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

Earthq Engng Struct Dyn

et al. 2023

Self Cite

There has been no consensus on post‐earthquake operating plan for high‐speed railway trains. In this paper, two three‐dimensional coupling model of track‐bridge system without and with trains for high‐speed railways were developed, and their performance were verified based on shaking table tests. The equivalent method of design seismic track irregularity for random structures was discussed, and the amplitude response spectra of design seismic track irregularity for all levels of seismic intensity were proposed. In addition, the rationality of design seismic track irregularity was evaluated based on engineering case analysis, providing a theoretical foundation of formulating post‐earthquake contingency plans for high‐speed railways. The results show that when span number increases, the design seismic track irregularity amplitude increases and then tends to be stable; when the span number reaches 9, the train dynamic response gradually becomes stable; the random structures with arbitrary span numbers are equivalent to a specific 9‐span structure when constructing design seismic track irregularity. When the seismic intensity is low, there is no significant difference in shape and amplitude between the measured pre‐earthquake and post‐earthquake track alignment irregularities, and the train can normally run with no significant deceleration required. The train dynamic response under the design post‐earthquake track irregularity is greater than that under the measured post‐earthquake track irregularity, indicating that the design seismic track irregularity has a reasonable safety margin and a good feasibility in engineering practice.

Section: Coupling Model Without Trainsmentioning

confidence: 99%

Design seismic track irregularity for high‐speed railways

Earthq Engng Struct Dyn

et al. 2023

Self Cite

“…The generalized cross section needs to define the constitutive relations of moment-curvature, which were depicted in Figure 3. 22 Bearings, 23 sliding bed, 3 mortar bed, 24 fasteners, 25 shear grooves, 24 shear reinforcements, 26 F I G U R E 2 Illustration of the track subsystem (dimensions in mm) transverse blocks, 24 and terminal spines 3 were modeled as nonlinear components (COMBIN39). See Figure 3 for the detailed constitutive relations.…”

Section: Hsr System Without Trainmentioning

confidence: 99%

Response spectra of fitted post‐seismic residual track irregularity for high‐speed railway

Earthq Engng Struct Dyn

2022

Self Cite

Chinese high‐speed railway (HSR) network construction has expanded into earthquake‐prone areas. In this context, analyses of post‐seismic residual track irregularity and post‐seismic train speed threshold are vital. With a HSR bridge with track system taken as the study object, time‐domain signal for target post‐seismic residual track irregularity was constructed based on the Gaussian pulse translation theory. The response spectra of fitted post‐seismic residual track irregularity applicable to stochastic structures were established, thus providing irregularity input for ascertaining post‐seismic speed threshold. The results show that residual alignment irregularity has a large amplitude under transverse seismic actions; by contrast, cross‐level, gauge, and vertical irregularities showed small amplitudes. The evolution power spectral density (EPSD) of the stochastic post‐seismic residual track irregularities obeys a definite distribution in any frequency‐space coordinate. A uniquely deterministic target post‐seismic residual track irregularity can be constructed based on the stochastic irregularity set, and its safety guarantee rate can be precisely controlled by varying the significance level. Taking the first‐order transverse natural vibration period as the x‐axis and the amplitude of fitted post‐seismic residual track irregularity as the y‐axis, the response spectra of fitted post‐seismic residual track irregularity can be created. The irregularity response spectra are applicable to stochastic structures.

“…Considerable researches have been conducted to investigate the track constraint effects on the bridge. These studies mainly focus on bridge-track interaction [11,12] or train-track interaction [13][14][15] . Maragakis [16] investigated the effect of tracks on the dynamic performance of Strawberry Park ballasted bridge.…”

Section: Introductionmentioning

confidence: 99%

Control of Difference of Seismic Response Across Different Spans of High-Speed Railway Multi-Spans Simply Supported Bridge

Zhang

et al. 2021

Preprint

Self Cite

In this paper, the Difference of Seismic Response across Different Spans (DSR) in the longitudinal distribution of High-Speed Railway Multi-spans Simply Supported Bridge (HSRSB) under longitudinal earthquake excitation is investigated, and an evaluation method which can intuitively reflect the difference of seismic response is proposed. A feasible way to strengthen the connection stiffness between adjacent girders is proposed to control DSR. The rationality of the finite element model used is verified by comparing the numerical results with the experimental ones, showing a satisfactory agreement. Comparing the seismic response of a bridge model considering the subgrade-track constraints (BCTM) and a bridge model without subgrade-track constraints (BWTM), it is found that the DSR in the longitudinal distribution causes some new disadvantages, which are neglected in BWTM. The BCTM considering DLC generates a model called BCDM. The effect of the number of span on DSR are studied based on BCDM. The analysis of this model showed that DLC suppresses the DSR and reduces the seismic response of most bridge components. It also transfers the seismic disadvantage from the bridge part to the subgrade-track structure. As it is more convenient and cost-effective to repair the base plate of the subgrade than the bridge components after earthquake seismic event, this disadvantage transfer is in favor of forming a new anti-seismic system that subgrade-track structure is used to protect the bridge part.