Evaluation of the damage and failure sequence of key components of track-bridge system for high-speed railway under seismic action is the basis for the design of a high-speed railway system and function recovery after earthquake. However, this evaluation has not been studied well. In this study, a simply supported beam with CRTS II track system and CRH2 high-speed train were taken as research objects. A train-bridge coupled finite element model was established, and experimental verification was carried out. Ten seismic waves exhibiting the highest matching degree with the site characteristics of bridge site were selected, and a nonlinear time-history analysis was carried out. The average peak ground acceleration (PGA) was obtained when each component suffered damage and failure for the first time, and the damage and failure sequences of components were arranged to analyze the seismic damage mode and failure mechanism of track-bridge system for high-speed railway. Finally, the corresponding damage and failure levels for track-bridge system were established. According to the research findings, under longitudinal earthquake, the damage and failure sequence of components is in the order of damage and failure of abutment sliding layer, damage of fixed abutment bearing, damage and failure of shear slot, failure of fixed abutment bearing, damage and failure of fixed pier bearing, and damage and failure of pier. Under transverse earthquake, the damage failure sequence of components is in the order of damage of abutment sliding layer, damage and failure of fixed pier bearing, damage of abutment sliding layer, damage of abutment fixed bearing, damage and failure of block, failure of fixed abutment bearing, and damage and failure of shear slot and pier. The fastener, mortar layer, and shear rebar remain in an intact state under transverse and longitudinal seismic motions. The dynamic effect of trains has no significant effect on the damage mode of track-bridge system for high-speed railway and yield order of key components.

Rail irregularity presents a major threat to the high-speed train (HST) safety on a high-speed rail (HSR) bridge. Lateral bridge deformation has a significant impact on geometric parameters of the rail. In this paper, the influence of lateral bridge deformation on the train operation on the HSR bridge is investigated. Variational calculus is employed to establish the analytical mapping between the lateral bridge and rail deformation. By superimposing the mapped rail deformation and initial random rail irregularity, the composed rail unevenness under lateral bridge deformation is obtained. Thereafter, by adopting the dynamical model of the train-track-bridge coupling system (TTBCS), the dynamic behaviour of the train moving across the HSR track-bridge system is analysed. Based on safety and comfortability control indicators of the HST operation, effects of different types of lateral bridge deformations with various amplitudes on the train’s operation performances are investigated. The results indicate that the bilateral girder’s mutual translation has the most significant impact on the train’s operation. When the HST is moving with the velocity of 350 km/h, lateral bridge deformation amplitude thresholds are suggested as 17.43 and 8.12 mm to ensure the safety and comfortability of the HST operation, respectively. The obtained results can provide beneficial pointers for HSR bridge design.

After an earthquake, a track-bridge system may suffer damage and residual deformation, posing a threat for trains passing over a bridge. However, since railway transportation is an important channel for disaster relief, the timely passage of trains is of great significance for the transportation of materials and personnel. In the past, subjective and experience-based judgments were made on whether a train can pass over an earthquake-damaged bridge, and no relevant numerical calculations were carried out. Therefore, a strategy for the evaluation of train performance when passing over existing bridges after earthquakes was proposed. The strategy considers the randomness of track irregularity, and evaluates the running safety performance (RSP) and running comfort performance (RCP) of trains passing over existing bridges from the perspective of probability. The probability law of a lateral residual bridge deformation influence on the RSP and RCP after an earthquake was revealed. Finally, the maximum train passing speed which ensures the RSP was recommended.

As an important lifeline of earthquake relief, railway transportation plays a crucial role in transportation tasks during earthquake relief and post-earthquake reconstruction activities. Determining the representative seismic-induced geometric irregularity of rail alignment is the key to analyzing the safety of train operation after an earthquake. In this study, by taking the high-speed train-CRTS II track-bridge system as the research object, a finite element model was established. From the PEER strong earthquake database, 40 ground motions showing the highest matching degree to the target response spectrum were selected as the ground motion input to establish a sample database of residual rail irregularity after an earthquake. Based on the sample database regarding irregularity, a type of representative seismic-induced geometric irregularity of rail alignment was constructed; the distribution patterns were summarized; and a simplified mathematical model was established, thus providing an irregularity excitation model for analyzing the safety of train operation after an earthquake. According to the research findings, the power spectrum density of the residual rail irregularity after an earthquake at each time-frequency point is subjected to a log-normal distribution. The mean and variance of the power spectrum density set for residual irregularity can be used to generate a definite seismic-induced geometric irregularity of rail alignment. The amplitude of seismic-induced irregularity significantly increases with the increase in PGA. With a smaller number of spans, the seismic-induced geometric irregularity of rail alignment can be considered to be composed of two approximately symmetric rail deformation sections. With a larger number of spans, it can be considered to be composed of a rail deformation section near the two ends of roadbed and the rail offset section in the middle.

In the dynamic analysis of railway lines, both lateral and vertical track irregularities should be considered. In addition, uncertainties in the bridge structure and train load will have different effects on the train-bridge coupled system (TBCS). This paper presents a three-dimensional model of the TBCS to study the influence of various sources of randomness on the response of the TBCS. The Karhunen–Loéve expansion is combined with the point estimate method (KLE-PEM) to calculate the statistical moment of the system response with high accuracy and efficiency. Furthermore, applicability of KLE-PEM method is discussed and the influence of different combinations of sources of randomness on the train and bridge responses under different speeds is analyzed according to the maximum range of probability values. Random track irregularities are found to have a much greater influence on the train response than uncertain parameters, whereas uncertain parameters have the greatest influence on the displacement of the bridge.