Dynamic responses of a vehicle–bridge–soil interaction system subjected to stochastic-type ice loads

2022 ◽  
pp. 1-20
Author(s):  
Tianyu Wu ◽  
Wenliang Qiu ◽  
Chul-Woo Kim ◽  
Kai-Chun Chang ◽  
Xuzhao Lu
Keyword(s):  
Dynamic Responses ◽  
Interaction System ◽  
Ice Loads

Dynamic Response Analysis of Bridge Pier Subject to Earthquake and Ice Loads

2011 ◽  
Vol 250-253 ◽  
pp. 2211-2215
Author(s):  
Fu Qiang Qi
Keyword(s):  
Dynamic Response ◽  
Dynamic Equilibrium ◽  
Work Conditions ◽  
Bridge Pier ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Analysis Method ◽  
Equilibrium Equations ◽  
Different Types ◽  
Ice Loads

In order to discuss the effect of earthquake and dynamic ice loads to a bridge pier, this paper considered the effect of added mass of dynamic water, and it deduced the dynamic equilibrium equations for a bridge pier subject to earthquake and dynamic ice loads on the basis of nonlinear Morision equation. Using numerical analysis method, it discussed the dynamic response of a bridge pier subject to different types of earthquake loads, forced ice loads, and both earthquake and forced ice loads. Through comparing the pier responses in different work conditions, it discovered that the dynamic responses of the bridge pier subject to forced dynamic ice loads rise and fall severely at the time of ice buckling broken periodic change. The coupling effects of forced dynamic ice loads and earthquake especially near-fault earthquake enhance the dynamic response of bridge pier significantly.

Transient Dynamic Responses of an Integrated Air-Liquid-Elastic Tank Interaction System Subject to Earthquake Excitations

2008 ◽  
Author(s):  
Ye Ping Xiong ◽  
Jing Tang Xing
Keyword(s):  
Dynamic Behaviour ◽  
Liquid Sloshing ◽  
Dynamic Responses ◽  
Design Stage ◽  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Transient Dynamic ◽  
Interaction System ◽  
Three Phase ◽  
Elastic Tank

Sloshing problems in partially filled tanks are of increasing concerns in many engineering fields such as marine, chemical, aerospace engineering and automobile industry. The interactive dynamic behaviour of liquid and tank due to their interaction under various loading conditions can have vital impact on the integrity and safe operation of the system. Studies of liquid sloshing and its dynamic effect on the containers are necessary in the early design stage. Currently, most investigations on sloshing problems mainly focus on the analysis of liquids in rigid tanks where the fluid-structure interactions were neglected. Studies on fluid-structure interactions are limited to two phases of liquid-tank interactions. Three phase interactions involving air, liquid and elastic tank are rarely considered. In this paper, the dynamic behaviour of an air-liquid-elastic tank interaction system is investigated. The tank filled with air and liquid is supported at four equally spaced positions around the outer shell. The dynamic pressure in the liquid / air and the displacement in the elastic solid are used as variables to formulate the numerical model incorporating a substructure-subdomain approach and numerical simulations are presented based on a developed computer program. The natural frequencies in association with the corresponding vibration modes and the transient dynamic responses of the complex coupled system subject to earthquake excitations are presented. The ground motion data recorded from El-Centro earthquake is used as an earthquake load to the system. Different interactive cases are examined. These include liquid sloshing in a rigid tank, air-liquid interactions in a rigid tank, liquid-elastic tank interactions and three phase air-liquid-tank interactions. The numerical results obtained reveal the complex coupled behaviour of the system as well as the air effect on dynamic displacement and sloshing pressure. This study provides information for the design of liquid / gas filled tanks in which sloshing behaviour is of interest.

