Experimental study on stiffness degradation of Crts Ⅱ ballastless track-bridge structural system under fatigue train load

2021 ◽  
Vol 283 ◽  
pp. 122794
Author(s):  
Ling-Yu Zhou ◽  
Lei Zhao ◽  
Akim D. Mahunon ◽  
Ying-Ying Zhang ◽  
Hua-Yong Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Stiffness Degradation ◽  
Structural System ◽  
Ballastless Track ◽  
Track Bridge

Experimental study on CRTS Ⅱ ballastless track-bridge structural system mechanical fatigue performance

2021 ◽  
Vol 244 ◽  
pp. 112784
Author(s):  
Lei Zhao ◽  
Lingyu Zhou ◽  
Zhiwu Yu ◽  
Akim D. Mahunon ◽  
Xiusheng Peng ◽  
...  
Keyword(s):  
Experimental Study ◽  
Fatigue Performance ◽  
Structural System ◽  
Mechanical Fatigue ◽  
Ballastless Track ◽  
Track Bridge

scholarly journals Laboratory Investigation of the Temperature-Dependent Mechanical Properties of a CRTS-Ⅱ Ballastless Track-Bridge Structural System in Summer

2020 ◽  
Vol 10 (16) ◽  
pp. 5504
Author(s):  
Lingyu Zhou ◽  
Yahui Yuan ◽  
Lei Zhao ◽  
Akim Djibril Gildas Mahunon ◽  
Lifan Zou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Relative Displacement ◽  
Railway Track ◽  
Structural System ◽  
Depth Direction ◽  
Ballastless Track ◽  
Track System ◽  
Track Bridge ◽  
Structural Strain

To study the mechanical properties of the China Railway Track System type II (CRTS-II) ballastless slab track structure, a 1/4-scale specimen of a CRTS-II slab ballastless track-32-m standard prefabricated simply supported box girder bridge with three spans and two high-speed railway lines was developed. The mechanical properties of the structure under the action of daily natural temperatures were studied under the natural environmental conditions. The structural strain and relative interlayer displacements were analyzed. The results show that the temperature of the CRTS-II ballastless track-bridge structural system changes periodically every 24 h. The strain of the structural layers of the track system first increases and then decreases sinusoidally, and the internal strain of the track system lags along the vertical depth direction. The relative displacement between the layers of the ballastless track bridge structure system increases with the increase in temperature. The extreme value of the vertical relative displacement appears between the track bed and the bridge at section 1/4 in the span, so it should be paid attention to by the maintenance personnel. Due to the constraint of the shear slots, the structural strain and relative displacement at the fixed end near the shear slots are smaller than those at the sliding end. The mid-span deflection is the largest, and the overall deflection during the cooling phase is more significant than that during the heating phase.

scholarly journals Investigation of the Fatigue Behaviour of a Ballastless Slab Track–Bridge Structural System under Train Load

2019 ◽  
Vol 9 (17) ◽  
pp. 3625 ◽  
Author(s):  
Lingyu Zhou ◽  
Linqi Yang ◽  
Zhi Shan ◽  
Xiusheng Peng ◽  
Akim D. Mahunon
Keyword(s):  
Cohesive Zone Model ◽  
Simulation Analysis ◽  
Fatigue Loading ◽  
Element Model ◽  
Interface Layer ◽  
Railway Track ◽  
Zone Model ◽  
Structural System ◽  
Ballastless Track ◽  
Track Bridge

To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to the interface layer, a three-dimensional nonlinear finite element model of the China Railway Track System Type II (CRTS II) ballastless track–bridge structural system was established using the equivalent static method. Then, using this model, we developed the numerical simulation analysis of the influence law of material damage deterioration on structural system performance under train load and revealed the fatigue evolution of the structural system. The results show that the beam remains in compressed status for the whole process, the track is in compression in the midspan and in tension at the beam end, and the tensile stress is larger near the shear groove under the double-track static load. Under the fatigue load, stiffness degradation of the structural system is not obvious, and integral rigidity of the structural system is dependent on the rigidity of the beam. Strength reduction of the materials caused stress redistribution of the structural system and had a larger effect on the stress of each layer of track structure than on the stress on the beam. The fatigue degradation of the cement-emulsified asphalt (CA) mortar layer material has a significant impact on the structural system, which directly affects structural layer stress variation with the fatigue loading cycle.

scholarly journals Performance of CRTS-II Ballastless Track–Bridge Structural System Rebars under Fatigue Loading Test

2021 ◽  
Vol 11 (11) ◽  
pp. 4858
Author(s):  
Lingyu Zhou ◽  
Lifan Zou ◽  
Lei Zhao ◽  
Yahui Yuan ◽  
Akim D. Mahunon ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatigue Damage ◽  
Strain Amplitude ◽  
Amplitude Ratio ◽  
Strain Curve ◽  
Fatigue Loading ◽  
Structural System ◽  
Ballastless Track ◽  
Cumulative Strain ◽  
Track Bridge

