Building a Waddell A-Truss Bridge
Introduction:
Bridges have been used for thousands of years, beginning with natural formations, such as huge rock arches (Appendix A). The first bridges made by humans were most likely simple spans of wooden tree trunks laid across streams, or planks, such as rafts tied together (Gascoigne, 2001). These simple designs evolved over time, as new materials became available, to form the hundreds of bridges we use today. Some basic bridge designs include truss, arch, beam and suspension bridges. The most basic of these is the beam bridge (Appendix B1), which consists of a deck, spanning a relatively short distance, that is held up by a pair of abutments (vertical supports at either end). When weight is placed on
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This means that it excessively designed, and can create excessive burdens on the cost, size and complexity (Sade, 2014). When designing large bridges, these three factors (excessive cost, size and complexity) regulate if a bridge is built, or if a different design is chosen. The Waddell A-truss bridge (Appendix C) is a truss bridge designed by engineer John Alexander Low Waddell. It was built in 1898, as a short span railway bridge, and is one of only two bridges remaining which had the A-truss design. Due to its high trusses, it is quite rigid in all directions, and it is easily erected as it has a simple design (Syazwi, 2013). These are some of the reasons why the Waddell a-truss design was chosen. It is simple to create out of the materials which can be used (Manila folders) as it consists of beams and bars, as well as some gusset plates (Appendix C). Not only this, but the design allows it to hold quite a large amount of weight, in spite of the fact that a folder is not necessarily strong. However when folded, it may be surprising how much a small piece of card can actually hold. Manila folders were used to create this bridge because they are inexpensive, easy to cut bend and glue, have surprisingly predictable structural behaviour and can be used to build tubes, bars and strong
The purpose of the Boomilever Project is to build a cantilevered truss that is light-weight while still able to support 15 kilograms. With this project it serves to reinforce the cumulative concepts that have been taught throughout this semester of Engineering Statics. It has been necessary to research designs, types of wood, and types of adhesive that will create a final result that is consistent with the
A simple beam bridge that is flat across and supported at the two ends. A longer beam bridge can be held up along the middle by piers standing in the river. The weight of the bridge itself, plus the load that it carries, plus gravity are the downward forces are spread evenly across the length of the bridge. The upwards forces that hold the bridge up come from the piers. The Confederation Bridge in Canada is a famous beam bridge.
Initially, suspension bridges before 1940 were made of piers, towers, wires, anchorages, and roadways. Piers were the main foundation for the suspension bridges. There usually were two of them, which were made out of cement and were entrenched in ground underneath the body of water that the bridge was spanned across. Towers were built on top of the piers to provide a means of connection for the roadways and wires. Wires were connected to the towers, roadways, and anchorages to provide tension support for the weight of the bridge. The anchorages were large cement platforms that were planted into the ground on either side of the land so that the wires could be connected to it. Lastly, the roadways were the main point of the suspension bridge. They usually were wide enough to provide four lanes of traffic and stretched from one side of the bridge to the other. This was the basic design of the suspension bridges
Arielle: (show drawing) In the end we had made a beam bridge out of hot glue, cardboard and popsicle sticks. We used the cardboard because it is a flat surface and is very light. However, cardboard is not strong enough on it’s own. We then decided to use hot glue to attach the popsicle sticks to the
Since the early days, the men try overcome environmental challenges and, in this process, ends up creating amazing masterpieces of engineering. Among this works, the bridges appears as the clearest representatives of how the mankind could adapt to Earth’s contours. If the shape of landscape can’t be changed, the bridges are the solution to link two places and allows the connection of the traffic to improve aspects such as the communication and the trade. Depending to the need, to the sources and to the environment, the bridge can be constructed in a specific configuration. There are five main sorts of bridges configurations. First, there is the simplest bridge, the beam bridge. Second, the arch bridge, one of the oldest kind. There are the truss, composed of set of trellises. Lastly, there are the cable-stayed and
The Pratt truss bridge was originally founded by Caleb and Thomas Pratt in 1844. It is mainly used to carry trains. The biggest advantage of this bridge was its low costs for construction and the materials to construct a truss bridge are minimal. It also use materials that is cheaper and light in weight. We can easily identify a pratt truss by detecting its diagonal members, which (excluding for the very end ones) all slant down and in toward the center of the span. The pratt truss was designed by applying few laws that related to the mechanics of materials concept. The bridge is mainly built using steel girders to support the construction of the structure. The below part of bridge weight is high so, it need an enough support to prevent from
Hecox (2011) says that the arch structure of the Tillman Bridge makes the canyon walls hold the weight of both vehicles and the bridge itself. In addition, the arch structure allows a better vision of the canyon for the drivers, which was a request of the population to the engineers of the project. In the other hand, according to Jones (2015), the truss structure of the new St. Anthony Bridge also was requested by the population because they wanted to keep a truss bridge in that place. The author also affirms that the St. Anthony Bridge is a truss, but the project team proposed adding a posttensioned concrete bottom chord to the steel truss in order to reinforce it. The project team made this choice because one bridge in Minnesota has collapsed in 2007, and the engineers wanted to lessen the fracture-critical issues to avoid a new catastrophe. In addition, this posttensioning approach wiil make the structure redundant for both resiliency and long-term durability. In conclusion, both bridge's structures were right chosen in order to provide safety and beauty in both
Brunel’s solutions were groundbreaking and critics often questioned his designs. The Clifton Suspension Bridge had the longest span of any bridge in the world when it was completed; the Maidenhead Bridge was both the largest spanning brick arch bridge and the first to use a flattened arch form; and the Royal Albert Bridge was built using lenticular iron trusses.
