Methods for developing indicative risk factors in the operation of bridge structures

A framework is developed for an industry-specific system of indicative risk factors pertaining to the repair and maintenance of bridge structures. Measures are defined for quality indicators and conformity assessment, including procedures for ranking and determining the cumulative risk associated with improperly selected forms of conformity assessment, as well as the risk of work outcomes that have undergone such assessment. A proposal is made to employ increments of relative deformation as criteria for the technical regulation of operational bridge structures in the analysis and calculation of failure risk. The author proposes the application of a novel ultimate (hazardous) state of the third type. The third group of limit states includes conditions under which a structure may experience unacceptable variations in the increments of relative deformation, leading to an unacceptable (hazardous) risk of harm — specifically, the destruction of bridge structure components. The calculations yield probabilistic-statistical indicators of the temporal and spatial changes in strength characteristics, as well as variations in the geometric dimensions and shape of structural elements, which result in unacceptable increments of relative deformation. To simplify risk calculation methods, a method for assessing the area of the distribution tail is proposed, based on approximating the distribution histogram with a normal distribution law, constructed from experimental (field, production) data. The application of a criterion for shortened distribution tails is suggested.