With respect to the complex temperature load effects of CRTS Ⅱ slab ballastless track in China,the influence of temperature change rates on the thermodynamic performance of the CRTS Ⅱ slab track on a bridge was studied in this paper.Firstly,under a large-scale environment simulation testing box,temperature tests were conducted on five CRTSⅡ track slabs on a simply-supported box girder,using a 1∶4 geometric scale model,to compare and analyze the tem-perature and stress distribution of the scale model under three rates of ambient temperature change.Secondly,the heat conduction models of the scaled model with two constraint conditions of fixed and free boundary at both ends were estab-lished,and were validated by the experimental results.The 3D temperature field,stress field,and displacement of the scale models under two constraint conditions were analyzed,respectively.The results show that with the decrease of tem-perature change rate,the change amplitude of structural vertical displacement and internal temperature increase,while their values of each layer gradually decrease.The structural stress and the axial force of the track slab of the fixed con-straint condition continue to increase,especially when the temperature change rate decreases from 0.67 ℃/min to 0.44℃/min.In addition,the longitudinal stresses and vertical displacements of the track structure with non-constraint condition are smaller than those with fixed constraint condition,while their temperatures are larger than those with fixed constraint condition,which indicates that the fixed constraint condition could accelerate the heat transfer in the track structure.
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