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Growth in the Demand for Prestressed Concrete Bridges

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Growth in the Demand for Prestressed Concrete Bridges. FORWARD. GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES.

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slide2

GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • The single most important event that led to the dramatic launch of the precast prestressed concrete industry in North America was the construction of the technically innovative, historically fascinating Walnut Lane Memorial Bridge in Fairmont Park in Philadelphia, Pennsylvania in 1949 and 1950.

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • At that time, manufacturers had no experience with linear prestressing, and little published information was available. This prestressed concrete bridge became a reality because of the vision, persistence and courage of a few extraordinary individuals.

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • One was Professor Gustav Mangel from the University of Ghent in Belgium.
  • He described the concept of pre-compressed concrete to his students using his well-known illustration of a stack of books…

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • The books on the bottom are like pre-compressed concrete: using a compressive force, they support their own weight… plus significant superimposed loads, represented by the books on top.

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • The combination of high strength steel – to resist tensile stress – and concrete – to provide compressive strengthand durability – make this composite material adaptable to many situations, especially the design and construction of bridges.

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • A number of technological innovations followed the success of the Walnut Lane Bridge, including the establishment of precasting plants and in-plant pretensioning…

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • … and the development of 7-wire strand to replace individual wires.

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

Long-Line Casting Beds

Permanent Steel Forms

Admixtures

High Early-Strength Concrete

Accelerated Curing

  • Other early innovations included long-line casting beds; high-quality, permanent steel forms; specialized chemical admixtures; high early-strength concrete; accelerated curing with heat; and more…

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

  • Continuous growth in the use of precast, prestressed products has led to new designs and applications in bridges… and many other impressive structures.

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total bridges built 1950 present
The growth in the demand for prestressed concrete bridges has been nothing short of remarkable. Since 1950, some 108,000 prestressed concrete bridges have been built.

This represents 30% of all bridges built during the period.

GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

Total Bridges Built1950 - Present

30%

108,000

PrestressedBridges

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

Bridge Construction1990 - 1999

Prestressed Concrete:

  • From 1990 through 1999, more than 48% of all bridges built have used prestressed concrete. Even more notable, prestressed construction represents 60% of all state highway bridges and 62% of bridges on numbered U.S. highways.

48% of all bridges

60% of state highway bridges

62% of numbered highway bridges

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GROWTH IN THE DEMAND FOR PRESTRESSED CONCRETE BRIDGES

Deck Surface Area1990 - 1999

Prestressed Concrete:

  • Now, consider the deck surface area of bridges built from 1990 through 1999.60% of the area of bridge decks were built on prestressed concrete superstructures. A further breakdown of deck area built on prestressed concrete superstructures shows 62% of bridges on city streets, 53% of county highway bridges, 55% of interstate highway bridges, 66% of bridges on state highways, and 59% on U.S. numbered highways.

60% of deck area of all bridges

62% of area of city bridges

53% of area of county bridges

55% of area of interstate bridges

59% of area of U.S. numbered bridges

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