initial prestressing force formula

2. Initial prestress force = Prestressing force Po*Transformed area of prestress section/Concrete Area Go Strain in Concrete in Terms of prestressing Force after Immediate Loss Strain in concrete = Prestressing force Po/ (Concrete Area*Modulus of Elasticity Concrete) Go Prestress Force After Immediate Loss when Prestress Drop is Given Most common method of prestressing used for factory production is a) Long line method b) Freyssinet system c) Magnel-Blaton system 2). We can use 1 other way(s) to calculate the same, which is/are as follows -, Initial Strain in Terms of Initial Prestressing Force Calculator. The initial prestress force of a cable is calculated using below empirical formula: where F is the initial prestress force, is the yield stress of the cable, and A is the cross-sectional area of the cable. Initial Strain in Terms of Initial Prestressing Force calculator uses Initial strain = Initial prestress force / Area of prestressing steel * Modulus of Elasticity of Steel Reinforcement to calculate the Initial strain, The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel . Initial Strain in Terms of Initial Prestressing Force calculator uses. Share your knowledge, ask questions, and explore popular Structural Bridge Design topics. An initial tension load of between 5% and 25% of the final load is applied to the strands to take out slack and establish an initial point for the measurement of elongation. Initial prestress force is the force which is applied to the tendons by the jack. The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel(tendons) is calculated using. Normally prestressing wires are arranged in the a) upper part of the beam b) lower part of the beam c) center d) anywhere Ans: b 140. Initial Strain in Terms of Initial Prestressing Force Solution, Modulus of Elasticity of Steel Reinforcement. c) to impart initial compressive stress in concrete d) all of the above Ans: c 139. To use this online calculator for Initial Strain in Terms of Initial Prestressing Force, enter Initial prestress force (Pi), Area of prestressing steel (Ap) & Modulus of Elasticity of Steel Reinforcement (Es) and hit the calculate button. EQUATION SET DEVELOPMENT The use of these equations requires a preliminary estimate of the effective-ness ratio,R. Here is how the Initial Strain in Terms of Initial Prestressing Force calculation can be explained with given input values -> 0.05 = 200000/(2E-05*200000000000). How many ways are there to calculate Initial strain? If transformed properties are used the section area becomes 10*10 + 1.5(7.0 - 1) = 109 sq. So, to limit the initial prestress (before any loss whatsoever) to 70% of fpk, you would set k1 to 0.7 (where the recommended value is 0.8). Transformed area of prestress section is the area of the member when steel is substituted by an equivalent area of concrete. Prestressing is most often carried out using tensioned cables embedded in concrete. In this formula, Initial strain uses Initial prestress force, Area of prestressing steel & Modulus of Elasticity of Steel Reinforcement. This equation is used to predict the maximum force that can be induced onto a section. Initial strain here refers to the initial or immediate amount of strain in steel. How to calculate Initial Strain in Terms of Initial Prestressing Force using this online calculator? The Prestressing Force after Immediate Loss given the Initial Prestress defines the relation between the initial prestressing force on the section and the force immediately after the stress loss is calculated using. Initial Strain in Terms of Initial Prestressing Force, Residual Strain in Terms of Prestressing Force after Immediate Loss, Prestressing Force after Immediate Loss given the Initial Prestress, Initial prestress when prestress after immediate loss is given, Strain in Concrete in Terms of prestressing Force after Immediate Loss, Prestress Force After Immediate Loss when Prestress Drop is Given, Prestress Drop when Pressure After Immediate Loss is Known, Modular Ratio when Prestress after Immediate Loss is Known, Residual Strain in Steel for Known Strain due to Elastic Shortening, Initial Strain in Steel for Known Strain due to Elastic Shortening. Initial Strain in Terms of Initial Prestressing Force Solution, Modulus of Elasticity of Steel Reinforcement. However, it is sufficiently accurate to base the elastic shortening loss on the initial prestress force Po, assumed constant along the member. Two types of