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Building A Waddell A-Truss Bridge

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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 …show more content…

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

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