initial prestressing force formula

The prestressing stress (or force) applied to . Beam length 3.5m. Initial Strain in Terms of Initial Prestressing Force Solution, Modulus of Elasticity of Steel Reinforcement. 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. Mithila Muthamma PA has verified this Calculator and 800+ more calculators! Prestressing is most often carried out using tensioned cables embedded in concrete. The initial force coefficient (FC. 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. Can't find what you're looking for? Initial strain is denoted by pi symbol. 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 . 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. 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. In this formula, Prestressing force Po uses Initial prestress force, Area of concrete & Transformed area of prestress section. 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. 3) where Kcir = 0.9 for pretensioned members Pi = initial prestress force (after anchorage seating loss) e = eccentricity of center of gravity of . Mithila Muthamma PA has verified this Calculator and 800+ more calculators! Initial Strain in Terms of Initial Prestressing Force calculator uses. Mithila Muthamma PA has verified this Calculator and 800+ more calculators! Initial prestress force is the force which is applied to the tendons by the jack. Prestressing force Po is denoted by Po symbol. If within tolerance, no worries. 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). 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. Elongation in., dividing the total initial force by this area results in a compressive stress over the total transformed area of 303.75/109 = Compression is positive. Initial strain is denoted by pi symbol. For practical cases, Eq. 10+ Pre-Tensioned Axial Members Calculators, Initial Strain in Terms of Initial Prestressing Force Formula. When I was first introduced to Eurocodes, I found this quite difficult to fathom, especially when comparing it to the simpler approach we adopted in BS5400 but I have now got used to it. 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. What are the disadvantages of prestressed concrete? Unlike structural steel, concrete is neither elastic nor time-independent. However, it is sufficiently accurate to base the elastic shortening loss on the initial prestress force Po, assumed constant along the member. 10+ Pre-Tensioned Axial Members Calculators, Modulus of Elasticity of Steel Reinforcement, Prestressing Force after Immediate Loss given the Initial Prestress Formula. Stages of Loading The analysis of prestressed members can be different for the different stages of loading. Ratio of transfer length to draw-in vs. initial prestress and power of bond stress-slip relationship. 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). 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, 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. The prestressing stress (or force) . 7-wire strands @ 0.153 in 2 per strand = 0.459 in2 f pu = 270 KSI (using an ordinary 7-wire strand) Initial prestress force, P s = 70%(f pu)(A ps) Service dead load, (NOT including beam weight) = 400 PLF Service beam weight = 188 PLF Service live load = 1500 PLF REQUIRED: How to calculate Initial Strain in Terms of Initial Prestressing Force using this online calculator? 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 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 How to Calculate Prestressing Force after Immediate Loss given the Initial Prestress? The disadvantages of prestressed concrete include: How to Calculate Initial Strain in Terms of Initial Prestressing Force? 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.) A high degree of workmanship and control is required. 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. Initial prestress force is the force which is applied to the tendons by the jack. Mithila Muthamma PA has verified this Calculator and 800+ more calculators! To change these values, you will need to use the general NDP form from the options menu. The disadvantages of prestressed concrete include: Initial strain here refers to the initial or immediate amount of strain in steel. 7.6.4.2.3 Form Finding Area of prestressing steel is the total cross sectional area of tendons. How to calculate Prestressing Force after Immediate Loss given the Initial Prestress? force in the strand by two inde-pendent methods. This page has been translated for your convenience with an automatic translation service. 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%) How to calculate Initial Strain in Terms of Initial Prestressing Force? The loss of the first prestressing force by the second prestressing force is 8.702% of the prestressing force, 4.286tf. How many ways are there to calculate Initial strain? Go to Solution. The equation given is as follows: % SR = [lift (R 0.55) X 100 (1) for R > 0.55 where % SR = % stress relaxation t = test time in hrs. Transformed area of prestress section is the area of the member when steel is substituted by an equivalent area of concrete. Ask the community or share your knowledge. 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. EQUATION SET DEVELOPMENT The use of these equations requires a preliminary estimate of the effective-ness ratio,R. 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: (8) provides values between 320 and 600 (see Fig. Force (kips) Initial Percent of Ultimate Load (%) Residual Load at 72 Hours (kips) Percent Stress Loss At 72 Hours (%) 34 82.3 26 23.5 28 67.8 27 3.6 This example indicates that strand, when kept in an overstressed condition (greater than 0.75 f' s), results in a significant reduction of prestressing force due to the change in creep . Most common method of prestressing used for factory production is a) Long line method b) Freyssinet system c) Magnel-Blaton system How to calculate Initial Strain in Terms of Initial Prestressing Force? In practice, the force in post-tensioned members at transfer is not constant owing to friction. 7 losses in prestress 1. It is not, however, necessary to as-sume all losses will have . c) to impart initial compressive stress in concrete d) all of the above Ans: c 139. 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. 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. What is initial prestressing force? Let me start with your last point in that there is no way to alter the initial prestress. 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) . 