To study the evolution of mechanical properties of steel rebars in the China Railway Track System Type II (CRTS II) ballastless track–bridge structural system under repeated train loads, a 1/4 scale three-span ballastless slab track simple-supported bridge structural system specimen was manufactured and subjected to a multistage fatigue test with 18 million cycles. The experimental results show that the strain amplitude of the steel bar changes proportionally to the fatigue stress amplitude, and there is an obvious strain increase in the loading stage 4, where the fatigue stress amplitude is the largest. During the test, the cumulative strain–amplitude ratio first decreases then increases. At the end of the test, the cumulative strain–amplitude ratio increases by 5.46% and 5.32%, respectively, at L/2 and L/4 sections. The load–strain curve of the steel rebar keeps the shape of an oblique straight line. The slope increases first and then decreases with a degradation at the end of the test of 5.14% and 4.82%, respectively, at L/2 and L/4 sections. The mechanical properties of the rebar are enhanced under the first three million fatigue loading cycles: this is the fatigue strengthening stage. The mechanical properties of reinforcement gradually degrade from the three millionth cycle to the end of the test: this is the fatigue damage stage. Finally, based on the material fatigue damage model and the multistage cumulative damage criterion, the change rule of the load–strain curve slope of steel rebars in the fatigue damage stage is obtained by finite element simulation. The simulation results agree well with the experimental data, proving the validity of the calculation method proposed in this paper.

Stiffness degradation of shear walls under cyclic loading: experimental study and modelling

2019 ◽  
Vol 17 (9) ◽  
pp. 5183-5216 ◽  
Author(s):  
Xiangyong Ni ◽  
Shuangyin Cao ◽  
Yizhu Li ◽  
Shuai Liang
Keyword(s):  
Experimental Study ◽  
Cyclic Loading ◽  
Shear Walls ◽  
Stiffness Degradation

scholarly journals Analysis of the Vibration Characteristics of Ballastless Track on Bridges Using an Energy Method

2020 ◽  
Vol 10 (7) ◽  
pp. 2289 ◽  
Author(s):  
Hanwen Jiang ◽  
Liang Gao
Keyword(s):  
Energy Method ◽  
High Speed ◽  
Power Flow ◽  
Evaluation Method ◽  
Flow Theory ◽  
Vibration Characteristics ◽  
Vibration Energy ◽  
Ballastless Track ◽  
Track Bridge ◽  
Bridge System

Although the high-speed railway (HSR) system has been widely agreed to be a sustainable and convenient means of transportation, the vibration induced has already been deemed an urgent environmental problem. For the sake of investigating the vibration characteristics of the ballastless track on bridges in the HSR system from the point of view of energy, a numerical model of the vehicle–track–bridge coupled system is developed herein and the energy method based on power flow theory is employed. In addition, a corresponding evaluation method of the power flow theory is developed to evaluate the vibration characteristics of the track–bridge system. The conclusions indicate that (1) the vibration energy gradually attenuates from top to bottom of the track–bridge system in its transfer process. Moreover, the attenuation effects are mainly the result of the elasticity and damping effects of the fasteners and the slab mat layer. (2) With increasing slab mat layer stiffness, the vibration energy of the rail slightly decreases; on the contrary, that of the slab track and the bridge obviously increases. (3) With increasing fastener stiffness, the vibration energy of the entire track–bridge system increases. (4) With increasing running speed, the vibration energy of the entire track–bridge system rises obviously. The results reveal that the reasonable stiffness levels of the fasteners and the slab mat layer are 40 to 60 kN/mm and 40 to 60 MPa/m, respectively, under the investigated condition in this work. This work also presents a novel way to study the vibration characteristics of the ballastless track on bridges of HSRs in terms of energy.

scholarly journals Vertical Dynamic Analysis of Ballastless Tracks on Train-Track- Bridge System

2020 ◽  
Vol 306 ◽  
pp. 02003
Author(s):  
Haoran Xie ◽  
Bin Yan ◽  
Jie Huang
Keyword(s):  
Track Structure ◽  
Vertical Acceleration ◽  
Train Track ◽  
Steel Spring ◽  
Slab Track ◽  
Ballastless Track ◽  
Track System ◽  
Train Speed ◽  
Track Bridge ◽  
Bridge System

In order to investigate the vertical dynamic response characteristics of train-track-bridge system on CWR (Continunously Welded Rail) under dynamic load of train on HSR (High-Speed Railway) bridge. Based on the principle of vehicle train-track-bridge coupling dynamics, taking the 32m simply supported bridge of a section of Zhengzhou-Xuzhou Passenger Dedicated Line as an example, the finite element software ANSYS and the dynamic analysis software SIMPACK are used for co-simulation, and bridge model of the steel spring floating slab track and the CRTSIII ballastless track (China Railway Track System) considering the shock absorbing steel spring, the limit barricade and the contact characteristics of track structure layers are established. On this basis, in order to study the dynamic response laws of the design of ballastless track structure parameters to the system when the train crosses the bridge and provide the basis for the design and construction, by studying the influence of the speed of train on the bridge, the damage of fasteners and the parameters of track structure on the train-track-bridge system, the displacement of rail, vertical vibration acceleration and wheel-rail force response performance are analyzed. Studies have shown that: At the train speed of 40 km/h, the displacement and acceleration of the rail and track slab in the CRTSIII ballastless track are smaller than the floating slab track structure, but the floating slab track structure has better vibration reduction performance for bridges. The acceleration of rail, track slab and bridge increases obviously with the increase of train speed, the rail structure has the largest increasement. Reducing the stiffness of fasteners could decrease the vertical acceleration response of the steel spring floating slab track system, the ability to absorb shock can be enhanceed by reducing the stiffness of the fastener appropriately. Increasing the density of the floating slab can increase the vertical acceleration of the floating slab and the bridge, thereby decreasing the vibration amplitude of the system.

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