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A pretensioned, prestressed concrete girder is to be built, with the same span and cross section as the girder in the example of Section 6.10. Pretensioning will be applied using twelve 0.5 -in. diameter stress-relieved Grade 270 strands, six of which are deflected upward at the one-quarter points of the span, to have zero eccentricity at the supports, the remainder being straight strands. The jacking force is $300,000 \mathrm{lb}$. Slip losses are fully compensated by overjacking, and friction at the tendon deflection points is negligible. Compute all losses, and express each as a percentage of the initial prestress $f_{p i}$ at midspan. Calculate the effectiveness ratio $R$. Compare the sum of losses due to elastic shortening, creep, shrinkage, and relaxation with the AASHTO recommended loss of Table 6.1. High early-strength concrete will be used, with $f_c^{\prime}=5,000$ psi. Steam-curing will be utilized, and prestress force will be transferred to the girder at age three days, when $f_c^{\prime}=3,500 \mathrm{psi}$.
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A pretensioned, prestressed concrete girder is to be built, with the same span and cross section as the girder in the example of Section 6.10. Pretensioning will be applied using twelve 0.5 -in. diameter stress-relieved Grade 270 strands, six of which are deflected upward at the one-quarter points of the span, to have zero eccentricity at the supports, the remainder being straight strands. The jacking force is $300,000 \mathrm{lb}$. Slip losses are fully compensated by overjacking, and friction at the tendon deflection points is negligible. Compute all losses, and express each as a percentage of the initial prestress $f_{p i}$ at midspan. Calculate the effectiveness ratio $R$. Compare the sum of losses due to elastic shortening, creep, shrinkage, and relaxation with the AASHTO recommended loss of Table 6.1. High early-strength concrete will be used, with $f_c^{\prime}=5,000$ psi. Steam-curing will be utilized, and prestress force will be transferred to the girder at age three days, when $f_c^{\prime}=3,500 \mathrm{psi}$.
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Design of Prestressed Concrete
Chapter 6
Chapter 1
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Sections
Problem 1 Problem 2 Problem 3 Problem 4
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