ABSTRACT
The principle aim of structural design is the assurance of satisfactory performance within the constraints of economy. A primary complication toward achieving this in practice is imperfect execution and the lack of complete information. The existence of uncertainties in structural engineering has long been recognized and quantitatively accounted for through the use of safety factors in design. Reliability analysis, using probability theory as a tool, provides a rational and consistent basis for determining the appropriate safety margins (Ang and Tang, 1984). Its success is exhibited by the numerous reliability-based provisions developed in recent code revisions to achieve a target reliability range in the design of structural elements (e.g., AISC, ACI, AASHTO). Over the last 20 years, research studies have been carried out to provide similar reliability provisions at the structural systems level, and perhaps they will have a more direct and substantial influence in design specifications over the next decade.
