Tham khảo tài liệu 'structure steel design's handbook 2009 part 17', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | SECTION 15 CABLE-SUSPENDED BRIDGES Walter Podolny Jr. . Senior Structural Engineer Office of Bridge Technology Federal Highway Administration . Department of Transportation Washington . Few structures are as universally appealing as cable-supported bridges. The origin of the concept of bridging large spans with cables exerting their strength in tension is lost in antiquity and undoubtedly dates back to a time before recorded history. Perhaps primitive humans wanting to cross natural obstructions such as deep gorges and large streams observed a spider spinning a web or monkeys traveling along hanging vines. EVOLUTION OF CABLE-SUSPENDED BRIDGES Early cable-suspended bridges were footbridges consisting of cables formed from twisted vines or hide drawn tightly to reduce sag. The cable ends were attached to trees or other permanent objects located on the banks of rivers or at the edges of gorges or other natural obstructions to travel. The deck probably of rough-hewn plank was laid directly on the cable. This type of construction was used in remote ages in China Japan India and Tibet. It was used by the Aztecs of Mexico the Incas of Peru and by natives in other parts of South America. It can still be found in remote areas of the world. From the sixteenth to nineteenth centuries military engineers made effective use of rope suspension bridges. In 1734 the Saxon army built an iron-chain bridge over the Oder River at Glorywitz reportedly the first use in Europe of a bridge with a metal suspension system. However iron chains were used much earlier in China. The first metal suspension bridge in North America was the Jacob s Creek Bridge in Pennsylvania designed and erected by James Finley in 1801. Supported by two suspended chains of wrought-iron links its 70-ft span was stiffened by substantial trussed railing and timber planks. Chains and flat wrought-iron bars dominated suspension-bridge construction for some time after that. Construction .
