allowable stress increase for existing structures

[PSF]

I remember using an allowable stress increase for existing steel, but I cannot find where it came from. It was in the order of 3% to 5%. AS long as your new loads did not increase the stress by that percentage it was OK to add the load. Does anyone know what I am referring to? Thanks.

 

[Taro]

Try 2003 IBC Section 3403.2.

 

[jike]

Also 2000 IBC Section 3402.2