. In this study, the Bosporus Suspension Bridge is selected as mathematical model, for which dynamic analyses are carried out by both Time-History and CQC methods, where geometrically nonlinearity and simplified elastic foundation analogy are utilised. Besides anti-phase ground motion is considered. For the analyses, S16E component of 1971 San Fernando earthquake and East- West component of 1992 Erzincan earthquake are used as ground motion. With this aim, in the first chapter, the historical developments of suspension bridges in terms of construction and analysis are explained. Then, the formulation of general dynamic analysis, with in-phase and anti-phase ground motion, calculation of frequencies by a closed formed cable formulas, and formulation of elastic foundation analogy are presented. In the second chapter, the Bosporus Suspension Bridge as well as its mathematically model are introduced. The results obtained from the analyses are presented and discussed in the third chapter; conclusions drawn from these findings and suggestions are presented in the fourth chapter. Key Words : Suspension Bridge, Earthquake, Dynamic Analysis, Linear Analysis, Geometrically Nonlinear Analysis, Elastic Foundation Analogy, Anti-Phase Ground Motion, Time History Method, CQC Method VIII