# 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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## pelotoner (Oct 23, 2007)

wimp:

1. ACI318-02 says the same thing.

2. The limit for tension is 6*sqrt(f'c). Bonded rebar is required when the tension exceeds 2*sqrt(f'c).

See 18.9.3.1.


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