Everything You Ve Wanted To Know About The Amazing Truss Arch Bridge

Different kinds of bridges ranging from arch bridges, metal truss bridges, to suspension bridges are constructed all over the world depending on the needs and the prevailing conditions at the construction site.The different kinds of bridges can be identified and differentiated by the construction materials and the bridge design. Bridges play an important role in our day-to-day lives, whether it is a toll bridge or a drawbridge over a section of a lake, river or even a footbridge, each one of them helps us to commute and reach our destinations.The sole purpose of a bridge is to make it possible or make it easier for people or goods to travel. At times, bridges are needed to establish commuting to far away remote areas. In some other cases, a bridge is required to significantly reduce transit time. As long as a bridge serves its purpose, it is good but often times it becomes difficult to finalize the overall design plan for a bridge. The surroundings of the bridge, the frequency of travel, and the distance between the bridge and nearby areas are some of the points considered before bridge plans are finalized. The difficulties which have arisen in the past during the construction of a bridge have led to new innovations and bridge designs such as cantilever bridges and modern arch bridges.Constructing a bridge means striking the perfect balance between the ideas and plans of an engineer and the construction process of the bridge. Bridges are balanced on a superstructure and a substructure. The function of the superstructure is to bear the load of the bridge deck. Different kinds of superstructures include truss, deck slab, and girder. The type of superstructure to choose depends on the design of the bridge and what the bridge is made up of, whether it is steel or concrete or composite. The superstructure is responsible for bearing the load of any vehicles passing over the bridge but ultimately the load is passed on into the earth using a substructure. Footings, abutments, piers, and pillars are different kinds of substructures responsible for transferring the load carried by the superstructure into the earth. Beam bridges and truss bridges are two of the most common types of bridges all over the world. The first-ever truss bridge was built in 1820 by Ithiel Town. Following this, truss bridges began to be built all over America due to their simplistic design and enormous load-bearing capacity. The design of interconnecting triangles was the main reason behind truss bridges being so strong.What are the different types of bridges?There are various kinds of bridges in the world when classified by the design and structure of these bridges. In general, the three main types of bridges in the world include arch bridges, suspension bridges, and beam and truss bridges. Other than these three main types of bridges, there are in total seven kinds of bridges that are commonly seen all over the world.These bridge types include cantilever bridges, suspension bridges, arch bridges, cable-stayed bridges, truss bridges, tied-arch bridges, and beam bridges. During the construction of a cantilever bridge, a vertical pillar is anchored into the ground to support the load of the horizontal deck which spans from one end of the bridge to the other. At times, a cantilever bridge is also supported with trusses. The cantilever truss mechanism takes some weight off the deck and it is transferred to the abutments and piers. Currently, Canada’s Quebec Bridge holds the record for the longest cantilever bridge in the world. even though it was constructed more than 100 years ago in 1919. It extends 1,800 ft (548.6 m), taking over Scotland’s Forth Bridge in terms of the maximum existing length of a cantilever bridge. Even in the United States, there are several cantilever bridges such as the San Francisco-Oakland Bay Bridge and Conde B. McCullough Memorial Bridge.Suspension bridges are pretty amazing to look at and they stand on vertical pillars which are connected by suspension cables leading to the name of the bridge, suspension bridge. The best example of a suspension bridge is the famous Golden Gate Bridge of California. In a suspension bridge, there are small vertical suspenders attached to the suspension cables, and these suspenders play a vital role. The major drawback of a suspension bridge is that it is vulnerable to sway or vibrate during a lot of traffic or in strong winds. Although, since technology has advanced, the chances of such instances taking place on a suspension bridge are very low.Arch bridges are also an integral part of world history. Historical surveys have proved that the Romans constructed over 1,000 arch bridges of stone during their time and surprisingly, some of them can be found even today. Although nowadays with heavy vehicle goods passing over arch bridges, an arch bridge is now made up of concrete rather than stones. Arch bridges