Grade beams (tiebeams) are discussed in 1810.3.11 & 1810.3.12 in 2009 IBC. There was no mention of the 10% design value. 1810.2.2 discusses stability requirments for pilecaps.
I usually design the GB (stabilizing 1PC & 2PC) for the moment and shear due to piles being out of tolerance
I hate it when people eagerly try to respond to a thread to help a fellow engineer and he/she disappears and we keep guessing as to what his question really is.
I understand what you mean, but if you look at the record, casasf has started three threads to date and has made only one response. Does that tell you something?