Popsicle Stick Bridge!

The Bridge Blog!

We set out to build a bridge that would meet the requirements for our bridge lab!

We started out by planning a strategy/design for our bridge build, which we created in the form of sketches and labels:

Build Process – Nihal

We built the bridge in a number of separate “modules” and assembled them together as needed to build the final product. Our bridge was designed to be two symmetrical halves that were connected by beams to hold them together. For example, each of the two legs of the bridge consisted of a two flat reinforced frames that were connected by a bundle of sticks into a box-like shape. To connect these legs to the truss-reinforced load-bearing segment, we included slots in these legs so we could slide the main beam in, maximizing contact area for glue.

First, we built four mostly identical leg frames separately. While the glue was setting, we designed and built the main beam in two separate flat halves. Finally, once all the pieces were ready, we slotted the halves of the beam into special gaps made in the legs designed to create a large contact surface area to provide maximum grip with the wood glue.

Quantitative Analysis– Quinn

Our bridge was 452g (0.996 lbs), just over a gram shy of a full pound. It successfully held 70 lbs, and collapsed after adding an additional 25 lbs (for a total of 95 lbs). This means that the bridge was able to support somewhere between 70.2 and 95.3 times its own weight.The bridge was 50 cm by 10 cm underneath, with 20 cm vertical distance to the roadway and that the roadway was 60 cm long by 10 cm wide.

Written Analysis– Ian

The bridge held up reasonably well and had a reasonable mass to mass held ratio but the bridge did have one major flaw, the lacking of struts in between the two sides of the bridge. As can be seen in the pictures the bridge itself was still mostly intact after being crushed, it was just that it had twisted and crushed sideways, rather than top to bottom as it was made to withstand. With an increased amount of side struts this problem could have been avoided and the bridge could have held a considerable amount of weight more, because as can be seen in the photos the structure for supporting straight down weight was barely damaged, if at all.

Who did what
We all contributed to building the bridge, but Ian spent extra time building at home to help keep us on schedule. We all also spent a day discussing design and structure of our bridge so we had a clear idea of what to build before we built it. All of us split the work equally for the blog post, each of us writing a section and looking over the other sections (ian did written analysis, Nihal did strategy and quinn did quantitative) .

 

Stages of Building!

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