Problem:

Why corrosion allowance is not taking in consideration for anchor bolts?

Corrosion Input in saddle bolting:

But still calculation done with non corroded bolt area, Why?

Answer:

Area of bolt is reduced by corrosion in Corroded Weight condition.

To perform the analysis with corroded weight condition, tick the Corroded Weight option available in Load Condition.

Then you will see the additional load combination in report, That will give the results with corroded condition.