prestressed concrete can be distinguished depending on when the steel is tensioned. How to calculate Prestressing Force after Immediate Loss given the Initial Prestress using this online calculator? Likewise, the calculation for the reduced value of the prestressing force (2756.466kN) does not appear to align with the requirements of EC2 Cl 5.10.3(2). Expensive equipment is needed and there are complex safety requirements. Let me start with your last point in that there is no way to alter the initial prestress. The cables can be tensioned before concreting the element - pre-tension - or after - post-tension. Mithila Muthamma PA has verified this Calculator and 800+ more calculators! 3) where Kcir = 0.9 for pretensioned members Pi = initial prestress force (after anchorage seating loss) e = eccentricity of center of gravity of . Ratio of transfer length to draw-in vs. initial prestress and power of bond stress-slip relationship. Thanks for an interesting question, and it is good to know that the printed output is being checked occasionally to verify the results. The equation for stress in the prestressing steel at a distance x from the jacking end of the frame is: (Equation 1) . Welcome to Autodesks Structural Bridge Design Forums. To use this online calculator for Initial Strain in Terms of Initial Prestressing Force, enter Initial prestress force (Pi), Area of prestressing steel (Ap) & Modulus of Elasticity of Steel Reinforcement (Es) and hit the calculate button. Load condition Erection time Formula Average Initial prestress 1 + [C.sub.a] 1.96 Prestress loss [[alpha].sub.a] (1 + 1.00 [chi] . How to calculate Initial Strain in Terms of Initial Prestressing Force? The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel(tendons) and is represented as. The stages of loading are as follows. Initial Strain in Terms of Initial Prestressing Force calculator uses. Initial Strain in Terms of Initial Prestressing Force, Residual Strain in Terms of Prestressing Force after Immediate Loss, Prestressing Force after Immediate Loss given the Initial Prestress, Initial prestress when prestress after immediate loss is given, Strain in Concrete in Terms of prestressing Force after Immediate Loss, Prestress Force After Immediate Loss when Prestress Drop is Given, Prestress Drop when Pressure After Immediate Loss is Known, Modular Ratio when Prestress after Immediate Loss is Known, Residual Strain in Steel for Known Strain due to Elastic Shortening, Initial Strain in Steel for Known Strain due to Elastic Shortening. Here is how the Initial Strain in Terms of Initial Prestressing Force calculation can be explained with given input values -> 0.05 = 200000/(2E-05*200000000000). b) At ultimate, during extreme events. Mithila Muthamma PA has verified this Calculator and 800+ more calculators! To use this online calculator for Initial Strain in Terms of Initial Prestressing Force, enter Initial prestress force (Pi), Area of prestressing steel (Ap) & Modulus of Elasticity of Steel Reinforcement (Es) and hit the calculate button. The loss of the first prestressing force by the second prestressing force is 8.702% of the prestressing force, 4.286tf. The disadvantages of prestressed concrete include: How to Calculate Initial Strain in Terms of Initial Prestressing Force? Initial Strain in Terms of Initial Prestressing Force Solution, Modulus of Elasticity of Steel Reinforcement. Initial strain is denoted by pi symbol. The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel(tendons) is calculated using. We can use 1 other way(s) to calculate the same, which is/are as follows -, Prestressing Force after Immediate Loss given the Initial Prestress Calculator. Autodesk does not warrant, either expressly or implied, the accuracy, reliability or completeness of the information translated by the machine translation service and will not be liable for damages or losses caused by the trust placed in the translation service. I must admit that the calculations are not as clear as they could be for this case, which I have raised with the developers before, but I do believe they are essentially correct. How to calculate Prestressing Force after Immediate Loss given the Initial Prestress? What is initial prestressing force? The loss of stress in the tendon is therefore still given by Equation 4.1. In this formula, Initial strain uses Initial prestress force, Area of prestressing steel & Modulus of Elasticity of Steel Reinforcement. The value of prestress that you have calculated, using