Design of piles for integral abutment bridges.

754849934PDFTech ReportPiles (Supports)AbutmentsBridge abutmentsBridge substructuresIowaIowa. Dept. of TransportationGreimann, L. F.Yang, P. S.Edmunds, S. K.Wolde-Tinsae, A. M.Iowa State UniversityIowa. Dept. of TransportationIowa. Highway Research BoardNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresUS Transportation CollectionMore and more, integral abutment bridges are being used in placeof the more traditional bridge designs with expansion releases. Inthis study, states which use integral abutment bridges were surveyedto determine their current practice in the design of these structures.To study piles in integral abutment bridges, a finite element programfor the soil-pile system was developed (1) with materially andgeometrically nonlinear, two and three-dimensional beam elements and(2) with a nonlinear, Winkler soil model with vertical, horizontal, andpile tip springs. The model was verified by comparison to severalanalytical and experimental examples.A simplified design model for analyzing piles in integral abutmentbridges is also presented. This model grew from previous analytic2lmodels and observations of pile behavior. The design model correctlydescribes the essential behavioral characteristics of the pile andconservatively predicts the vertical load-carrying capacity.Analytical examples are to illustrate the effects oflateral displacements on the ultimate load capacity of a pile. Theseexamples include friction and end-bearing piles; steel, concrete, andtimber piles; and bending about the weak, strong, and 4S0 axes forH piles. The effects of cyclic loading are shown for skewed and nonskewedbridges. The results show that the capacity of friction pilesis not significantly affected by lateral displacements, but thecapacity of end-bearing piles is reduced. Further results show thatthe longitudinal expansion of the bridge can introduce a vertical preloadon the pile