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 sum of the top and bottom prestressing forces is 2874.3975kN (2432.1825 + 442.215) - so where is the value of 2855kN coming from? Initial Strain in Terms of Initial Prestressing Force Solution, Modulus of Elasticity of Steel Reinforcement. The equation for stress in the prestressing steel at a distance x from the jacking end of the frame is: (Equation 1) . I believe the software does this until an appropriate convergence is reached and then reports a %age of the initial prestress that needs to be used (an information message pops up when the calcs are performed). What is Initial Strain in Terms of Initial Prestressing Force? In this formula, Initial strain uses Initial prestress force, Area of prestressing steel & Modulus of Elasticity of Steel Reinforcement. It is also called as the reduced value of prestressing force after elastic shortening, anchorage slip and loss due to friction. Steel is not necessarily in direct contact with concrete. The loss of stress in the tendon is therefore still given by Equation 4.1. = 0.20, K = 0.0002 (informational only). 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. 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. 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. How many ways are there to calculate Prestressing force Po? 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 disadvantages of prestressed concrete include: Prestress does not remain constant (reduces) with time. The force is then checked by measur-ing strand elongation and comparing this measured value with a theoretical (calculat- Area of concrete is defined as concrete area in beam or column excluding reinforcement. Initial prestressing force = 173.3 k: From Figures 2-5 and 2-6, the distance from the bottom of the beam to the centroid of Group 3 is 4.0 in. Chandana P Dev has created this Calculator and 600+ more calculators! a) At service, during operation. Assuming the force at transfer is 0.75*270 ksi the initial prestress force on the section is 0.75*270*1.5 = 303.75 kips. Modulus of Elasticity of Steel Reinforcement: Chandana P Dev has created this Calculator and 600+ more calculators! Thanks for an interesting question, and it is good to know that the printed output is being checked occasionally to verify the results. 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. The sum of the top and bottom prestressing forces is 2874.3975kN (2432.1825 + 442.215) - so where is the value of 2855kN coming from? 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]. Special alloy steels are more expensive than traditional steels used in reinforced concrete. 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. Initial Strain in Terms of Initial Prestressing Force calculator uses. This is defined' as the ratio of the effective prestressing force after all losses have occurred,P,, to the initial prestress force immediately after trans-fer,P,. Prestress Loss 2. Initial Strain in Terms of Initial Prestressing Force calculator uses. Share your knowledge, ask questions, and explore popular Structural Bridge Design topics. Thanks for your thorough response - much appreciated. Modulus of Elasticity of Steel Reinforcement is a measure of its stiffness. By my calculation this should be: I have included the material properties for the prestressing tendons as a screenshot. prestressing force immediately after the prestress has been applied to the concrete. 2. Initial prestress Fig. c) at time of prestressing A ps = 3 - " dia. 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: How to Calculate Initial Strain in Terms of Initial Prestressing Force? Modulus of Elasticity of Steel Reinforcement: Chandana P Dev has created this Calculator and 600+ more calculators! Prestressing Force after Immediate Loss given the Initial Prestress calculator uses. Initial prestress force is the force which is applied to the tendons by the jack. Modulus of Elasticity of Steel Reinforcement is a measure of its stiffness. This equation is used to predict the maximum force that can be induced onto a section. Introduction In prestressed concrete applications, most important variable is the prestress. 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). Even during prestressing of tendons, and transfer of prestress, there is a drop of prestress from the initially applied stress. 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). 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. However, the immediate losses are calculated as a function of the initial prestress, so this becomes an iterative procedure. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Thanks. 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. Ron (Structural) 9 Apr 17 03:04 Re-calibrate the jack and see if there's a difference. Load condition Erection time Formula Average Initial prestress 1 + [C.sub.a] 1.96 Prestress loss [[alpha].sub.a] (1 + 1.00 [chi] . If there is, apply the ratio of the difference to correct the values. Prestressing force Po is the prestressing force after immediate losses. Initial strain is denoted by pi symbol. 2) Intermediate : This includes the loads during transportation of the prestressed members. ~=_2_EP S 1-b fsi (8) This equation gives a relationship between the transfer length, the draw-in and the initial prestress. Area of prestressing steel is the total cross sectional area of tendons. 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 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. What is Initial Strain in Terms of Initial Prestressing Force? Initial prestress calculations With reference to the attached screenshots, I was hoping someone could explain how ASBD is calculating the total initial prestressing force (without reductions). Initial Strain in Terms of Initial Prestressing Force Solution, Modulus of Elasticity of Steel Reinforcement. a) During tensioning of steel b) At transfer of prestress to concrete. 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. b) At ultimate, during extreme events. 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. 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! 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 and is represented as. How many ways are there to calculate Initial strain? What are the disadvantages of prestressed concrete? A high degree of workmanship and control is required. With reference to the attached screenshots, I was hoping someone could explain how ASBD is calculating the total initial prestressing force (without reductions). Initial prestress force is the force which is applied to the tendons by the jack. Prestressing Force after Immediate Loss given the Initial Prestress calculator uses Prestressing force Po = Initial prestress force*Area of concrete/Transformed area of prestress section to calculate the Prestressing force Po, 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. 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. Back to Structural Bridge Design Category. The final strand force (measured as gauge pressure) is obtained from the shop drawings or plant engineering. Stages of Loading The analysis of prestressed members can be different for the different stages of loading. Welcome to Autodesks Structural Bridge Design Forums. 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. In this formula, Initial strain uses Initial prestress force, Area of prestressing steel & Modulus of Elasticity of Steel Reinforcement.

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