Bridge rating and reliability correlation:: Comprehensive study for different bridge types

Accumulation of research in the field of bridge evaluation based on structural reliability justifies the consideration of reliability index as the primary measure of safety for bridges. Furthermore, the lifetime bridge evaluation techniques are being mostly based on reliability methods. Currently, bridge safety is measured in terms of the rating factor, which reflects the live load capacity of the structure. In order to investigate the reliability index of an existing bridge and to consider its relation to the rating factor, an in-depth investigation of the interaction between these two safety measures for different limit states of different bridge types is desirable. This paper presents the results of a study in which the interaction between rating and reliability of a group of 14 bridges in an existing bridge network was investigated. This investigation is based on advanced methods to evaluate the reliability of each bridge in the network. Rating factors for different bridge groups are identified based on bridge type, and bridge groups are compared based on mean group rating factor. Bridge rating and reliability are quantified when each bridge starts its service life. The bridge rating factor and the reliability index are evaluated for various limit states belonging to different member types within the bridge network. A correlation study between bridge rating factor and reliability index of different bridge types in an existing network reveals interesting results.