Dynamic Properties of Coupled Train-Bridge Interaction System

2014 ◽  
Vol 1065-1069 ◽  
pp. 875-881
Author(s):  
Xue Tong Si ◽  
Ke Jian Chen ◽  
Wen Hua Guo
Keyword(s):  
Finite Element ◽  
Coupling Effect ◽  
Dynamic Properties ◽  
Coupled System ◽  
Dynamic Responses ◽  
Plate Model ◽  
Lateral Direction ◽  
Long Span ◽  
Interaction System ◽  
Spatial Beam

This paper investigates the dynamic properties of each sub-system of a coupled railway train-bridge interaction system. Both spatial beam-plate model and spatial grillage model are built for a long-span dual-deck cable-stayed railway bridge by use of finite element method. The railway train is modeled as a mass-spring-damper system. Then free vibration equations are established based on the finite element models and then subspace iteration method is employed to calculate the dynamic properties for each sub-system. Results show that the spatial grillage model agrees well with the spatial beam-plate model in terms of mass and stiffness distribution. The spatial beam-plate model serves as benchmark solution and the grillage model as a tool for dynamic responses of the coupled system due to its computational efficiency. It also shows that first modes of both the railway train and long-span bridge are lateral direction, which indicates that the train may experience much response in lateral direction. Therefore attention should be drawn to the lateral running stability and safety of railway train due to the coupling effect between the bridge and railway train.

scholarly journals Formulation of Equations of Motion for a Simply Supported Bridge under a Moving Railway Freight Vehicle

2007 ◽  
Vol 14 (6) ◽  
pp. 429-446 ◽  
Author(s):  
Ping Lou ◽  
Qing-yuan Zeng
Keyword(s):  
Equations Of Motion ◽  
Contact Forces ◽  
Dynamic Responses ◽  
Railway Track ◽  
Time Step ◽  
Bogie Frame ◽  
Simply Supported ◽  
Car Body ◽  
Railway Freight ◽  
Interaction System

Based on energy approach, the equations of motion in matrix form for the railway freight vehicle-bridge interaction system are derived, in which the dynamic contact forces between vehicle and bridge are considered as internal forces. The freight vehicle is modelled as a multi-rigid-body system, which comprises one car body, two bogie frames and four wheelsets. The bogie frame is linked with the car body through spring-dashpot suspension systems, and the bogie frame is rigidly linked with wheelsets. The bridge deck, together with railway track resting on bridge, is modelled as a simply supported Bernoulli-Euler beam and its deflection is described by superimposing modes. The direct time integration method is applied to obtain the dynamic response of the vehicle-bridge interaction system at each time step. A computer program has been developed for analyzing this system. The correctness of the proposed procedure is confirmed by one numerical example. The effect of different beam mode numbers and various surface irregularities of beam on the dynamic responses of the vehicle-bridge interaction system are investigated.

The Effects on Facilities and Crew Members of the Ice-Resistant Platforms Induced by Ice Vibrations in Bohai Sea

2012 ◽  
Author(s):  
Dayong Zhang ◽  
Qianjin Yue ◽  
Huihui Li ◽  
Yanan Huang
Keyword(s):  
Optimization Design ◽  
Bohai Sea ◽  
Major Effect ◽  
Dynamic Responses ◽  
Structural Vibration ◽  
Pipeline System ◽  
Current Design ◽  
Human Fatigue ◽  
Ice Loads ◽  
Ice Resistance

The current design and safety assessment of ice-resistance platforms have usually been considered the maximum bearing capacity under the extreme static ice loads. However, the effects on the facilities and crew members induced by the dynamic ice loads are not been considered, and the risks are greater than the structure security. So it is necessary to analyze the effect on the facilities and crew members by ice-induced vibrations. Based on the data monitored on the platforms in the Bohai Sea and the ISO standard about human body in vibration environment, human fatigue on the platforms is evaluated. The typical history curve of the deck acceleration is obtained and used to analyze the excitation of pipelines. A mechanical model of structural vibration of pipeline system is developed. With finite element modeling, the dynamic responses of the pipeline systems induced by deck vibration are calculated. The results show ice-induced vibration may have major effect on the crew members and the facilities, and this failure mode by strongly ice-induced accelerations should be considered in safety producing of the existing platforms and optimization design of the new platforms.