use the principle of compression to use the load on the arch bridge and the gravity pulling it down to hold the bridge. Keystone, a central stone in an arch bridge, plays a key role in keeping an arch bridge straight. Interestingly, unlike many other bridges, fixed arch bridges can in fact be destabilized using temperature fluctuation as and when needed.A cable-stayed bridge is another engineering marvel and is a variant of the suspension bridge. Unlike a suspension bridge, a cable-stayed bridge connects the bridge directly to the towers which are the continuation of the base pillars. There are no suspension cables in a cable-stayed bridge, instead, the suspenders are the ones that keep the deck stable. Examples of cable-stayed bridges include the Russky Bridge in Russia and Stonecutters Bridge in Hong Kong. The longest cable-stayed bridge in the world is the Jiashao Bridge in China with a length of 8,792 ft (2,679.8 m).A truss bridge is a bridge is known to disperse its entire load into multiple small sections which are fitted together. Bridge trusses are usually bounded together by riveted, welded joints in triangles. These bridges were made of wood back in the 1800s but then there was a shift to steel and concrete, leading to the innovation of different kinds of truss design. Truss bridges are found in various arrangements and configurations. Some well-known truss designs include howe truss, warren truss, fink truss, parker truss, and whipple truss. Bowstring bridges or tied-arch bridges are other types of bridges and are a combination of the suspension bridge and the arch bridge. Contrary to the arch bridge where the arch lies below the road, in a tied arch bridge the arch lies above the road. Just like suspension bridges, there are vertical wires in a tied arch bridge that keep the bridge stable and support its load. A tied-arch bridge can be found in all parts of the world, especially in the United States. The Fort Pitt Bridge in Pittsburgh, US is an example of a tied arch bridge. Daniel W. Hoan Memorial Bridge and the Lowry Avenue Bridge are also examples of tied-arch bridges.Despite all the different kinds of bridges in the world, the simplicity of the beam bridge makes it the cheapest and was the first-ever bridge to be ever built. For constructing a beam bridge, there needs to be a crossbeam depending on the span of the bridge, the distance to be covered, and vertical columns. The number of vertical columns or piers required will depend upon the length of the bridge. Beam bridges are often built when a lot of distance has to be covered and there is constant traffic on the bridge. Some examples of beam bridges include Yolo Causeway in California and Lake Pontchartrain Causeway, Louisiana.Forces That Influence Different Bridge DesignsWith all these different kinds of bridge designs and further designs of a particular kind of bridge, the question often arises of which kind to build. Whether an arch bridge or a beam bridge should be built, or if engineers should take inspiration from different truss design bridges like the Howe truss and Warren truss bridge design are frequently asked questions when approaching the design of a bridge. The decision depends on a number of natural and man-made factors.Once the topographical conditions are settled about where the bridge is going to be built, a number of natural forces come into play which leads to the decision of which kind of bridge to build. The first factor is gravity as, unlike most other structures, a bridge has empty space under its surface. Gravity pulls it down and it is the task of engineers to pick the correct bridge design to counter the gravity, keeping in mind the load of the bridge. The load of the bridge is another factor. The total weight of the bridge is not only how much it weighs but also the weight of the vehicles and the load they carry. Depending on the potential load which the bridge will carry and its length, engineers need to decide on a design that will tick all the boxes and will successfully bear the load. Several natural forces especially wind movement can lead to potential disasters. Engineers have to keep in mind the shear, torsion, and resonance during designing the bridge. All modern bridges take into consideration all these natural forces to avoid any fatal disasters. Some other factors which are discussed before finalizing a design include the climatic conditions of the area, physical features of the area, economic costs of each design, and also the availability of labor forces.Common Types Of Bridges By FunctionBridges cannot only be differentiated on the basis of their design or the material they are made up of, there are several other criteria as well. One such criterion is function. Over the years, bridges have been distinguished based on the function they perform. There are different kinds of bridges based on the functions they perform.A double-decked bridge is built in densely populated areas for dealing