scholarly journals Stochastic Analysis on the Resonance of Railway Trains Moving over a Series of Simply Supported Bridges

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tao Zhang ◽  
Taimu Jin ◽  
Jun Luo ◽  
Shengyang Zhu ◽  
Kaiyun Wang
Keyword(s):  
Stochastic Analysis ◽  
Degrees Of Freedom ◽  
Representative Point ◽  
Superposition Method ◽  
Point Sets ◽  
Coupled Dynamics ◽  
Simply Supported ◽  
Probability Density Evolution Method ◽  
Multiple Vehicles ◽  
Track Bridge

Resonance problems encountered in vehicle-bridge interaction (VBI) have attracted widespread concern over the past decades. Due to system random characteristics, the prediction of resonant speeds and responses will become more complicated. To this end, this study presents stochastic analysis on the resonance of railway trains moving over a series of simply supported bridges with consideration of the randomness of system parameters. A train-slab track-bridge (TSB) vertically coupled dynamics model is established following the basic principle of vehicle-track-coupled dynamics. The railway train is composed of multiple vehicles, and each of them is built by seven rigid parts assigned with a total of 10 degrees of freedom. The rail, track slab, and bridge are considered as Euler–Bernoulli beams, and the vibration equations of which are established by the modal superposition method (MSM). Except for the nonlinear wheel-rail interaction based on the Hertz contact theory, the other coupling relations between each subsystem are assumed to be linear elastic. The number theory method is employed to obtain the representative sample point sets of the random parameters, and the flow trajectories of probabilities for the TSB dynamics system are captured by a probability density evolution method (PDEM). Numerical results indicate that the maximum bridge and vehicle responses are mainly dominated by the primary train-induced resonant speed; the last vehicle of a train will be more seriously excited when the bridges are set in resonance by the train; the resonant speeds and responses are rather sensitive to the system randomness, and the possible maximum amplitudes predicted by the PDEM are significantly underestimated by the traditional deterministic method; optimized parameters of the TSB system are preliminary obtained based on the representative point sets and imposed screening conditions.

A Stochastic Semi-Physical Model of Seismic Ground Motions in Time Domain

2018 ◽  
Vol 12 (03) ◽  
pp. 1850006 ◽  
Author(s):  
Yanqiong Ding ◽  
Yongbo Peng ◽  
Jie Li
Keyword(s):  
Probability Density ◽  
Ground Motions ◽  
Seismic Source ◽  
Response Spectra ◽  
Propagation Path ◽  
Superposition Method ◽  
Probability Density Evolution Method ◽  
Proposed Model ◽  
Time Histories ◽  
Seismic Accelerations

A stochastic function model of seismic ground motions is presented in this paper. It is derived from the consideration of physical mechanisms of seismic ground motions. The model includes the randomness inherent in the seismic source, propagation path and local site. For logical selection of the seismic acceleration records, a cluster analysis method is employed. Statistical distributions of the random parameters associated with the proposed model are identified using the selected data. Superposition method of narrow-band wave groups is then adopted to simulate non-stationary seismic ground motions. In order to verify the feasibility of the proposed model, comparative studies of time histories and response spectra of the simulated seismic accelerations against those of the recorded seismic accelerations are carried out. Their probability density functions, moreover, are readily investigated by virtue of the probability density evolution method.

Big data based research on the management system framework of ideological and political education in colleges and universities

2020 ◽  
pp. 1-10
Author(s):  
Yuejun Xia
Keyword(s):  
Artificial Intelligence ◽  
Data Mining ◽  
Big Data ◽  
Ideological And Political Education ◽  
Political Education ◽  
Representative Point ◽  
Point Sets ◽  
Mining Technology ◽  
Education Management ◽  
Intelligence System

Artificial intelligence model combined with data mining technology can mine useful data from college ideological and political education management, and conduct process evaluation and teaching management. Therefore, based on the superiority of data mining technology and artificial intelligence system, this paper improves the traditional algorithm and constructs a university ideological and political education management model based on big data artificial intelligence. Moreover, this study uses a local sensitive hash function to generate representative point sets and uses the generated representative point sets for clustering operations. In order to verify the performance of the algorithm model, a control experiment is designed to compare the algorithm of this paper with traditional data mining methods. It can be seen from the research results that the algorithm model constructed in this paper has good performance and can be applied to practice.

