Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Civil Engineering

Suspension bridge can withstand earthquake movements better than other types. The history of bridges failure shows that aerodynamic instabilities are the main reason of such bridges failure. All this make a great realization of the aeroelastic nature of the wind phenomena, Wind action is one of the most important phenomenon in the design that control long span suspension bridges. To increasing the stiffness of suspension bridges against aeroelastic instability we should make various trials and arrangements of cables and hangers which make the torsional stiffness increases with respect to the flexural stiffness taking into consideration the symmetrical and anti-symmetrical modes. If that occurs stiff structure can achieved with strong stiffness against lateral loads especially under extreme wind velocities. In this research it's required to explore the effect of changing the angle of cable plane including the main cables and suspenders on the improvement of critical wind velocity. The differences in the behavior of the structure with respect to mode shapes and straining actions of girder and main cables is studied with respect to the change in suspenders angle (zero, 10, 20, 30 degree)

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