Warren Truss (with verticals) vs Pratt Truss Bridge

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