Effect of Prestress on Bridge–Vehicle Interactions

2015 ◽  
Author(s):  
Hai Zhong ◽  
Mijia Yang
Keyword(s):  
Degrees Of Freedom ◽  
Virtual Work ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Principle Of Virtual Work ◽  
Vehicle Model ◽  
Multiple Vehicles ◽  
4 Degrees Of Freedom

Prestress applied on bridges affects the dynamic interaction between bridges and vehicles traveling over them. In this paper, the prestressed bridge is modeled as a beam subjected to eccentric prestress force at the two ends, and a half-vehicle model with 4 degrees of freedom is used to represent the vehicle passing the bridge. A new bridge–vehicle interaction model considering the effect of prestress with eccentricity is developed through the principle of virtual work. The correctness and accuracy of the model are validated with literature results. Based on the developed model, numerical simulations have been conducted using the Newmark’s β method to study the effects of vehicle speed, eccentricity and amplitude of the prestress, and presence of multiple vehicles. It is shown that prestress has an important effect on the maximum vertical acceleration of vehicles, which may provide a good index for detecting the change of prestress. It is also interesting to find that the later-entering vehicle on the prestressed bridge will largely reduce the maximum vertical acceleration of the vehicle ahead of it.

scholarly journals Analysis of Longitudinal Force of Beam and Rail of Continuously Welded Rails (CWR) on Railway Bridge

2022 ◽  
Vol 2148 (1) ◽  
pp. 012065
Author(s):  
Zhiping Zeng ◽  
Ji Hu ◽  
Qiang Zeng ◽  
Zhibin Huang ◽  
Huatuo Yin ◽  
...  
Keyword(s):  
Element Model ◽  
Longitudinal Force ◽  
Relative Displacement ◽  
Railway Bridge ◽  
Simply Supported ◽  
Maximum Value ◽  
Constant Resistance ◽  
Left And Right ◽  
The Right ◽  
Track Bridge

Abstract To study the longitudinal force of CWR on viaduct, a track-bridge-pier finite element model is established. Taking a multi-span simply supported beam with a maximum span of 32.7m of an elevated CWR as an example, the additional expansion and contraction forces, displacement between rail and beam and the force of pier are calculated, and whether the rail stress meets the requirements when setting constant resistance fasteners is checked. The results show that: (1) For the left and right lines, the maximum additional expansion forces of single strand rail are both 211.13kN, and the maximum relative displacements between beam and rail are both 6.572mm. (2) The maximum value of the additional expansion and contraction forces and the relative displacement between beam and rail of the same line occur at the same position. The left line is at ZFZ29 pier and the right line is at ZFS31 pier. (3) The maximum force of pier in this section is 500.80kN, and the pier numbers are ZFZ27 and ZFS29. (4) The rail stress is less than the allowable stress of 352MPa, and the rail strength meets the requirements.

Vortex-Induced Vibration of a Spherical Body With Free Surface Effects: Application to Tugboats With Low Length-to-Beam Ratio

2020 ◽  
Author(s):  
A. Chizfahm ◽  
V. Joshi ◽  
R. K. Jaiman
Keyword(s):  
Free Surface ◽  
Vortex Shedding ◽  
Degrees Of Freedom ◽  
Nonlinear Dynamical System ◽  
Open Water ◽  
Surface Effects ◽  
Spherical Body ◽  
Wake Flow ◽  
Coupled Dynamics ◽  
Fluid Structure

