ABSTRACT
The objective of this study is to evaluate the system reliability of girder bridges. Particular attention is given to the interaction of secondary elements that may significantly affect reliability; namely barriers, sidewalks, and diaphragms. Simple span, two lane structures are considered, with composite steel girders supporting a reinforced concrete deck. For structural analysis, a finite element procedure is developed that is later simplified to a grillage model for reliability analysis. Random variables considered are composite girder, barrier, and sidewalk flexural strengths (each in turn composed of many random variables), load magnitude (dead load and truck traffic live load), and live load position. System resistance is defined as a global criterion, ultimate moment capacity, rather than a sequence of element failures. Resistance parameters are estimated with a quadrature integration of the joint probability density function. System reliability is calculated for a variety of bridges using a first order method once system resistance and load parameters are developed. It was found that the interaction of typical secondary element combinations has a varying effect on system reliability, depending on element stiffness, bridge span, and girder spacing.
