Abstract
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. This paper discusses the criteria for calibrating the ISO-LRFD based on the API studies. Other topics include actual versus notional reliabilities, regional load factors, member versus system reliability, and selecting a design return period. The paper also describes safety indices for the combined loading interaction formulas. [S0892-7219(00)01301-7]