Kaedah Unsur Terhingga (Perbincangan Ringkas) (Mungkin 2024)
Jambatan gantung, jambatan dengan kabel overhead yang menyokong jalannya. Salah satu bentuk kejuruteraan yang paling tua, jambatan gantung dibina oleh masyarakat primitif menggunakan tanaman merambat untuk kabel dan memasang jalan raya langsung di atas kabel. Jenis yang lebih kuat diperkenalkan di India mengenai iklan abad ke-4 yang menggunakan kabel dari buluh anyaman dan kemudian dari rantai besi, dengan jalan raya digantung.
jambatan: Penggantungan
Jambatan gantung membawa beban menegak melalui kabel melengkung dalam keadaan tegang. Beban ini dipindahkan ke menara, yang membawa
Pada zaman moden ini, jambatan gantung memberikan jalan penyelesaian yang ekonomik untuk masalah jangka panjang di sepanjang sungai yang boleh dilayari atau di laman web lain di mana sukar dijumpai di dermaga. Jurutera Inggeris, Perancis, Amerika, dan lain-lain pada akhir abad ke-18 dan awal abad ke-19 menghadapi masalah kestabilan dan kekuatan yang serius terhadap kekuatan angin dan beban berat; kegagalan disebabkan oleh ribut, salji lebat, dan lembu ternakan. Kredit untuk menyelesaikan masalah ini adalah milik John Augustus Roebling, seorang jurutera Amerika kelahiran Jerman yang menambahkan kekuda web di kedua-dua sisi jalannya dan menghasilkan struktur yang begitu kaku sehingga berjaya menjembatani Niagara Gorge di Air Terjun Niagara, New York, Sungai Ohio di Cincinnati, dan, akhirnya, dalam karya agungnya, Sungai Timur antara Brooklyn dan Manhattan di New York City.
The technique of cable spinning for suspension bridges was invented by the French engineer Louis Vicat, a contemporary of Roebling. Vicat’s method employed a traveling wheel to carry the continuous cable strand from the anchorage on one side up over the tower, down on a predetermined sag (catenary) to the midpoint of the bridge, up and over the tower on the farther side to the farther anchorage, where a crew received the wheel, anchored the strand, and returned the wheel, laying a fresh strand. From these successive parallel strands a cable was built up.
Another major development in the modern suspension bridge was the pneumatic caisson, which permitted pier foundation at great depths. It was used initially by French, British, and American engineers, including Washington Roebling, who completed his father’s Brooklyn Bridge.
For a time in the 1930s, American engineers experimented with a narrow solid girder in place of the web truss to stiffen the roadway, but the failure of the Tacoma Narrows Bridge in 1940 under aerodynamic forces instigated a return to the web truss. Later, aerodynamically stable box girders replaced the web truss.
By the late 1980s, three suspension bridges (the Golden Gate, in San Francisco, the Verrazano-Narrows, in New York City, and the Humber Bridge, near Hull, England) had main-span lengths of more than 4,000 feet (1,200 metres). Modern steel alloys are considered capable of much greater spans. Though suspension bridges can be made strong enough to support freight trains, they have nearly all been designed for automobile traffic.
A cable-braced bridge was developed by German engineers at Cologne, Düsseldorf, and elsewhere in the 1950s and’60s; in this form a single tower at the midpoint supports the roadway by means of a number of cables. Another development of the 1960s, aimed at reducing time of construction, was cable fabricated in the shop.
