Team Design of a Pedestrian Truss Bridge: Jessa Marie Zabala, Jasmine Quigley, Abhimanyu Joshi
Introduction: Choosing a Bridge Design
The design brief presented by CIV102 requested the design of a pedestrian truss bridge to span a ravine, a distance of 150 m. The requirements for an aesthetically pleasing design were simplicity and originality. The main objective was to pitch a design that minimized cost, was simple and safe. The detailed design objectives were found to be of more importance in the design of a pedestrian truss. Realizing this our team chose a simple truss design that addressed the needs of those who would be using the bridge. We designed a symmetrical truss (see figure) that would have an inverted truss in the middle allowing passersby to look out over the river while walking or biking. The Detailed Design of a Truss Bridge and the Design Process The detailed design of a truss bridge requires a multitude of calculations to account for all possible conditions. These conditions were given in the form of constraints in the design brief. As a team we started by dividing the calculations amongst ourselves. After doing a set of calculations, we would hand them off to another group member to review our work as a checking process and then proceed, this calculate and check procedure was used throughout the detailed design phase of the truss bridge. Our team was responsible for choosing the dimensions of the steel members that would be used to minimize cost and weight to meet the requirements presented in the design brief. This design project had us constantly going back to the requirements of the given design brief and thinking about how to please our key stakeholders: the pedestrians that would be using the bridge and the client that presented us with the task. The brief was used as a check list to make sure that we'd met every requirement and addressed every criterion to the best of our abilities. The components of the design process used were the constant refining of the work being produced by the team, and always referring back to the requirements set out by the design brief. This was an important exercise for the design team to gain experience in pitching a design to a prospective client. We wanted to address the requirements that we believed were the most important to them because engineering design requires taking into account the needs of the key stakeholders. My Contribution to the Detailed Design of a Truss Bridge
The design of the pedestrian truss bridge for CIV102 was generally a group effort. We met on several occasions to do calculations together, so that we could continue with our checking process and make design decisions as a team. However, we also each took on specific roles as part of the design team to make the process go faster. I was responsible for calculating the member forces in the main truss, the bottom wind bracing, the top wind bracing, choosing the dimensions of the steel of the top wind bracing, and calculating the total cost of our bridge. This allowed for my other group member, Jasmine Quigley, to calculate the dimensions of the steel for the main truss while I continued to calculate the member forces of the next part of our bridge. We worked in an assembly line style, so that when I finished one of my parts, while she did her part of choosing the dimensions, she could check my work. She would also hand her work to me, so that I could check her calculations as well. We found this to be an efficient way of doing a large amount of calculations in a short time without having to compromise on any of the key requirements set out by the initial design brief. |
What Did We Design For?
While designing our truss bridge we focused a lot on designing for safety and designing for cost effectiveness because we felt that those were the most important Dfx's to take into consideration with our key stakeholders. The stakeholders in question were the members of the community board that requested the construction of the bridge and who we were pitching our design to. We also designed for safety keeping the pedestrians in mind who would be using the bridge. Safety was taken into account with the many safety factors that were used during the detailed design calculations and we also made sure that our bridge adhered to standard bridge building codes for British Columbia. The calculation checks we implemented also acted as a design for safety tool because we were constantly rechecking if our calculations made sense and followed the given safety factors. We designed for cost effectiveness by choosing the steel members of our bridge based on whether they could support the load with less surface area, which decreased the cost a lot more. We also took into account, after doing research (that can be found in the report document), that decreasing the number of joints also decreased the amount of maintenance the bridge would require, which also reduced the cost of our bridge in the long run. Lastly we designed for simplicity to not take away from the beauty of the park, and so that passersby could actually see the ravine by inverting our middle truss, but still having a symmetrical shape. Reflections on the Detailed Design of a Truss Bridge This design project taught me a lot about taking into account the needs of the client especially when pitching a design. We learned to first address what was important to the client and what was provided in the brief before incorporating our own personal design decisions. I learned as a designer that it is important when working in a team setting to make decisions as a team before proceeding any further into the design work. This made sure that everyone was on the same page, so that there would be less reproduction of work. I enjoyed this team experience because all our contributions to the task at hand were equally important and they all built off one another encouraging the design process to remain a team effort. Report Document The Report was a collaborative document when it came to the brainstorming of ideas, but it was type written by my group member Abhimanyu Joshi. https://docs.google.com/document/d/14qO1Cg_rVz5CWYNvXaIjO8I9Vi-3eLASwZohXiuIuGk/edit |