By Savannah and Sophie Block 5 Design Brief

Objectives Statement of Inquiry: How do design limitations encourage creativity.? What is the objective? The objective of this project is to make the strongest bridge with 75 popsicle sticks, 3 sticks of glue, and a partner. The group’s bridge that holds the most weight wins. Global Context: Scientific and technical innovation Related and key concepts: Development and resources Bridge Design Requirements: Minimum Span 30cm Minimum 1 popsicle stick width Maximum 20 cm superstructure Maximum 20 cm substructure Maximum 75 popsicle sticks Maximum 3 hot glue sticks

Inquiry and Analysis Triangles are very strong shapes Arch bridges are the strongest type of bridge The longer the span of the bridge the less weight it holds Stone slabs are a very strong material for short bridges Commonly used materials are metal, wood, and stone Triangles are one of the strongest shapes there are because when a load is applied to the apex of the triangle, it evenly distributes the weight down the sides of the triangle. For example, if there is one kilogram of weight applied to the apex of the triangle, then 0.5 kg would be distributed down the two sides of the triangle. Resulting in less compressive force and no damage to the structure.

Inquiry and Analysis : Types Of Forces Type of force What is it? Compression A force that pushes together on opposite sides Tension A force that pulls from either side Torsion A force that twists Deflection The act or force of being deflected

Developing Ideas - Designs And Sketches We decided to do our version of the Pratt bridge. We thought it was the strongest structure because it has lots of triangles and the popsicle sticks were dispersed efficiently and evenly.

Creation Process To start our bridge we needed a strong foundation. We stacked 2 layers of popsicle sticks to make it that much stronger. To make the bridge hold more weight we put the popsicle sticks vertically instead of horizontally. If we did lay the sticks horizontally, they would be very flimsy. After we made the base, we started to construct the superstructure.

Waddell A Truss Pros Cons Environmentally friendly Heavy Can be built anywhere Takes up a lot of space Easily constructed We didn’t choose this bridge because our popsicle sticks did not allow us to make a Tall beam across, that was sturdy as well. It would’ve taken more popsicle sticks then We were supplied with.

Camel back Pros Cons Evenly distributes weight Takes up too much space Wastes materials Heavy Weight We decided not to choose this design because it would use too many popsicle sticks and judging by the chart above, there are more pros than cons. It would be very difficult to build this structure because it’s very big and the top popsicle sticks would have to be glued at just the right angle.

Arch bridge Pros Cons Resistant to compression forces Span is limited Can be made of many materials Build time is lengthy Becomes stronger over time Can crack easily We decided not to choose this bridge because it would take up too many popsicle sticks and it would be hard for us to make the span 30cm. It would also be very difficult for us to construct the round part of the bridge.

Pratt Bridge Pros Cons Simple design Less stable when it comes to vertical loads Cost effective structure Cannot hold greater loads with longer spans Strong history of short span success We decided to build this design, because it’s a very strong structure with a simple but effective design. It was designed with lots of triangles so the structure will divide the force of the weights nicely.

Team Goals Our goals: Make a sturdy bridge Hold at least 70 lbs Use class time efficiently Even out the tasks for the projects How we’ll achieve these goals: Work hard during class and ignore distractions Plan out our bridge design properly

Evaluation – Testing day! We thought that our bridge would hold around 70 pounds of weight. So we started with 5 pound weights and gradually added more. We decided to put our bridge upside down because it was stronger that way. The base we made included 5 layers of popsicle sticks. Resulting in that the top truss chord being the strongest part of the bridge.

Result The result of testing concluded with our bridge holding 70 pounds. We tied for first in our class.

Evaluation Our bridge broke right down the middle. This was because there was the most compression force pushing where the chain was suspended. How could we avoid this problem? We could’ve avoided this problem by adding morePopsicle sticks for even more support. We also could’ve designed our bridge to distribute out the load more evenly.