Optimization of serviceability load combinations for structural steel beam design

Abstract

In Australia, typical design load combinations for serviceability are Ψ s Q and G + Ψ s Q ( D and D + L in the US) where G and Q are design dead and live loads, respectively, and Ψ s is a short-term live load factor. Code calibration is conducted herein for Australian and US serviceability load combinations, for structural steel beams in flexure. The effects that office, retail, domestic and car parking loads and tributary areas have on serviceability reliability is described. It was found that serviceability reliabilities for different floor uses vary considerably for Australian and US serviceability load combinations; whereas the differences between serviceability reliabilities for one year and duration of a single tenancy reference periods were not great. Short-term live load factors for most floor uses were adjusted (sometimes significantly) to ensure that serviceability reliabilities exceed the minimum target level of 1.65. Consequently, the present paper provides suggested values for short-term live load factors that may be used in Australian and possibly in US codes.