چكيده به لاتين
The use of continuous welded rails is necessary in high-speed railways. When this kind of rails cross through the bridges, longitudinal track-bridge interaction will be occurred. Because the bridge structure deforms under the impacts of thermal variation, bending of supporting structure and braking. Since bridges are important structures in railways, so track-bridge interaction is an important parameter in railway bridge design. In this study, finite element model of longitudinal track-bridge interaction is developed and verified in linear and nonlinear longitudinal stiffness cases. In order to solve a real problem, “Izadkhast railway bridge” with CWR track located in Isfahan-Shiraz railway have been selected and longitudinal track-bridge interaction with certain and uncertain approach have been studied about it. In certain approach rail stresses due to longitudinal track-bridge interaction under thermal variation, bending of the deck and braking obtained from nonlinear analysis and checked with permissible additional stresses. Effect of the stiffness being random along the track on rail stresses, has been studied. Parametric analysis of thermal variation, longitudinal distributed stiffness, location of vertical load and the amount of vertical load and braking load has been performed. Maximum rail stresses occurred when the third span of the bridge was loaded. In this case, maximum compression rail stress has been exceeded 22 percent from permissible stress. In uncertain approach, Reliability Analysis was done by MontCarlo simulation and FORM method. Also parametric analysis of coefficient of variation and the mean value of parameters was done. Reliability index for rail temperature variation 50 C and an increase in bridge temperature from 20 to 35 C has been 10 percent reduced.
Keywords: Longitudinal track-bridge interaction, nonlinear stiffness, random stiffness, reliability, Longitudinal rail stress, parametric analysis.
