Improving shear deficiency of prestressed concrete sleepers by crack resisting stirrups

Prestressed concrete (PC) sleepers are used in modern railway systems worldwide. Although the PC sleepers are durable under harsh environmental conditions, frequent cracks can be found hindering the railway's capacities. This article investigates an improvement of placing steel stirrups in shear deficient PC sleepers commonly used in railways of Thailand. PC sleepers with a cross-section of 258 x 205 mm(2) varied with five different stirrup's ratios were tested under a three-pointed bending load to observe the improvement of shear resistance. From the experimental results, the peak load of PC sleepers with stirrups can be enhanced from 14.1% to 21.2%, whilst the failure deformation can also be enhanced from 87.5% to 176.6%, compared with PC sleeper without any stirrup. With increasing stirrup's ratio, failure modes of PC sleepers were shifted from brittle shear to ductile flexural failures. Moreover, the PC sleepers with deformed-bar stirrups exhibited better bond interfaces than that with rounded-bar. Then, the proper stirrup's ratio and type of steel stirrups are recommended to enhance the shear resistance of the PC sleeper. In addition, a finite element analysis results based on advanced constitutive models and the fixed-cracking approach showed good agreement with the results from experiment.