Designing the Matboard Test Bridge
Team Members: Matt Yao, Bruce Hu, and Omar Khan
Process
This design project, proposed by professor M.P. Collins of the University of Toronto, required the design team to design and build a bridge made from matboard that spanned 990mm and is able to withstand two point loads at 300mm from the ends. The team was given the shear stress and yield stress of the matboard materiel.
The first step to the design was for the team to decide on the type of beam that we would design. It was a known fact that the higher moment of inertia yielded a stronger bridge, but deciding on the exact height to make that possible came as a design challenge. In order to solve this, we decided to confront upper year engineering science students to tap into their experience designing the same bridge year(s) earlier. From this communication we, the design team, decided that the height of the beam would be 180mm long. The second decision that was to be made is which type of beam we would choose. After brainstorming we concluded that the pi beam would offer the most stability to the bridge while also maintaining a high moment of inertia. However, we realized, that we no longer had enough material to create diaphragms in the beam to protect from shear stresses. For this we decided to cut back on the height of the diaphragms instead of lowering the moment of inertia by compromising the height of the beam itself.
After performing the calculations for shear, buckling, and plate buckling, the design team deemed the design stable and we started building the bridge. At the performance however, we experienced a surprising result. The beam had failed where we would not have predicted. Since our diaphragms were not full height, the bridge buckled at the supports. From this I learned that even though the calculations for the design might seem perfect, the building of the design itself yields space for error as well. Thus, in order to reduce this error, the creation of a physical prototype would have helped with the design process.
This design project, proposed by professor M.P. Collins of the University of Toronto, required the design team to design and build a bridge made from matboard that spanned 990mm and is able to withstand two point loads at 300mm from the ends. The team was given the shear stress and yield stress of the matboard materiel.
The first step to the design was for the team to decide on the type of beam that we would design. It was a known fact that the higher moment of inertia yielded a stronger bridge, but deciding on the exact height to make that possible came as a design challenge. In order to solve this, we decided to confront upper year engineering science students to tap into their experience designing the same bridge year(s) earlier. From this communication we, the design team, decided that the height of the beam would be 180mm long. The second decision that was to be made is which type of beam we would choose. After brainstorming we concluded that the pi beam would offer the most stability to the bridge while also maintaining a high moment of inertia. However, we realized, that we no longer had enough material to create diaphragms in the beam to protect from shear stresses. For this we decided to cut back on the height of the diaphragms instead of lowering the moment of inertia by compromising the height of the beam itself.
After performing the calculations for shear, buckling, and plate buckling, the design team deemed the design stable and we started building the bridge. At the performance however, we experienced a surprising result. The beam had failed where we would not have predicted. Since our diaphragms were not full height, the bridge buckled at the supports. From this I learned that even though the calculations for the design might seem perfect, the building of the design itself yields space for error as well. Thus, in order to reduce this error, the creation of a physical prototype would have helped with the design process.