Abstract Flow-structure interactions of submerged or floating bodies can lead to undesired behavior in many marine and offshore engineering applications. In this paper, we consider a complex nonlinear dynamical system of unsteady wake flow interacting with a freely moving tugboat in open water. To meet the operational demands of compact, agile, and high power ship-handling, new hull forms of tugboats are designed with low length-to-beam ratios and rounded sterns. While the hydrodynamic design with low length-to-beam ratios provides improved directional controllability, it can be challenging for tractor tugboats due to the massively separated wake flow with the vortex shedding. These wake vortices can cause large fluctuating yaw moments and possibly a strong fluid-structure coupling via synchronization or lock-in. Of particular interest, the proposed study will focus on the physical mechanism and control of flow-induced oscillations with free-surface effects via our in-house fully-coupled three-dimensional fluid-structure-free-surface interaction solver. Stabilized finite element based methods will be employed to discretize the partial differential equations that arise from the mathematical modeling of the physical phenomena considered. We will begin with a fundamental understanding of coupled dynamics of a canonical geometry of a freely vibrating sphere at free-surface. The physical insight gained will then be applied to a realistic tugboat configuration. We aim to understand the fundamentals of vortex-shedding modes and the coupled dynamics pertaining to the flow-induced vibration (FIV) response of a freely vibrating sphere (a prototypical problem for a rounded tugboat) in all three spatial directions. To predict and analyze the vortex synchronization regimes and the wake patterns, the FIV response of the sphere at a low mass ratio is investigated over a broad range of reduced velocities and Reynolds numbers. We find that the sphere begins to move along a linear trajectory with hairpin vortex-shedding mode, eventually transforming into a circular trajectory with spiral mode in its stationary state for Re ∈ [2000–6000]. We systematically examine these mode transitions and the motion trajectories in the three degrees-of-freedom for higher Reynolds number up to 15,000 which has not been studied in detail in the literature. Finally, we will look into the effect of free surface on the FIV response of the sphere piercing the free surface and will link our fundamental results with a realistic configuration of tugboat undergoing vortex-induced oscillation with free surface effects.

Analytical Solutions Using a Higher-Order Refined Theory for the Static Analysis of Functionally Graded Material Plates

2013 ◽  
Vol 705 ◽  
pp. 30-35
Author(s):  
K. Swaminathan ◽  
D.T. Naveenkumar
Keyword(s):  
Shear Deformation ◽  
Static Analysis ◽  
Functionally Graded Material ◽  
Analytical Solutions ◽  
Degrees Of Freedom ◽  
Order Theory ◽  
Higher Order ◽  
Functionally Graded ◽  
Simply Supported ◽  
Graded Material

Analytical formulations and solutions to the static analysis of simply supported Functionally Graded Material (FGM) plates hitherto not reported in the literature based on a higher-order refined shear deformation theory with nine degrees-of-freedom already reported in the literature are presented. This computational model incorporates the plate deformations which account for the effect of transverse shear deformation. The transverse displacement is assumed to be constant throughout the thickness. In addition, another higher order theory with five degrees-of-freedom and the first order theory already reported in the literature are also considered for comparison. The governing equations of equilibrium using all the computational models are derived using the Principle of Minimum Potential Energy (PMPE) and the analytical solutions are obtained in closed-form using Naviers solution technique. A simply supported plate with SS-1 boundary conditions subjected to transverse loading is considered for all the problems under investigation. The varying parameters considered are the side-to-thickness ratio, power law function, edge ratio and the degree of anisotropy. Correctness of the formulation and the solution method is first established and then extensive numerical results using all the models are presented which will serve as a bench mark for future investigations.

Accurate Analytical-Type Solutions for the Free Vibration of Simply-Supported Parallelogram Plates

1991 ◽  
Vol 58 (1) ◽  
pp. 203-208 ◽  
Author(s):  
D. J. Gorman
Keyword(s):  
Free Vibration ◽  
Equal Length ◽  
Superposition Method ◽  
Vibration Modes ◽  
Type Solution ◽  
Simply Supported ◽  
Wide Range ◽  
Plate Geometry ◽  
Special Case ◽  
Comprehensive Study

A comprehensive study of the free vibration of simply-supported parallelogram plates is conducted. Solutions are obtained by utilizing the superposition method and by taking advantage of symmetry inherent in the problem. Toward this end a new alternating Le´vy-type solution is introduced. Verification tests are conducted by comparing computed eigenvalues with those of rhombic plates in the special case where all plate edges are of equal length. Eigenvalues are stored for eight vibration modes and for a wide range of plate geometry.

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