evaluating the structural behavior of turnout sleepers in the case of raising speed

in this research, the structural behavior of timber and concrete sleepers in a standard railway turnout is evaluated, in the case of raising speed. in approaching this evaluation, current practices in the structural analysis of sleepers are surveyed and then, the sensitivity analysis with abaqus software is made based on selected criteria (bending and shear stresses as well as contact pressure). considering various sleepers with different dimensions in a turnout, two specific ones are selected as the representatives of moving (switch) and fixed (frog) parts. the results show that the maximum bending stress of timber sleeper compared to the concrete is reduced to about 55%, due to more flexibility. however, better behavior is resulted in concrete sleeper because of higher strength of materials. meanwhile, the contact pressure between the timber sleeper and ballast layer is 80% higher which means that, the concrete sleeper provide better stress distribution for ballast materials. the effects of speed increase from 150 to 300 km/hr also lead to an increase of about 30% in the stresses outputs.