Prestress Drop given Initial Prestress Force Calculator

✖Initial Prestress Force is the force which is applied to the tendons by the jack.ⓘ Initial Prestress Force [P_i]			+10% -10%
✖Modular Ratio for Elastic Shortening is the ratio of the elastic modulus of a particular material in a cross-section to the elastic modulus of the “base” or the reference material.ⓘ Modular Ratio for Elastic Shortening [m_Elastic]			+10% -10%
✖Transformed Section Area of Prestress is the area of the member when steel is substituted by an equivalent area of concrete.ⓘ Transformed Section Area of Prestress [A_Pretension]			+10% -10%

✖Drop in Prestress is the drop in applied prestress force due to strain in tendons.ⓘ Prestress Drop given Initial Prestress Force [Δf_Drop]

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Formula

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Prestress Drop given Initial Prestress Force

Formula

`"Δf"_{"Drop"} = "P"_{"i"}*"m"_{"Elastic"}/"A"_{"Pretension"}`

Example

`"0.01044MPa"="435kN"*"0.6"/"0.025mm²"`

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Prestress Drop given Initial Prestress Force Solution

STEP 0: Pre-Calculation Summary

Formula Used

Drop in Prestress = Initial Prestress Force*Modular Ratio for Elastic Shortening/Transformed Section Area of Prestress
Δf_Drop = P_i*m_Elastic/A_Pretension
This formula uses 4 Variables

Variables Used

Drop in Prestress - (Measured in Pascal) - Drop in Prestress is the drop in applied prestress force due to strain in tendons.
Initial Prestress Force - (Measured in Kilonewton) - Initial Prestress Force is the force which is applied to the tendons by the jack.
Modular Ratio for Elastic Shortening - Modular Ratio for Elastic Shortening is the ratio of the elastic modulus of a particular material in a cross-section to the elastic modulus of the “base” or the reference material.
Transformed Section Area of Prestress - (Measured in Square Millimeter) - Transformed Section Area of Prestress is the area of the member when steel is substituted by an equivalent area of concrete.

STEP 1: Convert Input(s) to Base Unit

Initial Prestress Force: 435 Kilonewton --> 435 Kilonewton No Conversion Required
Modular Ratio for Elastic Shortening: 0.6 --> No Conversion Required
Transformed Section Area of Prestress: 0.025 Square Millimeter --> 0.025 Square Millimeter No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

Δf_Drop = P_i*m_Elastic/A_Pretension --> 435*0.6/0.025

Evaluating ... ...

Δf_Drop = 10440

STEP 3: Convert Result to Output's Unit

10440 Pascal -->0.01044 Megapascal (Check conversion here)

FINAL ANSWER

0.01044 Megapascal <-- Drop in Prestress

(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 » Pre-Tensioned Members » Prestress Drop given Initial Prestress Force

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Created by Chandana P Dev

NSS College of Engineering (NSSCE), Palakkad

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< 9 Pre-Tensioned Members Calculators

Prestressing Force after Immediate Loss given Initial Prestress

Go Prestressing Force after Loss = Initial Prestress Force*Pre-Tensioned Area of Concrete/Transformed Section Area of Prestress

Initial Prestress given Prestress after Immediate Loss

Go Initial Prestress Force = Prestressing Force after Loss*Transformed Section Area of Prestress/Pre-Tensioned Area of Concrete

Prestress Drop given Pressure after Immediate Loss

Go Drop in Prestress = (Prestressing Force after Loss/Pre-Tensioned Area of Concrete)*Modular Ratio for Elastic Shortening

Transformed Area of Prestress Member for Known Pressure Drop

Go Transformed Section Area of Prestress = Modular Ratio for Elastic Shortening*Initial Prestress Force/Drop in Prestress

Prestress Drop given Initial Prestress Force

Go Drop in Prestress = Initial Prestress Force*Modular Ratio for Elastic Shortening/Transformed Section Area of Prestress

Modular Ratio given Prestress after Immediate Loss

Go Modular Ratio for Elastic Shortening = Drop in Prestress*Pre-Tensioned Area of Concrete/Prestressing Force after Loss

Residual Strain in Steel for Known Strain due to Elastic Shortening

Go Residual Strain = Initial Strain-Concrete Strain

Initial Strain in Steel for Known Strain due to Elastic Shortening

Go Initial Strain = Concrete Strain+Residual Strain

Strain in Concrete due to Elastic Shortening

Go Concrete Strain = Initial Strain-Residual Strain

Prestress Drop given Initial Prestress Force Formula

Drop in Prestress = Initial Prestress Force*Modular Ratio for Elastic Shortening/Transformed Section Area of Prestress
Δf_Drop = P_i*m_Elastic/A_Pretension

What are the methods to Predict Prestress Loss?

They are listed according to their descending order of perceived accuracy:
(a) Time-Step methods;
(b) Refined methods;
(c) Lump-Sum methods.

How to Calculate Prestress Drop given Initial Prestress Force?

Prestress Drop given Initial Prestress Force calculator uses Drop in Prestress = Initial Prestress Force*Modular Ratio for Elastic Shortening/Transformed Section Area of Prestress to calculate the Drop in Prestress, The Prestress Drop given Initial Prestress Force is defined as decrease in prestress on tendons due to change in strain. Drop in Prestress is denoted by Δf_Drop symbol.

How to calculate Prestress Drop given Initial Prestress Force using this online calculator? To use this online calculator for Prestress Drop given Initial Prestress Force, enter Initial Prestress Force (P_i), Modular Ratio for Elastic Shortening (m_Elastic) & Transformed Section Area of Prestress (A_Pretension) and hit the calculate button. Here is how the Prestress Drop given Initial Prestress Force calculation can be explained with given input values -> 4.8E-9 = 435000*0.6/2.5E-08.

FAQ

What is Prestress Drop given Initial Prestress Force?

The Prestress Drop given Initial Prestress Force is defined as decrease in prestress on tendons due to change in strain and is represented as Δf_Drop = P_i*m_Elastic/A_Pretension or Drop in Prestress = Initial Prestress Force*Modular Ratio for Elastic Shortening/Transformed Section Area of Prestress. Initial Prestress Force is the force which is applied to the tendons by the jack, Modular Ratio for Elastic Shortening is the ratio of the elastic modulus of a particular material in a cross-section to the elastic modulus of the “base” or the reference material & Transformed Section Area of Prestress is the area of the member when steel is substituted by an equivalent area of concrete.

How to calculate Prestress Drop given Initial Prestress Force?

The Prestress Drop given Initial Prestress Force is defined as decrease in prestress on tendons due to change in strain is calculated using Drop in Prestress = Initial Prestress Force*Modular Ratio for Elastic Shortening/Transformed Section Area of Prestress. To calculate Prestress Drop given Initial Prestress Force, you need Initial Prestress Force (P_i), Modular Ratio for Elastic Shortening (m_Elastic) & Transformed Section Area of Prestress (A_Pretension). With our tool, you need to enter the respective value for Initial Prestress Force, Modular Ratio for Elastic Shortening & Transformed Section Area of Prestress 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 Drop in Prestress?

In this formula, Drop in Prestress uses Initial Prestress Force, Modular Ratio for Elastic Shortening & Transformed Section Area of Prestress. We can use 1 other way(s) to calculate the same, which is/are as follows -

Drop in Prestress = (Prestressing Force after Loss/Pre-Tensioned Area of Concrete)*Modular Ratio for Elastic Shortening

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