Wooden Truss Bridge

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

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.

Suspension bridges were important before 1940 and are still important today. Major cities such as San Francisco, and Manhattan both have a suspension bridge. Suspension bridges are,” a bridge having a deck suspended from cables anchored at their extremities and usually raised on towers” (dictionary.com). Due to the fact that suspension bridges are not completely supported throughout the length of the bridge, past bridges were unsafe. For example, the Tacoma Narrows Bridge was a suspension bridge opened on July 1st, 1940 (Mark Ketchum). This bridge marked a huge point in suspension bridge safety and engineering, because in collapsed approximately four months after it was opened (Parsons). The collapse caused such a shock, that suspension

Calculations were performed to determine the effectiveness of the design of the platform. Allowing for a safety factor of 1.5 times the design weight of 10kg and considering the bridge must not be overdesigned; plans were made for the bridge to fail at 25kg, 2.5 times that of the design weight. According to the calculations, the bridge would hold a load of over 15kg and experience failure at 20kg in the members. These calculations were later disproven in the testing, breaking 8kg earlier than expected, due to unforseen errors. An analysis of the bridge design and calculations has been included at the end of this report.

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

Truss bridges have been around for a long time. I see truss bridges the most out of all the different types of bridges and to me it seems like the most popular type of bridge. In addition there are thirty different types of Truss bridges which means that there is a bigger variety of Truss Bridges instead of just having one type. Truss bridges have triangular shaped beams that go all across the bridge. The bridge also is above the roadway instead of under the roadway like the arch bridge. Truss bridges could also stretch very far. The longest cantilever Truss bridge that goes is called Crescent City Connection and it is 13,418 feet long with a width of 52 feet. There is also a really long Truss bridge that is near Hoboken, the name of the bridge

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

In the initial stages of it’s evolution, the truss takes the form of a king post a simple triangular shape, usually composed of timber with iron hardware, divided by a single vertical post connecting top and bottom chords. You can make the Warren truss

The purpose of this report is to introduce the roof truss that I had designed for the project of design studio 1 which is personal space. I have included the following content for the design: characteristics, cons and pros, sketch and label, and cross section of the design. The roof truss that I had design for the personal space building is king post truss (also known as crown post truss). According to online dictionary, the definition of king post is a structural member running vertically between the apex and base of triangular roof

The initial design of the truss bridge shows trusses that are symmetrical throughout the bridge which allowed the weight of the truck moving across to be spread evenly throughout the bridge, allowing it to be stable when the weight is added resulting in minimal deflection of the overall bridge. Throughout the process, most supporting beams were mainly solid bars as they are good in tension and are more sturdy giving the bridge stronger structure. Other beams that didn’t take much load were changed to hollow tubes to lower the cost as well as hold the tensile load of the bridge, this overall reducing the cost and making the bridge more sturdy.

The general triangular shape of a truss has been in use since man has used lumber for construction of structures. The origin of the triangular shapes of a truss stem from early roof design, when wooden roofs were constructed in a triangular shape. Within the triangular frame, a post was placed in the midspan of the bottom member of the frame which connected to the peak of the angled member on the top (see Figure 1.) If the roof had a wider span or lower pitch, rafter were placed at

most bridges are steady bridges, this means that they have no shifting components and stay in one area till they fail or are demolished. Temporary bridges, which includes Bailey bridges, are designed to be assembled, and taken aside, transported to a awesome website on line, and re-used. They may be vital in military engineering, and also are used to carry website online visitors even as an vintage bridge is being rebuilt. Movable bridges are designed to transport out of the manner of boats or other varieties of site visitors, which would possibly in any other case be too tall to healthful. Those are typically electrically powered.

The Tacoma Narrows Bridge is perhaps the most notorious failure in the world of engineering. It collapsed on November 7, 1940 just months after its opening on July 1, 1940. It was designed by Leon Moisseiff and at its time it was the third largest suspension bridge in the world with a center span of over half a mile long. The bridge was very narrow and sleek giving it a look of grace, but this design made it very flexible in the wind. Nicknamed the "Galloping Gertie," because of its undulating behavior, the Tacoma Narrows Bridge drew the attention of motorists seeking a cheap thrill. Drivers felt that they were driving on a roller coaster, as they would disappear from sight in the trough of

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.

Superstructure bears the load that is being passed over the bridge and it transmits the forces caused by the same to substructure. Load received from the decking is transferred on to the substructure by Bearings. They also distribute the load evenly over the substructure material as it may not have sufficient strength to bear the superstructure load directly. Piers and Abutments are the vertical substructures which transfer the load to the earth in the foundation. Wing walls and returns are constructed as the extension of