Bridges, structures engineered for crossing mountain ranges, freeways, ocean bays, and rivers are much more complex than one might think. Did you know that there are four main types of bridges, and each one serves a completely different purpose?
{Pont de Gard, an arch bridge}
Let’s start with the arch bridge. This bridge goes far back into history, to the time of the Roman Empire, where they were built using only stone. Perhaps the most famous is the Pont du Gard, which is as old as the entire Christian religion. Because of this 2,000 year old history, we might guess that it is still around today for a reason. Its natural strength is amazing. Designed to span across canyon gorges or valleys, it can typically only span from 200 to 800 feet. This would be classified as a short-spanning bridge. The weight from the travelers on the bridge carries all along the arch to the ends, where the weight is split between two abutments, which are the end points of the arch.
There can be some weaknesses to this bridge. The arch design can be time consuming to build. The basic structure of the arch bridge hasn’t changed dramatically over time, only the outside design and materials, which proves how successful it is.
{Train traveling on a beam bridge}
The beam bridge, the most practical, dependable, and popular of the bridges, is considered a small bridge, spanning usually around 120 feet and is only good for a limited amount of distance. This fairly inexpensive bridge, in comparison to others, serves mainly as a highway overpass for trains and cars. If thought out perfectly, the beam bridge can span miles long, but only if there are enough beams to support it. The Lake Pontchartrain Causeway in Louisiana is almost 24 miles l...
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... cable-stayed bridges, the cables come up to support the towers, which then carry the load.
There are two main different ways of arranging the cables for the cable-stayed bridges: the radial pattern and the parallel pattern. For the radial pattern, all the cables meet up on the same place on the tower and at different positions on the road. For the parallel pattern, the cables are parallel to each other and all meet up at different heights and lengths.
{Parallel and Radial Cable Patterns}
The cable-stayed bridge is a medium-span bridge, running anywhere from 500 to 2,800 feet. They are quickly becoming the most popular modern bridge. There is only one main complaint for this bridge, and it is that they don’t run as far in length as the suspension. If they are as popular as the articles say they are, I am sure they will surpass the suspension length soon.
Truss bridges can be built three different ways—as a pony bridge, through bridge, or deck bridge. A pony bridge, or a bridge in which the bracing is only on the sides and on top of the deck, are most often used when having a lighter load as there
The 1.78 mile western span of the bridge between San Francisco and Yerba Buena Island presented the first obstacle. The bay was up to 100 feet deep in some places and required a new foundation-laying technique. Engineers developed a type of foundation called a pneumatic caisson to support the western section. A series of concrete cylinders were grouped together and then capped-off, having the air pressure of each cylinder identical to balance the beginning of the structure. From there, the workers added sets of new cylinders until the caisson reached the bottom of the bay. Then, in order to reach the bedrock, they inserted long drills down the cylinders, digging until they reached bedrock. After the caisson was balanced at the bottom of the bay, workers filled it with 1 million cubic yards of concrete, more concrete than was used for the construction of the Empire State Building! This caisson connected the two suspension bridges that make up the western part of the bridge.
At the time of its construction in 1929, the Ambassador Bridge was the largest spanned suspension bridge at 564 meters until the George Washington Bridge was built. It was an engineering masterpiece at the time. The total bridge length is 2,286 meters and rises to 118 meters above the river. Suspension cables support the main span of the Ambassador Bridge and the main pillars under the bridge are supported by steel in a cantilever truss structure. In total, the McClintic-Marshall masterpiece is comprised of 21,000 tons of steel. The immense socio-economical impact that the Ambassador Bridge has on transportation and trade is imperative for daily interaction between the Un...