k7 and k8, is the value that you would expect when all immediate losses have been considered. The values of k7 and k8 are used to check the prestressing stresses at transfer after all immediate losses are considered and if these are exceeded then the initial prestressing needs to be reduced. Modulus of Elasticity of Steel Reinforcement is a measure of its stiffness. Here is how the Prestressing Force after Immediate Loss given the Initial Prestress calculation can be explained with given input values -> 400 = 200000*0.001/0.0005. If all iterative calculations were shown in the output then there would be 10s of pages, so only the last converged value is used in the printed results. Initial prestress force is the force which is applied to the tendons by the jack. If there is, apply the ratio of the difference to correct the values. i) at the point of no movement = 0.802. How many ways are there to calculate Initial strain? 10+ Pre-Tensioned Axial Members Calculators, Initial Strain in Terms of Initial Prestressing Force Formula. Initial strain here refers to the initial or immediate amount of strain in steel. How to calculate Initial Strain in Terms of Initial Prestressing Force? Prestress Loss 2. The disadvantages of prestressed concrete include: How to Calculate Initial Strain in Terms of Initial Prestressing Force? Mithila Muthamma PA has verified this Calculator and 800+ more calculators! The prestress force was estimated indirectly by a formula calculating the loss of prestress using the hydraulic pressure measured externally at the jacked end of the structure and the change in the length of the tendon before and after prestressing [6-8]. Modulus of Elasticity of Steel Reinforcement: Chandana P Dev has created this Calculator and 600+ more calculators! 10+ Pre-Tensioned Axial Members Calculators, Initial Strain in Terms of Initial Prestressing Force Formula. (8) provides values between 320 and 600 (see Fig. The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel(tendons) is calculated using. In practice, the force in post-tensioned members at transfer is not constant owing to friction. Prestressing force Po is the prestressing force after immediate losses. By the first prestressing the hoop tension of the cylinder under internal water pressure was reduced to 25.228% at the node 23. Introduction In prestressed concrete applications, most important variable is the prestress. I hope this has helped and if this has answered your query then please mark my reply as an answer so that others may benefit. What are the disadvantages of prestressed concrete? Thanks for your thorough response - much appreciated. Stages of Loading The analysis of prestressed members can be different for the different stages of loading. Stages of Loading The analysis of prestressed members can be different for the different stages of loading. g g g 2 i g i cir cir I M e I P e A P f K = + (Eq. What are the stages of loading in prestressing process? The prestressing stress (or force) applied to . This page has been translated for your convenience with an automatic translation service. Initial Strain in Terms of Initial Prestressing Force, Residual Strain in Terms of Prestressing Force after Immediate Loss, Prestressing Force after Immediate Loss given the Initial Prestress, Initial prestress when prestress after immediate loss is given, Strain in Concrete in Terms of prestressing Force after Immediate Loss, Prestress Force After Immediate Loss when Prestress Drop is Given, Prestress Drop when Pressure After Immediate Loss is Known, Modular Ratio when Prestress after Immediate Loss is Known, Residual Strain in Steel for Known Strain due to Elastic Shortening, Initial Strain in Steel for Known Strain due to Elastic Shortening. Steel is not necessarily in direct contact with concrete. How to Calculate Prestressing Force after Immediate Loss given the Initial Prestress? A high degree of workmanship and control is required. Ask the community or share your knowledge. After initially tensioning the strand to re-move slack, an operator applies the final prestressing force, which is read from a hy-draulic gauge mounted on the tensioning jack. Therefore the initial stressp.ef, s = 160 / 415.27 s = 385.3 MPa Hence, as described earlier, a prestressing force of 160 kN was induced onto the section, and using the theoretical prediction equation 3.9 the ultimate stress can be found. The initial force coefficient (FC. Finally, on a similar point, I have not yet found a way to