ACI 350-06 : Durability Factor quick question,

[engrnmc]

Just a quick question, assuming that Durability factor (Sd) is already attained, Sd will be multiplied to the factored moment right and not the service moment?

second, after multiplying the Durability factor to the factored moment, now you can design with the required reinforcement irregardless from the spacing and rebar you had considered in attaining the durability factor (Sd)?

hope some one can enlighten me,

 

[JAE]

Take a look at this post:
thread507-273684

It also references out to some others - hope this helps.

Check out Eng-Tips Forum's Policies here:
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[engrnmc]

ThaBks. But i think the second i was trying to ask was not tackled in the thread.

But thanks alot

 

[jayrod12]

The answer to your section question would be once you've chosen a durability factor from the original design, then you've increased the factored moment and therefore are increasing the reinforcing, you're covered. You're already designing to a doubly factored moment.

 

[engrnmc]

Ok thanks for your answer.

I thougth you will be bounded by the spacing and the rebars from what you had used in getting your durability factor. Since the main idea of the durability factor is to add additional factor to account for cRacking.

My experience from my rough calculation is that the steel required based on the service load, as i was trying to get the Sd ,is morethan what im getting. Since im limitlimited to take fs to 36ksi only.

 

[GBStruct]

Yes, the durability factor is applied to a factored moment.

The durability factor is directly related to reinforcing bar size and spacing, so you will have to recalculate the Sd for the chosen reinforcing arrangement to verify that your factor has not increased to the point where your design moment exceeds your capacity. Generally smaller bars at a smaller spacing result in lower Sd factors (on a As/square foot basis). A spreadsheet for various bar sizes and spacings is a great tool/timesaver. I suggest creating one for normal environment and one for severe environment while you are at it.