with a great amount of traffic. A double-decker bridge in China, the Yangsigang Yangtze River Bridge, has six lanes on its upper deck in each direction and on the sides there is a pedestrian footpath along with sightseeing areas. Along with the upper deck, there also exists a lower deck which has four more lanes, two each for non-motor vehicles and pedestrian walkways. The division between motorized and non-motorized lanes helps keep the traffic moving at a steady pace. If the sole function of a bridge is to help pedestrians cross a stream or a canyon or even high-speed roadways, it is known as a footbridge or a pedestrian bridge. In marshy or sandy lands, there are swing bridges to help people to cross. When it is not possible to build pipelines underground, they are carried using bridges. These bridges are known as pipeline bridges. The sole purpose of this kind of bridge is to carry a liquid or gas-bearing pipeline across a river or a place that cannot be dug.Another popular kind of bridge is the train bridge. Truss bridges are usually used for this purpose. Researchers have concluded that a truss bridge is stronger than an arch bridge or even a beam bridge. The reason behind this is the interconnecting triangular structure of a truss bridge. Railroad bridges, military bridges as well as various covered bridges use the truss design. Trusses are used during construction. Additionally, most of these trusses are typically made of Aluminum Alloy FA6815 H14SR or ASTM A36 Grade Plate.Types Of Bridge MaterialsA bridge can be made up of almost anything. There are historic bridges made of stones and then there are bridges in jungles made of wooden logs or even vines. There are some materials that should be used in the construction of a bridge under ideal conditions as they help maintain the strength of the bridge. Iron rods and wire rope are perhaps the best options. However, there are many other common materials that are used all over the world for the construction of bridges.Wood is a material that was earlier used quite a lot for bridge construction especially during the 1800s when the concept of the iron bridge had not yet been established. With the advancement of technology, people began using more durable options such as reinforced concrete or iron in place of wood as the latter was vulnerable to termites, warping, and splintering as well. Using stones for constructing bridges was a part of Roman history where deck arch bridges were constructed using stones. Stones were a low maintenance option and fairly durable as well but with time, most of these bridges were demolished and were replaced with steel arch bridges or girder bridges. As human civilization advanced, it began using concrete and steel for building bridges, especially for long-distance bridges. They were stronger than the previously used ones. As people became more and more aware of the environmental harm which was being caused due to such heavy construction materials, there were some changes in the materials used. Nowadays a number of bridges are constructed using high-performance concrete, composite materials, and fiber-reinforced plastics.Metal Truss Bridge ConfigurationsA metal truss bridge can be constructed with various different configurations and arrangements. There are a lot of minute little details which lead to the differentiation of metal truss bridges. The majority of these designs were made in the early part of the 20th century but are relevant to date and are used by engineers as and when needed.Some metal truss bridge configurations include Pratt truss, Pratt Half-Hip, Double-Intersection Pratt, Howe truss, Parker truss, Baltimore, Camelback, Pennsylvania truss, and Warren truss bridges. There are several types of Warren truss bridges such as Polygonal Warren, Warren (with verticals), Quadruple-Intersection Warren and Double-Intersection Warren. Moreover, there are some other types of metal truss bridges too like Stearns, Thacher, Pegram, Kellogg, Lenticular, Post, Queenpost, Kingpost, Bollman, Bowstring, and K-Truss. The K truss bridge has a unique design and its idea is to break the vertical members of the bridge into smaller sections to ensure better weight distribution.Metal Truss ConnectionsMetal truss bridges have been in use for years and with progress in time, there have been several changes regarding the manner in which truss members are joined. As of today, there are a total of three metal truss connection methods known and metal truss bridges are even classified based on the kind of connection they have.The three different types of connections are pinned, riveted, and bolted. Pinned connections were the first ones to be used, it was quite easy to assemble them but around 1910 they were replaced with riveted connections as the latter was more rigid. Eventually riveted connections were also replaced with welded or bolted connections instead of rivets. Bolts are now used to fasten members onto the gusset plates.