The effect of imperfections on the vertical buckling of railroad tracks

PDFTech ReportDOT-TSC-FRA-75-17FRA-OR&D-76-09RR519/R6321BucklingHigh temperatureStructural designDislocation (Geology)Thermal stressesHeatRailroad tracksUnited StatesJohn A. Volpe National Transportation Systems Center (U.S.)El-Aini, Yehia M.Princeton UniversityJohn A. Volpe National Transportation Systems Center (U.S.)United States. Federal Railroad Administration. Office of Research and DevelopmentVolpe National Transportation Systems Center, Technical Reference CenterThis report deals with an analytical prediction of the effect of geometric imperfections on the post-buckling characteristics of railroad tracks. The analysis is restricted to the case of vertical track buckling due to constrained thermal expansion in which the track is assumed to lift itself up over a finite span. The imperfections are categorized into two cases. Case (A) in which the region of imperfection is larger than the span of lift-off and Case (B) in which the imperfection region is smaller than the span of lift-off. It is shown that while a perfectly straight track does not exhibit bifurcation points from the undeformed state, the imperfect track does and that the bifurcation temperature in Case (A) is lower than in Case (B) for the same ratio of imperfection amplitudes reduces the bifurcation temperatures significantly. It is found that the bifurcation temperature as well as the safe temperature increase are higher for heavier tracks