Analysis of a typical railway turnout sleeper system using grillage beam analogy

A simplified grillage beam analogy was performed to investigate the behaviour of railway turnout sleeper system with a low value of elastic modulus on different support moduli. This study aimed at determining an optimum modulus of elasticity for an emerging technology for railway turnout application - fibre composites sleeper. The finite element simulation suggests that the changes in modulus of elasticity of sleeper, Esleeper and the sleeper support modulus, Us have a significant influence on the behaviour of turnout sleepers. The increase in Us from 10 to 40 MPa resulted in a 15% reduction in the bending moment while the increase in Esleeper from 1 GPa to 10 GPa has resulted in almost 75% increase in the bending moment. The shear forces in turnout sleepers is not sensitive to both the changes of the Esleeper and Us while the sleeper with low Esleeper tend to undergo greater settlement into the ballast. An Esleeper of 4 GPa was found optimal for an alternative fibre composite turnout sleeper provided that the Us is at least 20 MPa from the consideration of sleeper ballast pressure and maximum vertical deflection. It was established that the turnout sleeper has a maximum bending moment of 19 kN-m and a shear force of 158 kN under service conditions.

► The simplified grillage beam analogy is reasonable to model a complex railway turnout system.
► The behaviour of sleepers in a railway turnout is most critical between the switch and the frog.
► Modulus of elasticity and support stiffness has a significant influence on the behaviour of sleepers.
► The FEM analysis provided a basis for an optimum design of composite turnout sleeper alternative.