A study supported by the American Petroleum Institute established that load
and resistance factor design offers improvement in design and is supported
by credible data, can yield improved designs of greater reliability and/or
economy and is in reasonable accordance with current design practices. Thi
s paper discusses the criteria for calibrating the ISO-LRFD based an the AP
I studies. Other topics include actual versus notional reliabilities, regio
nal load factors, member versus system reliability, and selecting a design
return period. The paper also describes safety indices for the combined loa
ding interaction formulas. [S0892-7219(00)01301-7].