Bridges designed for modern infrastructure will usually be constructed of steel or reinforced concrete, or a combination of both.
They are often made of metal, specifically steel or iron, but can also be made of wood. Insert picture example. All About that Bridge.
Search this site. Navigation All About Our Website. Comparing and Contrasting Bridges. Golden Gate Bridge. Our Task. Engineering process. This chart helps you to define and identify different types of bridges. By exploring this chart you can learn about the differences and similarities of Arch, Suspension, Beam, and Truss bridges. The light-weight, yet stiff, nature of truss bridges also makes them ideal for demountable bridges. Most modern arch bridges are made from reinforced concrete In all modern suspension bridges, the roadway hangs from massive steel cables, which are draped over two towers and secured into solid concrete blocks, called 'anchorages', at both ends of the bridge.
Suspension bridges require anchorages strong enough for the tension, or angular pulling, on the suspension cables. Solid rock or a large mass of stable concrete is the preferred geological base for an anchorage. These massive anchorages carry the entire weight of the bridge, and their weight must exceed the combined weight of the bridge and the vehicular load. One of the newest large suspension bridges in the U. The new bridge is the fifth-longest suspension bridge in the U. Cable-stayed designs dominate most other large bridge projects.
A newly proposed cable-stayed bridge called the John James Audubon Bridge would include a 2. If completed, it will be the longest of its kind in North America. Table of Contents. There are also designs that transmit tension through bridge cables which allow a degree of flexibility for different terrains.
One interesting factor when looking at different bridge designs is their longevity and the fact they have been around for centuries. We will now take a look at the different types of bridges and how they work. A beam bridge is one of the simplest types of bridge. A perfect example being a basic log bridge — something you may see while out on a country walk.
The deck area traditionally consists of wood plank or stone slabs often referred to as a clapper bridge. Very often you will find other beams, positioned in between the main beams, offering additional support and stability. The area over which people or vehicles travel will be a simple decking positioned vertically across the underlying beams. There is no transfer of stress which you see in arch structures and other types of bridges. The truss bridge has been around for literally centuries and is a load-bearing structure which incorporates a truss in a highly efficient yet very simple design.
You will notice an array of different variations of the simple truss bridge but they all incorporate triangular sections. The role of these triangular elements is important because they effectively absorb tension and compression to create a stressed structure able to accommodate dynamic loads.
This mixture of tension and compression ensures the structure of the bridge is maintained and the decking area remains uncompromised even in relatively strong winds.
When the first cantilever bridge was designed it was seen as a major engineering breakthrough. The bridge works by using cantilevers which may be simple beams or trusses. They are made from pre-stressed concrete or structural steel when used to accommodate traffic. When you consider that the horizontal beams making up the cantilever arm are only supported from one side it does begin to sound a little dangerous.
The bridge load is supported through diagonal bracing with horizontal beams as opposed to typical vertical bracing. Extremely safe and very secure, the design of cantilever bridges is one which still lives on today. There are many different types of arch bridge but they all have central elements in common. Each bridge has abutments, which are used to support the curved arch structure under the bridge. The most common type of arch bridge is a viaduct, a long bridge made up of many arches.
The lateral pressure created by the arch span is transferred into the supporting abutments. It is therefore essential that these parts of the bridge remain solid, intact and well founded. You will see many arch bridges with decorative brickwork which is an integral part of the design. Simple yet so very effective an arch bridge can carry everything from pedestrians to heavy rail.
The tied arch bridge is a fascinating design which incorporates an arch structure usually metal supported by vertical ties between the arch and the deck.
The tips of the arch structure are connected by a bottom chord. This acts in a similar fashion to the string of a bow. The downward pressure from the arch structure to the deck of the bridge is translated into tension by the vertical ties. Many people assume that the abutments ensure that the tied arch bridge and arch structure stay in place.
The best example of this is a bowstring which absorbs pressure, keeping both sides of the bow in contact, until it eventually flattens out. The structure of a stereotypical suspension bridge looks very simple but the design is extremely effective. The deck of the suspension bridge is the load-bearing element of the structure.
This is held in place by vertical suspenders which support the cables. The suspension cables extend out beyond each side of the bridge and are anchored firmly into the ground.
It will depend upon the size of the bridge but a number of towers will be installed to hold up the suspension cables. Any load applied to the bridge is transformed into tension across the suspension cables which are the integral part of the structure. Cables are connected from the pylons to the deck below.
Either directly from the top of the tower or at different points of the column.
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