Structural Reliability

Abstract

In this paper, we summarize our viewpoints on structural reliability including the effects of structural control and symptom-based reliability for readers who may not be structural engineers. Structural reliability, which refers to the application of probabilistic methods in studying structural safety, depends very much on temporal factors. Traditionally, structural reliability has been defined as the probability of the useful life of a given structure exceeding a certain time-period, t. It is a good measure of the level of safety for structures that are made of various materials. However, the authors are convinced that it is more meaningful to base reliability of existing structures on symptoms that can be related to structural damage. We will describe the symptom-based reliability in more details later. Control systems can be considered as additional redundancies that improve the structural reliability. Recently, many active control systems (both passive and active) have been developed and used in bridges and buildings, especially in Japan. Fuzzy control has also been studied. In the seventies, efforts were made to apply structural reliability in design codes resulting in LRFD (Load and Resistance Factor Design) specifications. Nevertheless, almost every expert is an analyst. We believe that no further progress can be made unless many more experiments will be conducted. Structural reliability will be applied to performance-based design, and structural performance should be assessed for structural sustainability and adaptability to the temporal changes of natural and social environments. Our viewpoints along these lines have been expressed herein.