How are suspension bridges made?

How are suspension bridges made?

Towers are erected atop caissons in the case of suspension bridges. Originally made of stone, suspension bridge towers are now made of steel or concrete. The anchorages are then constructed on both ends, typically of reinforced concrete with embedded steel eyebars to which the cables will be anchored. The central part of the bridge is then built up out of many long trusses or girders that cross between the anchors and join together at their other ends. The distance between the centers of the two towers determines the width of the bridge.

Suspension bridges can be divided into three general types: single-span, multiple-span, and self-anchored. A single-span suspension bridge has a single main cable supporting the weight of the deck. Multiple-span bridges have several independent suspension cables running from each side tower to the center pier or girder. Self-anchored bridges lack any kind of support beneath the decking material. Instead, these bridges rely on the tension in their suspension cables for their stability.

Bridge construction is a very labor-intensive process. Even today, after all modern tools have been invented to save time, it still takes about as much time to build a bridge as it did when builders had only their hands and hammers available to them. A suspension bridge needs more work than a flat-deck bridge because its center section must be able to hold up under its own weight as well as the weight of vehicles crossing it.

How does a bridge get built?

When a bridge over a body of water requires piers, foundations are formed by lowering caissons into the riverbed and filling them with concrete. The central part of the bridge is then built up out of decking materials like wood or metal, which are attached to the anchorages, forming a level road surface across the river or lake.

For bridges without piers, such as many wooden bridges, load-bearing elements called "stringers" are used instead. These are long, thin pieces of lumber that are placed side by side under the roadway, with one end resting on the ground and the other hanging in the air. The middle part of the stringer is left open, so it can support traffic loads. The ends of the stringers are chamfered (rounded) so they won't touch the ground or the sky. Instead, they contact short posts set into the ground at each end, which provide extra strength and stability. The space between each stringer and its post is called a "nogging" and helps distribute traffic loads more evenly across the bridge.

Once the stringers have been laid out, the next step is to build up the rest of the bridge.

How is the suspension bridge over the Severn built?

The foundations and towers of a suspension bridge are built first. The primary suspension cables are securely fastened to abutments at both ends of the bridge and are supported by the towers, which give the bridge its unique design. Hangers hung from these wires support the bridge deck. On larger structures, there may be several secondary suspensions that connect the towers to the middle pier or bents. These provide more stability for the bridge and help prevent it from being swayed by wind gusts.

When building a new bridge, first the location of the towers and piers must be determined. For example, if the goal is to have two equal-sized bridges off to each side of the river, then the location of the towers will determine how far apart they are on the riverbank. Next, the foundation materials should be selected and then poured as soon as possible after determining the size and shape of the tower sites. Once the foundations are complete, the cable-supporting structure can be erected above them.

On existing bridges, maintenance or repair work may require changes to the layout or suspension system of the bridge. For example, if one section of cable needs replacing, then it can be done without removing the entire bridge deck. The replacement cable would then be attached to new hangers mounted on the remaining structure.

Even with many years of use, a suspension bridge remains one of the most efficient ways to cross a large body of water.

How does a suspension bridge support a tower?

Suspension bridges are one of the most common types of bridges. It has a cable support system that distributes the bridge deck's weight between the two towers. The tension pressures in the cables are transferred to compression forces in the piers, which subsequently extend to the earth. The distance between the two towers determines how much load the bridge can carry.

The first suspension bridges were wooden and used girders as their main supporting structure. As technology improved, metal girders became popular. Today, most suspension bridges are made from steel wire cables supported by multiple vertical posts anchored into the ground at each end of the bridge.

Cables suspended within tubes provide lateral support for the bridge while the vertical posts connected to their ends carry the weight of the deck. The spacing of these posts depends on the load the bridge will bear. If the load is heavy, then more posts are needed. If the load is light, then fewer posts are enough. The number of cables required also depends on the load they will have to carry. If the load is heavy, then more cables are needed. If the load is light, then fewer cables are enough.

The bridge towers must be strong enough to support their own weight as well as the weight of any vehicles crossing it. They usually consist of large hollow cylinders with horizontal openings at the base to allow water to flow off the bridge when it is raining or when there is a flood warning.

About Article Author

Christopher Mcmullen

Christopher Mcmullen is a building contractor and home improvement specialist. Christopher loves working with his crews to help people achieve their goals of having a beautiful home.

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