IBC Chapter 34: 3404

[DHKpeWI]

Please read the following from the 2009 IBC, Chapter 34, Section 3404. It appears to mean that if the P/Pall for a member in an altered structure cannot be more than 10% greater than P/Pall for the unaltered structure. But this doesn't make any sense to me.

Let say that for a given member in an existing building P/Pall = 0.8. If that same member has a P/Pall of greater than 0.88, then the member has to be reinforced even though the interaction is less than 1.0.

Am I reading this wrong?

 

[DHKpeWI]

Forgot to include section from IBC.

 

[SteelPE]

Why are you looking at the exception. If your member complies with chapter 16 (in your example it does because P/Pall<1.0) then no reinforcing is required. If your member does not comply with chapter 16 then you have a little room (with the exception) before you need reinforcing.

At least this is how I read the section.

 

[DST148]

@DHKpeWI: See if discussion in thread507-316624 would help.