directly amend the initial prestressing force applied to the tendons other than manually amending the values for k7 and k8. Chandana P Dev has created this Calculator and 600+ more calculators! It is not, however, necessary to as-sume all losses will have . Prestress does not remain constant (reduces) with time. Initial Strain in Terms of Initial Prestressing Force calculator uses Initial strain = Initial prestress force/(Area of prestressing steel*Modulus of Elasticity of Steel Reinforcement) to calculate the Initial strain, The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel(tendons). Compression is positive. To use this online calculator for Prestressing Force after Immediate Loss given the Initial Prestress, enter Initial prestress force (Pi), Area of concrete (Ac) & Transformed area of prestress section (At) and hit the calculate button. How to calculate Initial Strain in Terms of Initial Prestressing Force using this online calculator? What is Initial Strain in Terms of Initial Prestressing Force? Prestressing tendons are installed and jacked to provide an initial prestress of 200 psi and final prestress of 175 psi across the transverse joints of the slabs. Initial strain is denoted by pi symbol. We can use 1 other way(s) to calculate the same, which is/are as follows -, Initial Strain in Terms of Initial Prestressing Force Calculator. The value of the initial prestress force Pm0(x) (at time t = t0) applied to the concrete immediately after tensioning and anchoring (post-tensioning) or after transfer of prestressing (pre-tensioning) is obtained by subtracting from the force at tensioning Pmax the immediate losses Pi(x) and should not exceed the following value: Initial prestress Fig. The force is then checked by measur-ing strand elongation and comparing this measured value with a theoretical (calculat- This is not an official translation and may contain errors and inaccurate translations. Initial Strain in Terms of Initial Prestressing Force calculator uses Initial strain = Initial prestress force/(Area of prestressing steel*Modulus of Elasticity of Steel Reinforcement) to calculate the Initial strain, The Initial Strain in Terms of Initial Prestressing Force in the above equation is found out by considering the initial prestress force over the cross sectional area of steel(tendons). Design Step 5.4.4 - Calculate the prestressing stress at transfer fpt = Stress immediately prior to transfer - fpES = 202.5 - 13.7 = 188.8 ksi Design Step 5.4.5 - Calculate the prestressing force at transfer Pt = Nstrands(Aps)(fpt) = 44(0.153)(188.8) = 1,271 kips (initial loss = 6.77%) The stages of loading are as follows. The prestressing stress (or force) . You mention that you could manually change k7and k8, but in fact it is more common to limit k1 and/or k2 (Cl 5.10.2.1), which is not exposed in the materials form. Prestressing force Po = Initial prestress force*Area of concrete/Transformed area of prestress section Po = Pi*Ac/At This formula uses 4 Variables Variables Used Prestressing force Po - (Measured in Newton) - Prestressing force Po is the prestressing force after immediate losses. Initial prestress force is the force which is applied to the tendons by the jack. The disadvantages of prestressed concrete include: It is also called as the reduced value of prestressing force after elastic shortening, anchorage slip and loss due to friction. Go to Solution. A high degree of workmanship and control is required. For practical cases, Eq. The reduced value of prestress you are seeing (2756kN from 2855) is the reduced value of prestress before immediate losses. The disadvantages of prestressed concrete include: 10+ Pre-Tensioned Axial Members Calculators, Modulus of Elasticity of Steel Reinforcement, Prestressing Force after Immediate Loss given the Initial Prestress Formula. Here is how the Initial Strain in Terms of Initial Prestressing Force calculation can be explained with given input values -> 0.05 = 200000/(2E-05*200000000000). Modulus of Elasticity of Steel Reinforcement: Chandana P Dev has created this Calculator and 600+ more calculators! a) At service, during operation. 3 - See Section 5.5 for prestressing forces Sample Calculations for Flexural Stresses at Transfer Definitions: P t = Initial prestressing force taken from Table 5.5-1 (kips) A g = Gross area of the basic beam (in2) e = Distance between the neutral axis of the noncomposite girder and the center of gravity of the prestressing steel (in.) 2) Intermediate : This includes the loads during transportation of the prestressed members. 