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Wind Effects on Long-Span Bridges

Wind Effects on Long-Span Bridges 57.1 57.2 Introduction Winds and Long-Span Bridges Description of Wind at Bridge Site • Long-Span Bridge Responses to Wsection modelind 57 57.3 Experimental Investigation Scaling Principle • Section model • Full Bridge Model • Taut Strip Model 57.4 Chun S. Cai Florida Department of Transportation Analytical Solutions Vortex Shedding • Galloping • Flutter • Buffeting • Quasi-Static Divergence 57.5 Practical Applications Wind Climate at Bridge Site • Design Consideration • Construction Safety • Rehabilitation • Cable Vibration • Structural Control Serge Montens Jean Muller International, France 57.1 Introduction The development of modern materials and construction techniques has resulted in a new generation of lightweight flexible structures | Cai C. Montens S. Wind Effects on Long-Span Bridges. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 57 Wind Effects on Long-Span Bridges 57.1 Introduction 57.2 Winds and Long-Span Bridges Description of Wind at Bridge Site Long-Span Bridge Responses to Wsection modelind 57.3 Experimental Investigation Scaling Principle Section model Full Bridge Model Taut Strip Model 57.4 Analytical Solutions Vortex Shedding Galloping Flutter Chun S. Cai Buffeting Quasi-Static Divergence Florida Department 57 5 Practical Applications of Transportation Wind Climate at Bridge Site Design Consideration Serge Montens Construction Safety Rehabilitation Cable Jean Muller International France Vibration Structural Control 57.1 Introduction The development of modern materials and construction techniques has resulted in a new generation of lightweight flexible structures. Such structures are susceptible to the action of winds. Suspension bridges and cable-stayed bridges shown in Figure 57.1 are typical structures susceptible to wind-induced problems. The most renowned bridge collapse due to winds is the Tacoma Narrows suspension bridge linking the Olympic Peninsula with the rest of the state of Washington. It was completed and opened to traffic on July 1 1940. Its 853-m main suspension span was the third longest in the world. This bridge became famous for its serious wind-induced problems that began to occur soon after it opened. Even in winds of only 3 to 4 miles per hour the center span would rise and fall as much as four feet. and drivers would go out of their way either to avoid it or cross it for the roller coaster thrill of the trip. People said you saw the lights of cars ahead disappearing and reappearing as they bounced up and down. Engineers monitored the bridge closely but concluded that the motions were predictable and tolerable 1 . On November 7 1940 4 months and 6 days after the bridge was opened the deck oscillated through large .