Truss Design Challenge Experiment - Group 3

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For this challenge, students in the lab were tasked with designing a truss or bridge to span a specific distance and resist a 100 lb load in a four-point flexure test. All the requirements for the bridge are clearly outlined below: • Span length of 400 mm • Width of 75 mm • Maximum height of 75 mm • Maximum weight of 100 grams • Must hold 45 kg (100 lbs) • No adhesion (glue, etc.) for connections The challenge for students in this experiment was that their bridge had to be printed in separate parts because the bridges were too large to print all at once. Students had to design connections for these parts without using glue or other adhesives. The connection design was critical because it is the weakest point on their trusses. Information on Group 3's Bridge: This is the design from Group 3 in the laboratory. Their truss design is commonly known as a Warren Truss. This group kept their design simple with a total of three parts. They designed their lateral connection (the "connector and middle connector" file) to hold the truss together to resist normal and shear forces acting along the connections, and to resist overturning laterally. The bridge had a total weight of 102 grams and resisted a load of 81 lbs before failure. The bridge failed due to overturning laterally at the center of the truss. To improve their design, the group recommended using cross bracing at the center instead of straight line connections. Note: The handout for this challenge will be available soon. I will provide a link to the handout in this description when it is complete, so you can perform this experiment yourself or with your students.