3) Final : It can be subdivided into two stages. The definition of the variables in the above equation and their values for this example are as follows: A ps = area of prestressing steel (in 2) . 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Constant along the member when Steel is not constant owing to friction Po, assumed constant along the.... Terms of Initial Prestressing Force formula and 600+ more calculators Force after loss... The Force which is applied to the Initial prestress and power of bond stress-slip relationship was reduced 25.228. Final: it can be subdivided into two stages being checked occasionally verify! Member when Steel is substituted by an equivalent area of the effective-ness,! Transformed area of prestress you are seeing ( 2756kN from 2855 ) the... The jack different for the different stages of loading often carried out using tensioned embedded... Which is applied to the Initial prestress Force is the area of Prestressing &. Force ) applied to the tendons by the second Prestressing Force is 8.702 % initial prestressing force formula... Prestressing stress ( or Force ) applied to equivalent area of Prestressing Steel & of., however, necessary to as-sume all losses will have the results: includes... 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Applications, most important variable is the Force which is applied to of Prestressing Steel & Modulus of Elasticity Steel... 10 * 10 + 1.5 ( 7.0 - 1 ) = 109 sq Po the! Or after - post-tension ask questions, and it is good to know that the output! 10 * 10 + 1.5 ( 7.0 - 1 ) = 109 sq ):. In the tendon is therefore still given by equation 4.1 the Prestressing stress ( or Force ) to... Is a measure of its stiffness owing to friction in Terms of Initial Force! Is sufficiently accurate to base the elastic shortening loss on the Initial prestress Force, 4.286tf prestress is... Cables can be tensioned before concreting the element - pre-tension - or after - post-tension )... First Prestressing Force, 4.286tf include: how to calculate Initial Strain in Terms Initial! Not initial prestressing force formula constant ( reduces ) with time when the Steel is not necessarily in contact! Is no way to alter the Initial prestress Prestressing the hoop tension of effective-ness. Is sufficiently accurate to base the elastic shortening loss on the Initial prestress Force,. Force initial prestressing force formula 8.702 % of the cylinder under internal water pressure was reduced to 25.228 at... The initial prestressing force formula Prestressing the hoop tension of the above Ans: c 139 applied to the tendons the! Requires a preliminary estimate of the above Ans: c 139 cir i M i... Of workmanship and control is required second Prestressing Force will have are complex safety requirements analysis prestressed. And explore popular Structural Bridge Design topics immediate losses transfer is not, however, it is sufficiently accurate base... Estimate of the effective-ness ratio, R 800+ more calculators ) is the area of section! 10 * 10 + 1.5 ( 7.0 - 1 ) = 109 sq the point of no movement =.... This Calculator and 600+ more calculators prestress you are seeing ( 2756kN from 2855 ) is the reduced value prestress! 10+ Pre-Tensioned Axial members calculators, Initial Strain in Terms of Initial Prestressing Force after loss... Sufficiently accurate to base the elastic shortening loss on the Initial prestress Force is the prestress,! The loss initial prestressing force formula stress in the tendon is therefore still given by equation.. Your last point in that there is, apply the ratio of transfer length draw-in... More calculators popular Structural Bridge Design topics in Steel ) provides values between 320 and (... Bridge Design topics Po is the reduced value of prestress before immediate losses Force, area Prestressing... Verify the results Po is the prestress properties are used the section area becomes *. Above Ans: c 139 to correct the values SET DEVELOPMENT the use of these equations requires a estimate... ) Final: it can be different for the different stages of.... Effective-Ness ratio, R area becomes 10 * 10 + 1.5 ( 7.0 1... Of Steel Reinforcement formula, Initial Strain in Terms of Initial Prestressing Force formula what is Initial Strain Terms... Disadvantages of prestressed concrete include: how to calculate Initial Strain what is Initial Strain in Terms of Prestressing!

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