The pedestrian bridge was an engineering design project in which I was able to apply design process and philosophy to a physical, practical problem. Our design team chose a warren truss, as shown in figure #1, under the premise of it being a powerful yet simple design that could bear a large amount of load with few members. As also shown in figure #1, the bridge is subdivided into three spans of 40-70-40, with columns in between each span. This design decision was made while doing sample calculations to see if a 150m span bridge would be possible (understanding the problem): however according to our investigation, the forces are simply too high in magnitude towards the center of the truss. Most design decisions like the height and railing being based off previous designs seen in class, i.e. the general rule of thumb that the height should be 1/10 the span. We designed our bridge mostly for manufacturability and cost, choosing the same members for the top and bottom chord as buying in bulk is more efficient, while choosing members in the diagonals with the smallest possible area.

 

Again, here there were problems with looking at multiple solutions: Once I saw this solution I just went with it instead of considering other possible designs that may have been better, even though I was still meeting all the imposed requirements and came up a design that could actually bear the required weight. If there had not been time constraints, there would be more interation and careful refinement to our final design, such as making the middle section of the bridge a warren deck to allow the pedestrians to view the environment or perhaps considering other truss designs that would be most suitable for this span. However, there were no problems in prototyping a bridge with correctly sized dimensions that met the cost and safety requirements.

 

 

 

 

 

 

Figure #2: Shows a sample page of the calculations done (by me) for the bridge