Introduction to Engineering - Truss Bridge Design - Essay Example

Number Introduction to Engineering-Truss Bridge Design Affiliation and Address E-mail Truss bridges are the oldest bridge designs that are being used around the world for the transportation of goods as well as people across rivers, lakes and difficult terrains. They have helped human a lot by allowing them to move with access load from place to place easily. Purpose of conducting and developing this project is to design a truss bridge model with given specifications for a bridge competition. The designed model was according to the required results in within the given specifications range. This model successfully worked to hold desired load and effectively fulfilled the load resistance qualities that a practical bridge must have. Keywords Truss bridge, bridge competition, bridge model, bridge stability. Introduction Bridge design is the fundamental part of civil engineering and most critical as well. It is designed for transportation of heavy traffic; meanwhile, it is constructed to cope with environmental effects like storms. There are many types of bridges that are being used around the world, among them most common are arch bridges, girder bridges, truss bridges, cantilever bridges, cable stayed bridges, moveable bridges and suspension bridges(SWE, 2012). The type of bridge that we incorporated in our design is the truss bridge. These are the oldest and the most economical bridges found around the world with excellent weight bearing capacity(BuildingBig, 2010). Atypical truss bridge is shown below: Specialty of truss bridges is the triangular elements present in the structure to share the load applied on the bridge by the traffic(JHU). In a typical truss bridge design the horizontal members are responsible for bearing loads as a result of horizontal as well as dynamic compression. Methodology Materials Used Hot glue gun Popsicle sticks Wood glue Tape Ruler Pen Knife Research Method and Construction of Bridge In our bridge design we made use of Popsicle sticks to create truss members as well as the base of the bridge. These sticks were joined together by making use of glue. Where required, the sticks were cut to the required lengths for making triangle structures of the bridge. For providing strength to the design, the sticks were stacked over each other in 3 to 4 layers and the whole structure was made which is shown below: Before finalizing the above bridge design, we tested a number of bridge structures before as well by making use of west point bridge design, but all those designs failed while testing. By making use of strategic techniques to design practical bridges based on load distribution errors were reduced and thickness of trusses and other members was increased. This gave stability to the bridge design. After that we started working in the structure of the bridge. For that purpose the first task was to select the appropriate material for constructing truss bridge which goes well with our dimensional requirements. Therefore, popsicle sticks were chosen as a preferred material. After that all the sticks were marked at the point of applying glue. Initial step was to design the the bottom frame of the structure in which three layers of sticks were used. Here is the view of one bottom structure. Total two rails were made for the bridge. After structuring the bottom next step was to structure the rectangular truss portion of the bridge. For that purpose first two steps of bottom design were used; to collect popsicle sticks and gluing them together. After that, triangular portions were structured and joined together. These trusses were then connected to the bottom rails as shown below: Last step was to connect the assembly of both the trusses and bottom rails to each other by making use of popsicle sticks and gluing them to the bottom. In this way the final structure was drawn. Results and Discussion In the design of first bridge, total 145 popsicle sticks were used and the resulting weight of the bridge was calculated to be approximately 198.3lbs. The designed bridge was capable of holding 25.86lbs weight which is equivalent to 11730grams. Above that weight, bridge failed to support load and the reason of its failure was the tilt of bridge without breaking. In the final design of bridge, total 170 popsicle sticks were used and the resulting weight of the bridge was calculated to be approximately 249.8lbs. The designed bridge was capable of holding 64.68lbs weight which is equivalent to 29338grams. Above that weight, bridge failed to support weight and the reason of its failure was the tilt of bridge without breaking. The weight on the bridge was applied by connecting hook to the bridge and adding loads to it. Here is the final assembly for checking load resistance of the designed bridge. Although the proposed model didn’t broke by applying heavy loads but the tilt in bridges is also not a positive mark while developing a design model. Therefore, bridges designed must not be tilted even at high loads. For that purpose more expertise is required in this field. Another factor that added to this failure was the quality of popsicle sticks. The popsicle sticks used in our design were of medium quality, by making use of good quality sticks bridge design can be improved in terms of weight bearing characteristics. Conclusion By developing a truss bridge for bridge competition, we learned a lot about designing and developing a civil engineering project. In the first design of the bridge, we made use of lesser number of popsicle sticks which made our design weaker. By introducing more number of sticks to the design, the bridge became better at final stage and it was done by making top and bottom of the bridge stronger. Another factor that really affected the design stability was the regularity of truss members. Truss members must be equal spaced and placed in the same pattern along the bridge and it helps in adding more stability to load bearing and fatigue characteristics of the design. References BUILDINGBIG 2010. Bridge Basics. JHU Bridge Designer. SWE. 2012. Bridge Construction [Online]. Available: http://www.swe.org/iac/lp/bridge_03.html. Read More