Dynamic Behavior of Transmission Tower-Line Systems Subjected to Insulator Breakage

2018 ◽  
Vol 18 (03) ◽  
pp. 1850036 ◽  
Author(s):  
Jia-Xiang Li ◽  
Hong-Nan Li ◽  
Xing Fu
Keyword(s):  
Parametric Analysis ◽  
Failure Process ◽  
Element Model ◽  
Dynamic Responses ◽  
Span Length ◽  
Transmission Tower ◽  
Line System ◽  
Ice Load ◽  
Dynamic Analyses ◽  
Ice Loads

Ice loads attached to a transmission tower-line system can not only increase the vertical loads on the insulators, but also cause flashover to occur more easily. Both effects can lead to an increased probability of insulator breakage. In this paper, a finite-element model of a transmission tower-line system with three towers and four span lines under the ice loads is established. Dynamic analyses of the tower-line system after insulator breakage are performed to study the dynamic responses of the system and its failure process. In addition, a parametric analysis is conducted to investigate the influence of span length and insulator length on the vibration of the system and the failure mode. The results show that a larger ice load can lead to more severe vibration of the tower-line system due to the insulator breakage. Moreover, as the span length increases, the insulator breakage can result in more serious consequences and even the cascading collapse of the transmission tower-line system. This study provides crucial reference for preventing the failure of transmission tower-line systems in heavy ice regions.

Numerical Simulations of a Building-Acoustic Volume Interaction System Excited by Multiple Human Footfall Impacts

2008 ◽  
Author(s):  
Jing Tang Xing ◽  
Ye Ping Xiong
Keyword(s):  
Finite Element ◽  
Variational Formulation ◽  
Impact Load ◽  
Mixed Finite Element ◽  
Moving Load ◽  
Mixed Finite Element Method ◽  
Dynamic Responses ◽  
Experimental Result ◽  
Structure Interaction ◽  
Interaction System

A mixed finite element method is used to simulate a building structure-acoustic volume interaction system subject to multiple human footfall impacts. The pressure in the acoustic volume and the displacement of the structure are chosen as the fundamental variables to describe air-structure interaction dynamics. The governing equations and the corresponding variational formulation for generalised air-structure interaction systems are presented. From the variational formulation, the finite element and substructure-subdomain equations are derived. The available experimental results of footfall impact load histories are described and discussed. Based on an experimental result, an approximate footfall load time function is proposed to model the footfall loads in two successive human foot-steps. This approximate footfall load is applied at each structure point at which a left or right foot contacts at the corresponding time instant. Therefore, this footfall load is a moving load with a speed equalling the human walking speed. Following a generalised description of the developed numerical approach and footfall loads, an example is given. In this example, three cases involving two people walking along two perpendicular directions on the top floor of the structure are simulated, respectively. The dynamic responses of the displacement of the structure and the acoustic pressure in the acoustic volume are obtained. The calculated results are compared and discussed to illustrate the developed method and to reveal the mechanism of low-frequency vibration produced by human footfall impacts. The advantages of the proposed method are summarised to provide some guidelines to house designs.

scholarly journals Safety evaluation of a vehicle–bridge interaction system using the pseudo-excitation method

2021 ◽  
Author(s):  
Nan Zhang ◽  
Ziji Zhou ◽  
Zhaozhi Wu
Keyword(s):  
High Speed ◽  
Safety Evaluation ◽  
Dynamic Responses ◽  
Safety Factors ◽  
Pseudo Excitation Method ◽  
Creep Theory ◽  
Interaction System ◽  
Bridge Responses ◽  
Pseudo Excitation ◽  
Excitation Method

AbstractA method for analysing the vehicle–bridge interaction system with enhanced objectivity is proposed in the paper, which considers the time-variant and random characteristics and allows finding the power spectral densities (PSDs) of the system responses directly from the PSD of track irregularity. The pseudo-excitation method is adopted in the proposed framework, where the vehicle is modelled as a rigid body and the bridge is modelled using the finite element method. The vertical and lateral wheel–rail pseudo-excitations are established assuming the wheel and rail have the same displacement and using the simplified Kalker creep theory, respectively. The power spectrum function of vehicle and bridge responses is calculated by history integral. Based on the dynamic responses from the deterministic and random analyses of the interaction system, and the probability density functions for three safety factors (derailment coefficient, wheel unloading rate, and lateral wheel axle force) are obtained, and the probabilities of the safety factors exceeding the given limits are calculated. The proposed method is validated by Monte Carlo simulations using a case study of a high-speed train running over a bridge with five simply supported spans and four piers.

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

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