Fracture Mechanics Analysis of Pre-stressed Concrete Sleepers by Investigating Effects of Notch Size

Document Type : Research Paper

Authors

Bu Ali Sina university

Abstract

High-speed heavy-haul pre-stressed concrete sleepers are used in railway lines with bearing capacity up to 30 tons and with an allowable speed up to 200 km/hr due to their high performance capability. In this study, it is tried to analyze the fractural behavior of pre-stressed concrete sleepers based on fracture mechanics of concrete. To determine the parameters, a positive three-point bending load is applied to the rail seat of a sleeper with 6 different initial crack (notch) lengths, starting from 0 to 40 mm, with an increasing increment of 10 mm, and also 45 mm. The modelling of high-speed heavy-haul sleeper is done by ABAQUS finite element software. In this paper, some paramount parameters of fracture mechanics for concrete are considered for analyzing and designing e.g. the initial and final stress intensity, load-displacement diagram, final load and the sleeper energy. The results indicate that the fracture parameters of pre-stressed concrete sleeper are different from plain concrete. Unlike plain concrete which the stress intensity factor does not depend on the initial length of the notch, in pre-stressed concrete by increasing the crack length, both of the initial and final stress intensity factors are increased. Also, the results of the time-displacement diagram show that by increasing the crack length, the final load and energy of the pre-stressed concrete sleeper decreases almost linearly. Results represent that by increasing the notch length up to 25%, the area under load-displacement curve decreases up to 37%; while the final load decreases up to 22%.

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