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Suspension vs. Cable-Stayed Bridge Strength

Medium
Suspension vs. Cable-Stayed Bridge Strength | Science Fair Projects | STEM Projects
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.

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