The most common types are the beam bridges, arch bridges, suspension bridges, cantilever bridges, cable-style, and the kind I am going to research is truss bridge.
The man who drew the designs for the bridge was John Low Waddell. The people of Duluth were eager to build the lift bridge, which would have been about 130 feet wide. However, the War Department declined the design that John Waddell made, and the project was canceled before it could be built. Waddell's design went on to be built in Chicago. New plans were later drawn up for a structure that would bring people from one side to the other. This type of bridge was first demonstrated in Bilbao's Vizcaya Bridge in 1893. The Lift Bridge was then finally completed in 1905. After the history is learned the structure is very important as well to know. The height of the Lift Bridge is 180 feet when completely raised and the length is 386 feet and weighs approximately 900 tons. The bridge is very similar to the only other one of its kind in the world, which is in Rouen, France. The last and most important thing that
The Principle upon which all trusses rely is that the triangle is the strongest and most rigid geometric Figure. By arranging the framework of triangles in patterns that varied from designer to designer, the structure acquired different appearances and served different purposes depending on the needs of bridge builders. The pony truss, the smallest type and ordinarily confined to lengths under 140 feet, with most under 100 feet, is distinguished by its low profile and absence of bracing above the roadway. The through truss by comparison is greater in length and height and consists of a tunnel-like structure that carries traffic through a system of overhead bracing which ties together the upper chords of the bridge.
It is shaped in a way to transfer weight to the towers and anchors with its tension (O'Connor, 1971, p. 372). Cables are made of high strength wires spirally bound to form a rope (O'Connor, 1971, p. 372). Vertical cable suspenders that are fastened to the main cables hang the actual roadway. Stiffening girders and trusses are along the side of the bridge to distribute concentrated loads and help to keep the motion of the bridge at a minimum (Troitsky, 1994, p115).
There are over 30 different types of truss bridges. Though the most common four bridges are the Warren truss bridge, Pratt truss bridge, Howe truss bridge, and K-truss bridge. Out of these four main bridges, our bridge looks similar to the Howe Truss bridge. Our bridge looks like the Howe Truss bridge because our design is similar. A Howe Truss bridge is built with the rods on the side of the bridge crossing each other like an x, which is how we built our bridge.
The bridge that I build in class was a Warren Truss. It turned out to be a decent little bridge. It weighed 21.4 ounces so that put it on the lighter side of the bridges compared to the rest of the class. It wasn’t the lightest, but it was down with the smaller ones. It ended up holding right around thirty pounds and I’d say that not too bad. I knew my bridge was going to be on the lighter side, but I was okay with that because I knew that would maybe help me out in the long run by having a better overall ratio. I didn’t calculate what the ratio actually was, but I think I did alright considering what my bridge weighed and how much it held. It’s kind of crazy that a tiny bridge like that could hold 30 pounds.
A bridge is a structure providing path over an obstacle. When constructing a bridge, obstacle can be a river, railway track or a valley and the path provided by bridge can be for a road, pedestrians, a railway, pipelines, viaducts to carry water from rich areas to dry cities, or for commercial purpose to host commercial buildings such as restaurants and shops. A bridge can also be laid to reduce the distance of travel which in turn reduces the time to reach the destination.