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Why can prestressed concrete make a bridge lighter and less expensive?
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bridge
The multiple-span Seto Great Bridge over the Inland Sea, linking Kojima, Honshu, with Sakaide, Shikoku, Japan.
Prestressed concrete allows for lighter and more cost-effective bridge designs by fundamentally changing how the material handles structural loads. While concrete is naturally strong in compression, it is weak in tension. By using high-strength steel tendons to place the concrete into a state of permanent compression, engineers can effectively counteract the tensile stresses caused by applied loads.12
This technology offers several advantages:
- Material Efficiency: Because the compressive stress offsets the downward load, less concrete and steel are required compared to traditional reinforced concrete designs.2
- Reduced Depth: Prestressed concrete allows for shallower girder depths, which reduces the overall volume of material needed.32
- Construction Savings: Techniques such as the cantilever method can eliminate the need for expensive scaffolding in water, further lowering costs.3
Ultimately, these factors result in lighter, more elegant structures that can span greater distances while remaining economically competitive with steel.132