However, the expansion of the iron and steel industry in the 1800s resulted in a substantial shift in bridge technology. While wood and concrete bridges were still popular at the time, many manufacturers and designers chose metal parts because of their great tensile strength and longevity. The typical Victorian-era bridge was made of steel girders with wood decking or trusses. However, some engineers experimented with different materials such as cast iron, wrought iron, and even bamboo.
In the United States, the first bridge over the Ohio River was built in 1811 by John Cunningham. This bridge was a wooden covered wagon bridge that used pegs to connect the two ends of the span. In 1824, Daniel Turner constructed the first iron bridge over the Ohio River; this bridge used 100 tons of iron beams with timber pilings as support. In 1831, Joseph Daniels built the second iron bridge over the Ohio River; this bridge had a central section of iron rails with wooden flanges on either side. By 1840, there were more than 150 iron bridges in Ohio alone!
In Europe, major advances in bridge design came from George Stephenson's work in Scotland and England. In 1767, he developed a method for making wrought-iron plates that could be joined together without any welding process; this invention contributed to the development of mass-manufactured goods.
Wood, stone, iron, and concrete have been the four basic materials utilized building bridges. Iron has had the largest impact on contemporary bridges. Steel is created from iron, and steel is used to make reinforced and prestressed concrete. Concrete is by far the most common bridge material, with more than 90% of all bridges in the United States being made of this material.
Wood was the original bridge material for many cultures around the world. It is easy to work with and relatively inexpensive. Bridges made of wood are still in use today in some countries such as India and Indonesia. However, due to its low weight-to-strength ratio, it has been largely replaced by other materials for new structures.
Stone has been used for thousands of years and remains one of the most popular bridge materials today. Its durable nature makes it useful for structures that will be exposed to the weather or environmental hazards such as water, heat, and wind. One disadvantage of stone bridges is their high cost; large projects can become financially untenable without government assistance.
Iron has a long history as a bridge material; the first metal bridge over an ocean was built in France in 1663. Since then, iron has been used for many different types of bridges including cable-stayed, floating, truss, and suspension bridges.
With the Industrial Revolution in the nineteenth century, wrought iron truss designs were created for greater bridges, but iron lacks the tensile strength to carry high weights. With the invention of steel, which has a high tensile strength, increasingly greater bridges were created, many of which were inspired by Gustave Eiffel's designs.
Iron and steel have differences when it comes to bridge construction. While iron is heavy and hard to work with, it is strong enough to support large structures. Steel is lighter and easier to work with, but it must be carefully designed so that it does not fail under its own weight. Bridges made from these materials are described as "iron" or "steel" bridges.
The first true suspension bridge was built in 1867 by Alexander Hamilton Leary. He called this design "the world's first practical continuous truss." It crossed the Niagara River between Canada and America. Another major breakthrough in bridge technology came in 1889 with the completion of the Golden Gate Bridge in San Francisco. This bridge uses wire cables instead of iron or steel girders as its main support. It is one of the earliest examples of a self-anchored suspension bridge system today used on many modern bridges.
Other important advances in bridge technology has led up to today. In 1937, Howard Pyle Boyd invented the ballistite bridge. This type of bridge uses gas explosions to create an instantaneous beam section of some sort.
The introduction of the steam locomotive in the mid-18th century signaled the beginning of a new era in bridge design. Bridges were required to handle higher weights across longer spans, necessitating the use of a stronger material. In 1741, iron was used for the first time to bridge the "Tees" river in England. Steel had become the material of choice by the 1880s.
The first true steel bridge was built in 1867 by Andrew Carnegie. It spanned the Humber River in Yorkshire, England and is considered the birthplace of modern bridge construction. Since then, steel has remained the primary material used for bridges because of its strength-to-weight ratio. Modern bridges are usually constructed with multiple layers of steel girders that support roadways and rail lines.
The Brooklyn Bridge in New York City was the first major suspension bridge built with steel girders. The structure opened in 1883 and was designed by John A. Roebling's son, Washington J. Roebling. It was also one of the first bridges to be lit at night. The Golden Gate Bridge in San Francisco was the next major suspension bridge built with steel girders and it too was designed by a son of John A. Roebling (this time of Louis II). It opened in 1937 and remains one of the most popular tourist attractions in California. The world's longest cable-stayed bridge, the Dali Zhangjiang Bridge in China, was completed in 2008.
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