# prestressed concrete



## wimp (Sep 24, 2007)

ACI318 - 05 says max stresses in concrete are as follows...

for stresses in concrete immediately after prestress transfer

extreme fiber stress in compression = .6f'ci

extreme fiber stress in tension = 3 sqrt(f'ci)

extreme fiber stress in tension = 6 sqrt(f'ci)

for stresses in concrete after losses

.45 f'c for compression due to prestress plus sustained load

.60 f'c for compression due to prestress plus total load

two questions...

1) what does ACI 318-02 say for these values

2) what about the extreme fiber stress in tension for concrete after losses? I don;t see where this is covered in the code.

thanks


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## wimp (Sep 24, 2007)

Sorry everyone

not sure why this was posted three times

Wimp


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## Mcgill (Sep 25, 2007)

1) ACI 318-02 has the same values.

2) Section 18.3.3(ACI -02) has the limit for tensile stress at service level. That will classify your members as U,T or C and you will proceed accordingly.


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## wimp (Sep 25, 2007)

Mcgill said:


> 1) ACI 318-02 has the same values.2) Section 18.3.3(ACI -02) has the limit for tensile stress at service level. That will classify your members as U,T or C and you will proceed accordingly.


Not sure how I missed that! thanks for the reply


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