Structural Details and Bridge Performance

Examples observed in a group of about 4,000 steel, concrete and timber bridges illustrate maintenance problems caused by unsatisfactory details or by incorrect evaluation of the environment. Corrective measures and improved detailing and construction practices are suggested. Cracking in steel members occurred where high secondary stresses resulted from unequal loading of members connected in parallel, at stress raisers, and as a result of antiplane shear or of localized bending in a plane normal to the element plane at locations where deformation was concentrated by variations in stiffness of the load path. In most cases, fatigue was involved. Deterioration of all materials was caused by details that trap water, retard evaporation, or allow replacement of evaporated moisture. Extensive general deterioration of steel occurred in a chemically aggressive environment with only a light accumulation of rust and little pitting. Some details that caused maintenance problems obviously facilitated erection or were used to avoid conditions prohibited by design specifications.