Capacity Analysis of Railway Concrete Sleeper

Railway is one of the most important reliable and widely used means of transportation and it convey freight, passengers, minerals, grain, etc and its infrastructure has been regaining their importance due to their efficiency and environmentally friendly technologies. This leads to increasing the train axel load, vehicle speed, track structure capacity and more frequent train usage. The demand for rail transport is derived with the possible exception of sight-seeing, people travel to satisfy another need at their destination and this increase the rail demand transportation. To accommodate the increase in rail demand, trac council council k structure is constructing a new railway line or improving the existing railroad structure. Upgrading the existing structure will increase its capacity and improving the existing structure more durable and reliable means of transportation. These improve the service provision to brought new challenge to the old railway track engineering. This challenge demanded for a better understanding of both static and dynamic response of track structure. Due to different loading condition, poor maintenance of the sleeper or poor quality of the ballast, unbalanced load distribution along the sleeper-ballast interference may occur. The Structural analysis of existing sleeper is carried out by using finite element method. The finite element analysis include dynamic and general static analysis. The parametric optimization of pre-stressed concrete sleeper is focused on increasing the capacity of the existing sleeper design through an investigation on pre-stress type, quantity, configuration, stress level and other materials properties. The study of parametric optimization indicate that increasing the existing sleeper capacity by changing the strand tendon diameter and compressive concrete strength. Keywords: At transfer, at service, Jacking force, Pretension, Transfer length, Development length

Behaviour of pre-stressed high strength concrete sleepers subjected to dynamic loads

As part of ballasted railway track, pre-stressed concrete sleepers (PCSs) play an essential role in track response, performance and safety. PCSs are subjected to dynamic loads which are often high magnitude and low duration. The characteristics of dynamic loads, the interactions between track components and the dynamic responses of PCSs under dynamic loads have been vastly investigated throughout past decades and continue to be a subject of interest to the railway industry.. Mechanical behaviours of PCSs such as dynamic response and failure mechanisms are important to meet the structural and durability requirements of railway sleepers. However, the influence of high performance concrete (HPC) mechanical properties on behaviour of PCSs is currently lacking. This paper presents a finite element model developed as a part of a broader investigation undertaken at the University of Melbourne. Finite element modelling package LS-DYNA has been used to represent a sleeper in a simulated track condition. The model is validated based on published experimental information. Different grades of high strength concrete (HSC) have been investigated. Mechanical properties such as compressive strength, tensile strengths, fracture energy and elastic modulus are considered.. The results show that the using higher concrete grade in sleeper leads to a larger bending moment under the same dynamic load. This confirms the inadequacy of current design approach for PCSs

Numerical and Experimental Vibration Analysis of a Steam Turbine Rotor Blade

Damage to the rotor blade of a steam turbine is a relatively common problem and is one of the leading causes of sudden and unplanned shutdowns of a steam turbine. Therefore, the high reliability of the rotor blades is very important for the safe and economical operation of the steam turbine. To ensure high reliability, it is necessary to perform a vibration analysis of the rotor blades experimentally and in a computer environment. In this paper, a modal analysis was performed on the twisted blade of the last stage of the turbine in the Ansys software. The results of the modal analysis of the stationary rotor blade were compared with the results obtained by the bump test, which confirmed the numerical model of the blade. A modal analysis of a rotating rotor blade was performed on the same numerical model, and Campbell diagrams were plotted to determine the critical speed

Static and modal analysis of wind turbine towers.

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Effects of Vibration Located on the Steel Truss Bridges Under Moving Load

Structural vibration control as an advanced technology in engineering consists of implementing energy dissipation devices or control systems into structures to reduce excessive structural vibration, enhance human comfort and prevent catastrophic structural failure due to strong winds and earthquakes, among other inputs. When the bridge carries heavy traffic, vibrations in the bridge structural elements subjected to high levels of stress. This tension bridge subjected to fatigue. This paper studies and focus the effects of vibration of steel truss bridges and finally to suggest future directions of research and innovation. The possibilities of modal properties of global and local vibration method in determining the structural changes in the truss bridges discussed located to the results of finite element analysis

Effects of Vibration Located on the Steel Truss Bridges under Moving Load

Structural vibration control as an advanced technology in engineering consists of implementing energy dissipation devices or control systems into structures to reduce excessive structural vibration, enhance human comfort and prevent catastrophic structural failure due to strong winds and earthquakes, among other inputs. When the bridge carries heavy traffic, vibrations in the bridge structural elements subjected to high levels of stress. This tension bridge subjected to fatigue. This paper studies and focus the effects of vibration of steel truss bridges and finally to suggest future directions of research and innovation. The possibilities of modal properties of global and local vibration method in determining the structural changes in the truss bridges discussed located to the results of finite element analysis

Wireless-based identification and model updating of a skewed highway bridge for structural health monitoring

Vibration-based monitoring was performed on a short-span skewed highway bridge on the basis of wireless measurements. By means of operational modal analysis, highly accurate modal results (frequencies and mode shapes) were extracted by using a self-developed wireless acquisition system, for which the performance was verified in the field. In order to reproduce the experimental modal characteristics, a refined finite element model was manually tuned to reduce the idealization errors and then updated with the sensitivity method to reduce the parametric errors. It was found that to build a reliable Finite element (FE) model for application in structural health monitoring, the effects of superelevation and boundary conditions of a skewed bridge should be taken into account carefully

3D FE modelling of composite box Girder Bridge

The complexity nature of composite box girder bridges makes it difficult to accurately predict their structural response under loading. However, that difficulty in the analysis and design of composite box girder bridges can be handled by the use of the digital computers in the design. An intricate geometry such as that of composite box girder bridges can be facilely modelled using the FE technique. The method is also capable of dealing with different material properties, relationships between structural components, boundary conditions, as well as statically or dynamically applied loads. The linear and nonlinear structural response of such bridges can be predicted with good accuracy using this method. A major interest in this paper is to perform three-dimensional FE analyses of composite box girder bridge to simulate the actual bridge behaviour. ANSYS FE package is used to develop the models which offer different element types and physical contact conditions between concrete deck and steel girder. Predictions of several FE models are assessed against the results acquired from a field test. Several factors are considered, and confirmed through experiments especially full shear connections which are obviously essential in composite box girder. Numerical predictions of both vertical displacements and normal stresses at critical sections fit fairly well with those evaluated experimentally. The agreement between the FE models and the experimental models show that the FE model can aid engineers in design practices of box girder bridges