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Warren Truss (with verticals) vs Pratt Truss Bridge
Edward Medrano
John Jay Science & Engineering Academy
PurposePurpose: To determine if a Warren Truss bridge ( with verticals) can hold more than a Pratt Truss bridge,
Engineering Goal Engineering Goal: To build and test Warren Truss bridges
(with verticals) and Pratt Truss bridges to determine which
bridge design is the strongest.
Background Information● A popsicle stick bridge is a simple bridge structure that
anyone can design and create in their home, school or at work.
● Triangles are known as the best shape for any structure.● Popsicle stick bridges can be made either from regular
sticks, or they can be cut into smaller pieces so that more elaborate designs can be achieved.
● Large and more elaborate popsicle bridges can withstand the weight of over 3,000 pounds.
Materials● Popsicle sticks● Elmer’s glue● Binder clips● Bridge testing machine
Procedure1.1,000 popsicle sticks were bought from Walmart.2.Elmer’s glue was bought from Walmart.3.Truss shapes for bridges were made with popsicle sticks and Elmer’s glue.4.The floor platform of the bridge was assembled.5.Truss sides were attached to floor platform.6.Roof of the bridge was built and added to the trusses.7.This process was repeated 10 times for each type of bridge.8.The testing was done in sets of 1-2 bridges a day.9.The data was recorded into a journal/spiral.10.The data was entered into a google sheet for analysis.
Table 1: Warren Truss Bridge (with verticals) Load Test Trial Data
Trial # Bridge Type Bridge Tensile Test (lbs.)
1 Warren 113
2 Warren 101
3 Warren 141
4 Warren 155
5 Warren 131
6 Warren 149
7 Warren 123
8 Warren 159
9 Warren 169
10 Warren 157
Table 2: Pratt Truss Bridge Tensile Test Trial Data
Trial # Bridge Type Bridge Tensile Test (lbs.)
1 Pratt 186
2 Pratt 188
3 Pratt 195
4 Pratt 179
5 Pratt 155
6 Pratt 132
7 Pratt 193
8 Pratt 197
9 Pratt 213
10 Pratt 149
Table 3: Bridge Average Tensile Test Results
Warren Average Bridge Tensile Test (lbs.) Pratt Average Bridge Tensile Test (lbs.)
139.8 178.7
Count Count
10 10
Conclusion ● The engineering goal of this project was achieved by building and
testing the Warren Truss and Pratt Truss bridges to determine
which bridge design was the strongest.
● The average load of the Pratt truss bridge was 178.7 pounds
compared to the warren truss’s average load of 139.8 pounds.
● The results could have been affected by construction errors.
● The bridge may have been uneven.
● The testing weight may not have been perfectly centered.
Further Applications● The data collected from this project can be used by structural
engineers to improve current bridge designs.● The data can be used to create new bridge designs.● This project data can inspire civil engineers to build better
bridges.
Further Studies● More of each bridge could be made and tested.● More and different bridge designs could be constructed and
tested.
Warren vs Pratt Truss Bridge