Donaire-Ávila Jesús, Montañés-López Antonio, Suárez Fernando
Department of Mechanical and Mining Engineering, University of Jaén, 23700 Linares, Spain.
Campus Científico-Tecnológico de Linares, Cinturón Sur, 23700 Linares, Spain.
Materials (Basel). 2019 Aug 26;12(17):2731. doi: 10.3390/ma12172731.
Prestressed monoblock railway sleepers are concrete elements with almost no reinforcement apart from the prestressing wires, which makes them very sensitive to any stress variation that can induce tensile stresses. In recent years, severe longitudinal cracking has been observed in a number of sleepers in hot regions of Spain, even before these elements were put in service. This work studies the problem while considering the thermal variation as the main factor affecting this cracking phenomenon. A non-linear static load-step analysis is applied on a non-linear finite element model to reproduce the problem and, after its experimental validation, the influence of three design parameters of the sleepers are studied: the nature of concrete aggregates, the dowel thickness, and the dowel material. The results show that all these three parameters may have significant influence on the problem, with the dowel material being the most important parameter. When the dowels are made of a material with a high elastic modulus and a high thermal expansion coefficient, the crack opening induced by a realistic thermal variation can reach significant values and result in longitudinal crack propagation. The changes of humidity are not considered in this study because they are beyond the scope of this work.
预应力整体式铁路轨枕是一种混凝土构件，除了预应力钢丝外几乎没有配筋，这使得它们对任何可能引起拉应力的应力变化都非常敏感。近年来，在西班牙炎热地区的一些轨枕中，甚至在这些构件投入使用之前，就观察到了严重的纵向开裂。这项工作在将热变化视为影响这种开裂现象的主要因素的情况下研究该问题。在非线性有限元模型上应用非线性静态加载步分析来重现该问题，并在其实验验证之后，研究轨枕的三个设计参数的影响：混凝土骨料的性质、销钉厚度和销钉材料。结果表明，所有这三个参数可能对该问题有重大影响，其中销钉材料是最重要的参数。当销钉由具有高弹性模量和高热膨胀系数的材料制成时，实际热变化引起的裂缝开口可能达到显著值并导致纵向裂缝扩展。本研究未考虑湿度变化，因为它们超出了本工作的范围。
