1. Cantilever Bridge (1882)
Baker and Fowler accomplish a daring feat of structural engineering.
Between 1882 and 1890, construction of the one of the most ambitious engineering projects of the time took place near Edinburgh, Scotland. The project was to create a railway bridge that would span the Firth of Forth, one of Scotland's major tributaies, and connect the northeast and southeast of the country. The men who step forward to take up this challenge were Benjamin Baker (1840-1907) and John Fowler (1817-1898). Artist William Morris described it as "the supremest specimen of all ugliness," but their design became an national icon and set a new standard in engineering.
Baker and Fowler were chosen in 1882 to replace the previous designer of the Forth Rail Bridge, Sir Thomas Bouch, when one of his projects, the Tay Bridge, collapsed in 1879 killing seventy-five people. Baker and Fowler has an estabilished pedigree of engineering in Victorian Britain, their achivements including the construction of the Metropolitan Line, the first underground line in Landon, as well as many other railway bridges. They opted to design a cantilever bridge to span the Firth of Forth, using 64,000 tons of steel as their building material. This was the first bridge to be built from this material.
The principle behind a cantilever bridge is one of balance. The bridge is projected out over the gap that needs to be spanned and counterbalanced at the shore end.Often two bridges are used, one from each side, and where the ends meet there is a third section, a simple beam bridge, to cover the gap. The idea of using cantilever in bridge was not an entirely new one. But what made Baker and Flower's construction unique was the sheer scope of the project.
At most than 3,280 feet(1,000 m), the Forth Rail Bridge is the second longest cantilever bridge in the world.
2. Steel-girder Skyscraper (1884)
Jenney devises a way of building in the sky.
Before the advent of the skyscraper, tall buildings were built to showcase great wealth, power, or religious beliefs. For the architect and civil engineer William Le Baron Jenney (1832-1907), the urge to build great edifices was born from a necessity to solve commercial (and later residential) needs in his native Chicago, where ground space was at a premium.
Two obstacles to the construction of highrise buildings were overcome in the mid-nineteenth century, paving the way for the skyscraper. In 1853 Elisha Graves Otis devised a mechanism to prevent elevators from falling if their cable broke, enabling passengers to be transported upward safely. The second breakthrough came with a steel-framed structure that could support the entire weight of its walls, instead of the traditionalload-bearing walls that carry the building's weight.
Jenney's ten-story Home Insurance Campany Building, built in Chicago in 1884 and 1885, was the first to use an internal framework, or skeleton, made from steel columns and girders as well a curtain wall that was fix to the steel structure. Architects were soon racing to design bigger skyscrapers, especially in New York where there were no laws restricting height.
Since Jenney's design, skyscrapers built with glass have been able to withstand severe weather, including earthquakes. Building have incorporated plazas and parks alongside numerous entertainment and consumer venues at street level. Energy conservation is paramount to all future design in the twenty-first century. Today the skyscraper is and increasingly familiar sight, springing forth in growing numbers in cities all across the world-especially Hong Kong, Shanghai, and Dubai, as well as Chicago once again- shaping the way we live within urban centers.
"The skyscraper establishes the block, the block creates the street, the street offers itself to man."
-Roland Barthes, literary and social theorist.
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