Truss Design: The Steps To Designing A Bridge Lab Project

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Introduction: The bridge lab project was based on the given scenario in which a reliable bridge needed to be constructed over a river in order to alleviate traffic. The objective was to design a bridge to relieve traffic flow that was also safe, cost effective, and aesthetically pleasing. The constraints for this project included the budget and minimum height and width requirements. The max budget to purchase wood was $200, the minimum height at all points of the bridge was 3 inches, the minimum width of the bridge was 4 inches, and the final bridge had to accommodate a 3”x 3” platform in order to test bridge deflection at the end of construction. The following lab report shadows the steps for design evaluations by providing background information, …show more content…
Critical criteria, which was used to evaluate and choose a design, included the least expensive and safest design within the size requirements (see Appendix 2, Page 1). Truss Design 2 was a Howe Truss, which has triangles for a stable framework. This type of truss was chosen to reduce the amount of wood for needed construction, which reduced the cost (Ward, slides 3 and 5). The design (see Appendix 2, Page 2) was originally created to span across the widest section of river, about 12 in.s. The design optimization process (see Appendix 2, Page 3) revealed that the most optimum distance (traffic score) was 8.422415 in., would cost $137.5625 (see Appendix 2, Page 4), as well as earn a safety and aesthetic score of 0.043432 and 6.878127 respectively. These calculations were used to help redesign the best bridge. The resulting design (Appendix 2, Page 5) received a total score of 452, which matched the total score given by the design optimization process. The vertical beam in the middle of both sides of the bridge, from Truss Design 2, was taken out of the final design to reduce the cost to allow for extra wood to help construction. In addition to the center beam, the finalized bridge design’s base length was reduced to nine inches and the top’s length was reduced to six inches. The width and height of the final bridge design remained the same, due to the requirements listed …show more content…
That design was then optimized for the final score in order to determine the ideal contour score are maximum deflection score. After examining the outcome of the bridge, the design could have been improved by adding additional supporting members at intervals between the top and bottom portions in order to distribute the force from the 3”x 3” platform straight down as well as to the side sloping members. Another solution would have been to alter the design and have the bridge shaped more like a rectangular prism than a trapezoidal prism by changing the connections from the top and bottom portions to meet at 90 degree angles instead of the 63.4 degree angles. Future bridge designers should take note to predict the forces that act upon the bridge members and act accordingly by disbursing the forces evenly. They should also use precision in building in order to produce clean connections between members. The bridge design project taught the importance of precision, both in construction and in engineering design accuracy, distribution of total force, and the engineering design method in

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