Prestress Drop Calculator

✖Modulus of Elasticity of Steel Reinforcement is a measure of its stiffness.ⓘ Modulus of Elasticity of Steel Reinforcement [E_s]			+10% -10%
✖Change in Strain is the train change in the tendons used in prestressed member.ⓘ Change in Strain [Δε_p]			+10% -10%

✖Prestress Drop is the drop in applied prestress force due to strain in tendons.ⓘ Prestress Drop [Δf_p]

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Formula

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Prestress Drop

Formula

`"Δf"_{"p"} = "E"_{"s"}*"Δε"_{"p"}`

Example

`"10MPa"="200000MPa"*"0.00005"`

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Prestress Drop Solution

STEP 0: Pre-Calculation Summary

Formula Used

Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Change in Strain
Δf_p = E_s*Δε_p
This formula uses 3 Variables

Variables Used

Prestress Drop - (Measured in Megapascal) - Prestress Drop is the drop in applied prestress force due to strain in tendons.
Modulus of Elasticity of Steel Reinforcement - (Measured in Megapascal) - Modulus of Elasticity of Steel Reinforcement is a measure of its stiffness.
Change in Strain - Change in Strain is the train change in the tendons used in prestressed member.

STEP 1: Convert Input(s) to Base Unit

Modulus of Elasticity of Steel Reinforcement: 200000 Megapascal --> 200000 Megapascal No Conversion Required
Change in Strain: 5E-05 --> No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

Δf_p = E_s*Δε_p --> 200000*5E-05

Evaluating ... ...

Δf_p = 10

STEP 3: Convert Result to Output's Unit

10000000 Pascal -->10 Megapascal (Check conversion here)

FINAL ANSWER

10 Megapascal <-- Prestress Drop

(Calculation completed in 00.004 seconds)

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Home » Engineering » Civil » Structural Engineering » Prestressed Concrete » Losses of Prestress » Loss due to Elastic Shortening » Post-Tensioned Members » Prestress Drop

Credits

Created by Chandana P Dev

NSS College of Engineering (NSSCE), Palakkad

Chandana P Dev has created this Calculator and 500+ more calculators!

Verified by Mithila Muthamma PA

Coorg Institute of Technology (CIT), Coorg

Mithila Muthamma PA has verified this Calculator and 700+ more calculators!

< 13 Post-Tensioned Members Calculators

Variation of Eccentricity on Tendon A

Go Eccentricity Variation of Tendon A = Eccentricity at End for A+(4*Change in Eccentricity at A*Distance from Left End/Length of Beam in Prestress)*(1-(Distance from Left End/Length of Beam in Prestress))

Variation of Eccentricity of Tendon B

Go Eccentricity Variation of Tendon B = Eccentricity at End for B+(4*Change in Eccentricity B*Distance from Left End/Length of Beam in Prestress)*(1-(Distance from Left End/Length of Beam in Prestress))

Prestress Drop given Stress in concrete at Same Level due to Prestressing Force

Go Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Stress in Concrete Section/Modulus of Elasticity Concrete

Prestress Drop given Strain due to Bending and Compression in Two Parabolic Tendons

Go Prestress Drop = Modulus of Elasticity of Steel Reinforcement*(Strain due to Compression+Strain due to Bending)

Area of Concrete Section given Prestress Drop

Go Concrete Occupied Area = Modular Ratio for Elastic Shortening*Prestress Force/(Prestress Drop)

Average Stress for Parabolic Tendons

Go Average Stress = Stress at End+2/3*(Stress at Midspan-Stress at End)

Change in Eccentricity of Tendon A due to Parabolic Shape

Go Change in Eccentricity at A = Eccentricity at Midspan for A-Eccentricity at End for A

Stress in Concrete given Prestress Drop

Go Stress in Concrete Section = Prestress Drop/Modular Ratio for Elastic Shortening

Prestress Drop given Modular Ratio

Go Prestress Drop = Modular Ratio for Elastic Shortening*Stress in Concrete Section

Component of Strain at Level of First Tendon due to Bending

Go Strain due to Bending = Change in Length Dimension/Length of Beam in Prestress

Change in Eccentricity of Tendon B due to Parabolic Shape

Go Change in Eccentricity B = Eccentricity at Midspan B-Eccentricity at End for B

Prestress Drop

Go Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Change in Strain

Prestress Drop when Two parabolic Tendons are Incorporated

Go Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Concrete Strain

Prestress Drop Formula

Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Change in Strain
Δf_p = E_s*Δε_p

What is Loss due to Elastic Shortening?

When the prestress is transmitted to the concrete member, there is contraction due to prestress. This contraction causes a loss of stretch in the wire. When some of the stretch is lost, prestress gets reduced.
In pre tensioning process, the loss due to elastic shortening is considered but in post tensioning, No loss due to elastic deformation if all the wires are simultaneously tensioned. If the wires are successively tensioned, there will be loss of prestress due to elastic deformation of concrete.

How to Calculate Prestress Drop?

Prestress Drop calculator uses Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Change in Strain to calculate the Prestress Drop, The Prestress Drop is defined as the drop in prestress in the tendon due to change in strain of tendons. It is used to quantify the elastic shortening loss in prestress members. Prestress Drop is denoted by Δf_p symbol.

How to calculate Prestress Drop using this online calculator? To use this online calculator for Prestress Drop, enter Modulus of Elasticity of Steel Reinforcement (E_s) & Change in Strain (Δε_p) and hit the calculate button. Here is how the Prestress Drop calculation can be explained with given input values -> 0.1 = 200000000000*5E-05.

FAQ

What is Prestress Drop?

The Prestress Drop is defined as the drop in prestress in the tendon due to change in strain of tendons. It is used to quantify the elastic shortening loss in prestress members and is represented as Δf_p = E_s*Δε_p or Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Change in Strain. Modulus of Elasticity of Steel Reinforcement is a measure of its stiffness & Change in Strain is the train change in the tendons used in prestressed member.

How to calculate Prestress Drop?

The Prestress Drop is defined as the drop in prestress in the tendon due to change in strain of tendons. It is used to quantify the elastic shortening loss in prestress members is calculated using Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Change in Strain. To calculate Prestress Drop, you need Modulus of Elasticity of Steel Reinforcement (E_s) & Change in Strain (Δε_p). With our tool, you need to enter the respective value for Modulus of Elasticity of Steel Reinforcement & Change in Strain and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

How many ways are there to calculate Prestress Drop?

In this formula, Prestress Drop uses Modulus of Elasticity of Steel Reinforcement & Change in Strain. We can use 4 other way(s) to calculate the same, which is/are as follows -

Prestress Drop = Modular Ratio for Elastic Shortening*Stress in Concrete Section
Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Stress in Concrete Section/Modulus of Elasticity Concrete
Prestress Drop = Modulus of Elasticity of Steel Reinforcement*Concrete Strain
Prestress Drop = Modulus of Elasticity of Steel Reinforcement*(Strain due to Compression+Strain due to Bending)

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