The Effect of Bridge Design on Bridge Weight Bearing Capacity

Overview

Objectives/Goals This project tested to see whether a Pratt truss or a Warren truss would hold more weight. The researcher's hypothesis was that the Pratt truss would hold more weight. Methods/Materials In this experiment, the researcher built both types of trusses out of popsicle sticks. Each one was placed, one at a time, in a testing device made of plexiglass and wood. Iron weights were then placed into a bucket that was attached to the bottom of the truss. Sand was slowly poured into the bucket until the truss failed. The project contained 50 total trials, 25 trials for each truss. Results The results of these trials showed that the Warren truss held an average weight of 35.16 kilograms, while the Pratt truss only held an average weight of 32.03 kilograms. The range of weight held by the Warren truss was 35.35 kilograms. High and low outliers were detected in these results, however, with a maximum weight of 50.85 kilograms and a minimum weight of 15.5 kilograms. For the 25 Pratt truss trials, the range of weights held was 14.63 kilograms with no outliers detected. Conclusions/Discussion The findings did not support the researcher's prediction. Where the Warren truss held more weight on average, the Pratt truss was more consistent. In the real world, engineers could use these findings to determine which truss design to use when building a bridge.

Awards (1)

• Category Award

Competition history

• CSEF 2006 Structural Capability & Strength of Materials (Junior Division Only) · Entry J1804

Resources

• CSEF project summary ↗

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