tailieunhanh - Towers

Towers Introduction Functions Aesthetics Concept Design Materials • Forms and Shapes • Erection Final Design Design Loads • Design Considerations Construction Summary Introduction Towers are the most visible structural elements of long-span bridges. They project above the superstructure and are seen from all directions by viewers and by users. Towers give bridges their character and a unifying theme. They project a mnemonic image that people remember as a lasting impression of the bridge itself. As examples of the powerful imagery of towers, contrast the elegant art deco towers of the Golden Gate Bridge (Figure ) with the utilitarian but timeless architecture of the towers of. | Seim C. Towers. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 28 Towers Charles Seim T Y. Lin International Introduction Functions Aesthetics Concept Design Materials Forms and Shapes Erection Final Design Design Loads Design Considerations Construction Summary Introduction Towers are the most visible structural elements of long-span bridges. They project above the superstructure and are seen from all directions by viewers and by users. Towers give bridges their character and a unifying theme. They project a mnemonic image that people remember as a lasting impression of the bridge itself. As examples of the powerful imagery of towers contrast the elegant art deco towers of the Golden Gate Bridge Figure with the utilitarian but timeless architecture of the towers of the San Francisco-Oakland Bay Bridge Figure . Or contrast the massive rugged stone towers of the Brooklyn Bridge Figure with the awkward confusing steel towers of the Williamsburg Bridge in New York City Figure . Towers can be defined as vertical steel or concrete structures projecting above the deck supporting cables and carrying the forces to which the bridge is subjected to the ground. By this definition towers are used only for suspension bridges or for cable-stayed bridges or hybrid suspension-cable-stayed structures. The word pylon is sometimes used for the towers of cable-stayed bridges. Both pylon and tower have about the same meaning a tall and narrow structure supporting itself and the roadway. In this chapter the word tower will be used for both suspension and for cabled-stayed bridges to avoid any confusion in terms. Both suspension and cable-stayed bridges are supported by abutments or piers at the point where these structures transition to the approach roadway or the approach structure. Abutments are discussed in Chapter 30. Piers and columns that support the superstructure for other forms of