The area of where the bridge was to cross the Ohio River was said to be one of the hardest places to build but came with some advantages. The section of the river had a solid rock base for the supporting pier to be built on. Since the engineers knew they could build a pier that would not settle they decided on a continuous bridge design. This design type distributes the weight so the steel trusses could be smaller and riveted together. This alone saved an estimates twenty percent of steel that was originally thought to be need to make the bridge cutting down the cost. The two continuous trusses span a collective 1,550 feet across the water. With addition of the north and south approach viaducts, for trains to go under the bridge, the superstructure’s total length is 3,463 feet. The bridge was made to hold two sets of tracks making the width 38 feet and 9 inches. The design called for 27,000 cubic yards of concrete and 13,200 tons of steel with some members being four foot square beams that span a distance of seventy feet. The design was the first step in a long process that would take several years to
According to Suspension bridges: Concepts and various innovative techniques of structural evaluation, “During the past 200 years, suspension bridges have been at the forefront in all aspects of structural engineering” (“Suspension”). This statement shows that suspension bridges have been used for over 200 years, and that people are still using them today because they are structurally better bridges. This paper shows four arguments on the advantages of suspension bridges, and why you should use one when building a bridge. When deciding on building a suspension bridge, it has many advantages such as; its lightness, ability to span over a long distance, easy construction, cost effective, easy to maintain, less risk
The Tacoma Narrows Bridge was possibly the luckiest engineering catastrophe if there ever was one. Despite the very real danger, no human life was lost and engineers and the human race alike are better off for it.
The bridge was designed at a time when America was moving toward streamline products, this included the design of bridges. The Tacoma Narrows Bridge was a sleek, graceful looking suspension bridge. Suspension bridges consist of many cables anchored...
First and foremost, when you decide to build something this size, in the most extreme environment possible, you must select your primary construction materials very carefully. In the case of the space elevator it’s not just wear and tear but the immense pull of earth’s gravity vs. the centrifugal force of the spin of the earth. These forces both work against the construction and maintenance of the elevator. The only material every dreamed up to survive this intense game of tuga-war is a carbon nanotube cable. These nanotubes were chosen to support the cable structure because they can withstand unearthly amounts of tension and stress. In concept, the massive cable will be stretched from an orbital platform down to an offshore sea platform thus creating the all important track that would guide the “elevator cars” up and down
"The arch enables wide spaces to be crossed by the use of the minimum of materials, thus relieving weight which would otherwise put an intolerable burden on the structure" (Kamm, n.d., para 6).
The preferred alternative of ODOT is to widen and improve the structural integrity of the Yaquina Bay Bridge. The widening of the bridge shall follow the AASHTO LRFD Bridge Design Specification (Baker, 2008, p.3) using steel pier cap extensions (Quesnell Bridge Widening). The structural integrity of the bridge is to be enhance by improving the fatigue life of welds (Bennett, Matamoros, Barett-Gonzalez, & Rolfe, 2014, p.8)
The cables are supported by four steel towers, one at each corner of the grid.
A total of nine spans will used with three being 450 feet in length and six being 150 feet in length. 70 kips per square inch steel will be used for all structural members. Seven girders will be used for each span, all with slender webs, compact flanges and transverse stiffeners for buckling support. The dimensions for the 450-foot
The Bunker Hill Bridge in Catawba County in North Carolina was built in 1895 and reconstructed in 1994. The bridge is significant because it is the only remaining historic type of "Improved Lattice Truss" bridge. This historic construction was patented in 1839 by Herman Haupt and in 1894, commissioners of Catawba County asked the residents to construct a bridge over Lyles creek. The Haupt truss design is of civil engineering interest because it is an example of innovation in mid 19th century bridge engineering and a construction associated with Herman Haupt, who was a prominent civil engineer in the 19 century and well known for his pioneering projects in the analysis of bridges (Bennet, 4). This paper will summarize the event by reporting
The current westbound bridge was designed and rebuilt with open trusses, stiffening struts and openings in the roadway to let wind through. Like other modern suspension bridges, the westbound bridge was built with steel plates that feature sharp entry edges rather than the flat plate sides used in the original Tacoma Narrows Bridge
The bridge would be made out of a series of layers of arches, rather than being a solid wall, so as to lessen the amount of materials used while still maintaining an equal strength. The conduit bridge would be constructed using wooden scaffolding, out of the same materials as the submerged conduit. The arches of the Aqueduct would be constructed by using a wooden “centering” device, which would be placed where one wanted the arch to go, and the stones of the arch would be placed around the device, and once the keystone was added, the device could be removed and another arch could be