
Suspension vs. Cable-Stayed Bridge Strength
Medium
Does a suspension bridge or a cable-stayed bridge hold more weight before it breaks? Both designs use cables but connect them to the towers in different ways.
You build scale models of each type from balsa wood and twine. A basket hangs from the center of each bridge. You add weights one at a time until the bridge fails.
The cable-stayed bridges held nearly twice the weight. One cable-stayed bridge never broke at all. A suspension bridge collapsed right after a single cable snapped.
Hypothesis
The hypothesis is that a cable-stayed bridge will support more mass than a similar built suspension bridge.
Method & Materials
You will build two bridges, a suspension bridge and a cable-stayed bridge, and attach a basket to the middle of the bridges with a harness to support the mass. You will then fill the basket with weights one at a time until the bridge breaks.
You will need 4 balsa wood strips, 4 wood dowels, glue for models, lightweight twine, fishing string, and small weights.
Results
The results showed that the cable-stayed bridges held more mass than the suspension bridges. One suspension bridge broke immediately after one of the vertical suspension strings snapped. The first cable-stayed bridge never broke with the full mass on it.
Why do this project?
This science project is interesting because it tests two different types of bridges to see which one can hold the most weight.
Also Consider
Variations to consider include testing different materials for the bridges, such as metal or plastic, or testing different lengths of bridges.
Full project details
Additional information and source material for this project are available below.Related video
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
Share this Science Project:
Related Science Fair Project Ideas
Pour water loaded with leaves, grass, soil, and plastic over flat and dome drain covers to see which one stays clear.
Medium
Build three model bridges with different side coverings and measure which one tilts the most in crosswind from a fan.
Medium
Drop a sandbag into a water tank to create a wave and measure whether a wall or an artificial mangrove swamp blocks it better.
Medium
Share this Science Project:
