Truss bridge
The objective of this project was to design and construct a bridge using a truss formation of our choice, built from coffee stirrers. Working in a team of three, we collaborated to develop a structurally sound design. To challenge myself, I imposed the additional constraint of not cutting any of the stirrers, which led me to explore formations such as the K-truss and the Bowstring truss, both of which influenced the final design.
The assembly process proved to be one of the most demanding aspects of the project. Given that we were limited to PVA glue, drying times significantly impacted progress, requiring each member to carefully hold components in place as they set to prevent structural misalignment. To enhance the bridge’s integrity, I reinforced key areas by doubling up stirrers while ensuring we adhered to the 150-stirrer limit.
For the structural testing phase, the bridge was suspended between two tables and incrementally loaded with bricks and slabs. It withstood 7.1 kg before failure. As a team, we worked together to construct and test the bridge, while I led the structural analysis, assessing the stress points and failure mechanism.
Upon analysing the snapping point, it became evident that structural failure occurred due to insufficient reinforcement in that area. However, given the material constraints, additional strengthening at the time was not possible. Moving forward, I would refine the weight distribution strategy, shifting reinforcement from the sides to the top and bottom chords, improving the overall load-bearing capacity.
Technical Skills:
Structural Analysis & Problem-Solving – Led the assessment of stress distribution and failure points in the bridge, identifying areas for reinforcement and future improvements.
3D Modelling & Design Development – Explored various truss formations, such as the K-truss and Bowstring truss, to inform the final bridge design, ensuring structural integrity while adhering to material constraints.
Precision Model Making & Construction – Collaborated in a team of three to construct the bridge, navigating assembly challenges such as prolonged drying times and alignment accuracy while reinforcing key load-bearing areas.
Material Efficiency & Engineering Constraints – Worked within a strict 150-stirrer limit, optimising material placement to enhance the bridge’s strength without exceeding constraints.
Load Testing & Evaluation – Participated in controlled testing, incrementally applying weight until failure, and documented key findings to refine future designs.
Full analysis below:
Full Bridge Evaluation and Stress Analysis
