# A New Top-Mounted Shear-Hinge Structure Based on Modal Theory and Rubber-Pad Damping Theory
## 1 Introduction  
Steel-spring floating-slab tracks (SSFST) are one of the most successful types of tracks used in urban rail transportation worldwide, and their vibration-damping effect is globally recognized [1, 2]. This is especially true in China, where urban rail transportation has developed rapidly in recent years, including subways, which are developing at a steady rate, and the new urban railroad, which is undergoing rapid development [3]. SSFSTs are used in large quantities and are composed of a rail, a floating slab, a steel-spring isolator, fasteners, and a shear hinge. SSFSTs are strong and discrete and therefore require theinstallation of shear hinges to enhance the integrity of the bed, where the shear hinges, which connect the floating slabs, restrain the vertical and lateral differential movements of the slab ends [4]. Damage to different elements of SSFSts under long-term train loading can directly affect the safety and stability of the SSFST system and vehicle operation [5; 6; 7; 8]. As a structure that connects the floating slabs, the TMSH undergoes damage, such as loose and broken bolts and broken shear rods, during its service period. This damage accelerates fatigue damage to the fasteners and steel spring at the joint of the floating slab, which indirectly affects the service performance of the floating slabs and the railway. Thus, it is important to address the problem of damage to TMSHs in SSFSts [9; 10; 11]. Of the few studies on shear hinges, most focus on the effects of the shear-hinge structure and structural parameters on the performance of floating-slab tracks. [PERSON] et al. [12] set up a dowel joint, the earliest shear hinge, in an FST with an efficient joint model based on shear springs. They conducted vibration tests on the floating-slab track under four different working conditions regarding the installed positioning bar to study its effects on the load-transfer rate of the FST. The floating-slab track with the shear hinges installed was used to study the effect on the FST load-transfer rate and prove that the FST had good load-transfer capability after the installation of shear hinges. In addition, the accuracy of the finite-element model (FEM) model was verified through tests. [PERSON] et al. [13] also compared a shear hinge to a shear spring to study the effect of stiffness variation on the dynamic performance of a floating slab. [PERSON] et al. [14; 15] utilized a more complex shear spring to simulate a shear hinge to study the effect of a floating slab's length on its vibration response and the surrounding environment's vibration. [PERSON] et al. [16] used a shear spring-dashpot model and a bending spring-dashpot model to simulate a shear hinge and compared the dynamic responses of the FST using two models. The authors demonstrated that both models could reduce the dynamic response of the floating slab. The above studies did not address the causes of damage to shear hinges or the measures that can be taken to address the damage. Moreover, they all used the shear spring or the spring-dashpot model to simulate shear hinges, which can only assess a shear hinge's performance from a single direction, and lack accuracy. Since no research has been published on damage to top-mounted shear hinges, this paper will draw on the practices of other authors to analyze the causes of damage and optimize the design of their structure. [PERSON] et al. [17] obtained the modal characteristics of fasteners under different preload assembly conditions through field tests, established a refined model of the fasteners, analyzed the dynamic characteristics of the elastic strips in the fasteners from both static and dynamic perspectives, revealed their fatigue damage mechanisms, specified the distribution characteristics of vulnerable points, and provided suitable values for the preloading of fasteners. [PERSON] et al. [18] established a fastener refinement model and performed static and dynamic analyses of the fastener sling under assembly conditions based on nonlinear contact theory.