Prestressed concrete

1. Prestressed Concrete Concepts: Prestressed concrete strengthens against tensile forces Tensioning of highstrength tendons improves performance Characteristics of highstrength concrete and steel Internal stresses are introduced in a planned manner Used in highrise buildings, bridges, and industrial structures 2. Pretensioned Concrete Concepts: Tendons are tensioned before concrete casting Strong endanchorage points are required Bond strength between concrete and tendons is critical Tendons generally form straight lines between anchorages Used for structural beams, floor slabs, and water tanks 3. Posttensioned Concrete Concepts: Tendons are tensioned after concrete casting Tendons are encapsulated within protective sleeves Large forces are required to tension the tendons Different anchorage systems are used based on tendon composition Tendon encapsulation systems are made from plastic or steel 4. Bonded and Unbonded Posttensioning Concepts: Bonded Posttensioning: Tendons are permanently bonded to surrounding concrete Grouting protects tendons against corrosion Bundling of elements inside a single tendon duct is common Improves structural behaviors of the final concrete structure Used for efficient tendon installation and grouting processes Unbonded Posttensioning: Tendons are not bonded to surrounding concrete Tendons are encapsulated within a greased sheath Reaction forces from tendon profiling counter loadings Ducts/sleeves can be profiled to any desired shape Beneficial for countering loadings applied to the structure 5. Applications and Notable Structures: Applications of Prestressed Concrete: Versatile in construction with highstrength steel and modern concrete Used in major design codes for various structures like buildings, bridges, dams, and pavements Utilized in stadiums, silos, tanks, and other civil structures Notable Structures: Examples include the Sydney Opera House, CN Tower, and the Gateway Bridge Also used in the construction of LNG tanks, nuclear reactor vessels, and blastcontainment walls Various organizations worldwide promote best practices in prestressed concrete design and construction This organization groups similar concepts together for a more structured and comprehensive understanding of prestressed concrete technology and its applications.