Experimental investigation on shear steel bars in CRTS II slab ballastless track under low-cyclic reciprocating load

• Published in: Construction & building materials Vol. 255; p. 119425
• Main Authors: Feng, Yulin, Jiang, Lizhong, Zhou, Wangbao, Han, Jianping, Zhang, Yuntai, Nie, Leixin, Tan, Zhihua, Liu, Xiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.09.2020
• Subjects: Ballastless track; CA mortar layer; High-speed railway; Seismic performance; Shear steel bar; High-speed railway; Shear steel bar; CA mortar layer; Seismic performance; Ballastless track
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2020.119425

•No research on the seismic performance of the shear bar in track has been conducted.•Pseudo-static test with different shear bar quantity and diameter was carried out.•The influence of shear bar quantity and diameter on seismic performance was analyzed.•The deformation process and failure mechanism of the shear bar were revealed. To study the seismic behavior of shear steel bar in high-speed railway CRTS II slab ballastless track, low-cycle reciprocating load tests were carried out on 6 high-speed railway CRTS II slab ballastless track specimens with different shear steel bar quantity and diameter. The failure mode, hysteretic curve, skeleton curve, energy dissipation capacity, ductility, stiffness degradation law and strength degradation law of the shear steel bars were examined. The influence of the quantity and diameter of shear steel bars on seismic performance of the track was analyzed, and the deformation process and failure mechanism of shear steel bar under the action of low-cyclic reciprocating load was revealed. Results showed that the deformation process can be divided into three stages: a) the interface between track slab and CA mortar layer cracks, and shear deformation of the shear steel bar occurs; b) the shear steel bar repeatedly compresses the CA mortar layer and adjacent track slab concrete around it, and bending deformation of the shear steel bar occurs; c) the CA mortar layer and track slab concrete around shear steel bar are crushed, and the shear steel bar undergoes tensile deformation until it fractures. The failure mechanism of shear steel bar under the action of low-cyclic reciprocating load was not instantaneous clipping, but a kind of “fracture” between clipping and a pull cut. The larger the quantity and diameter of the shear steel bar, the stronger the energy dissipation capacity of the specimen and the better the seismic performance of the ballastless track. Increasing the quantity and diameter of the shear steel bar can effectively reduce strength and stiffness degradation of track under the action of low-cycle reciprocating load.