ENGINEERING – TRUCTURAL ENGINEERING — CONCRETE CALCULATOR
Prestress Loss Estimate
A precise tool.
What is the Prestress Loss Estimate & How does it work?
Prestressed concrete members lose a portion of their initial force over time due to several mechanisms. The elastic loss occurs immediately after tensioning as the concrete shortens under the applied stress, while creep loss develops gradually as concrete deforms under sustained load. Shrinkage of concrete, caused by moisture loss, further reduces the effective prestress, especially in the early months after casting. Relaxation of the steel strands or tendons, a time‑dependent reduction in stress under constant strain, adds to the total loss and must be accounted for in long‑term designs. Accurate estimation of these losses enables engineers to size tendons and select appropriate tensioning schedules, ensuring that the structure retains the required serviceability and strength throughout its lifespan.
\Delta P = P_{0}left(\varepsilon_{el}+\varepsilon_{cr}+\varepsilon_{sh}+\varepsilon_{rel}right)
\Delta P = total prestress loss (kN)
Parameters
Result
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Frequently Asked Questions
What causes prestress loss in concrete?
Prestress loss occurs due to elastic shortening of concrete, gradual creep under load, moisture-induced shrinkage, and relaxation of steel strands over time.
How does elastic loss affect prestressed concrete?
Elastic loss happens immediately after tensioning as the concrete shortens under applied stress.
What is creep in the context of prestressed concrete?
Creep refers to the gradual deformation of concrete under sustained load over time, leading to a reduction in effective prestress.
How does shrinkage affect prestress in concrete?
Shrinkage, caused by moisture loss from concrete, reduces its volume and contributes to prestress loss, especially in the early months after casting.
What is steel relaxation in prestressed concrete?
Steel relaxation is a time-dependent reduction in stress within the steel strands or tendons used in prestressed concrete members.
How can I estimate prestress loss over time?
Use this calculator to input initial prestress values and relevant parameters to estimate losses due to elastic deformation, creep, shrinkage, and steel relaxation.
Why is it important to account for prestress loss in concrete design?
Accounting for prestress loss ensures that the structural integrity and durability of prestressed concrete members are maintained over their service life.
Results are for informational purposes only and do not constitute professional advice.