Measurement and Prediction of the Pedestrian-Induced Vibrations of a Footbridge

2009 ◽  
Vol 40 (4) ◽  
pp. 10-19
Author(s):  
P. Van den Broeck ◽  
G. De Roeck ◽  
E. Reynders ◽  
D. Degrauwe ◽  
I. Bojidarova Georgieva ◽  
...  
Keyword(s):  
Prediction Method ◽  
Element Model ◽  
Vertical Acceleration ◽  
Load Model ◽  
Acceleration Level ◽  
Numerical Predictions ◽  
Vibration Serviceability ◽  
Increasing Trend ◽  
Series Of Experiments ◽  
Vertical Accelerations

Vibration serviceability has become an important issue in the design of modern slender footbridges with large spans. This paper presents the measurements and the numerical predictions of the footfall-induced vibrations of a pedestrian bridge. A series of experiments were carried out with different-sized groups crossing the bridge, varying in number from 10 up to 50 participants and recording the vertical and lateral accelerations at different locations on the bridge. Two types of tests were performed: free walking and synchronized walking by means of a metronome signal, recorded on a tape recorder carried by the group of students. The effect of the test type is analyzed and shows a magnitude in difference between the vertical accelerations caused by the free and the synchronized walking. The increasing trend of the acceleration levels with increasing group size is also clearly observed. A numerical prediction method is used to simulate the synchronized walking experiments based on an updated finite element model of the bridge and a single pedestrian load model. It is shown that the predicted acceleration level is sensitive to the assumptions made regarding the level of synchronization between the pedestrians and the magnitude of the dynamic load generated by each pedestrian. Taking into account these specific measurement conditions, a fair agreement is obtained between the predicted and the observed vertical acceleration levels at seven positions along the length of the footbridge.

scholarly journals Smartphone monitoring of in-ambulance vibration and noise

2021 ◽  
pp. 095441192098599
Author(s):  
Tom Partridge ◽  
Lorelei Gherman ◽  
David Morris ◽  
Roger Light ◽  
Andrew Leslie ◽  
...  
Keyword(s):  
Transport Systems ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Noise Levels ◽  
The Road ◽  
Neonatal Transport ◽  
Mass Data ◽  
Transport Team ◽  
Vertical Accelerations ◽  
Noise Vibration

Transferring sick premature infants between hospitals increases the risk of severe brain injury, potentially linked to the excessive exposure to noise, vibration and driving-related accelerations. One method of reducing these levels may be to travel along smoother and quieter roads at an optimal speed, however this requires mass data on the effect of roads on the environment within ambulances. An app for the Android operating system has been developed for the purpose of recording vibration, noise levels, location and speed data during ambulance journeys. Smartphone accelerometers were calibrated using sinusoidal excitation and the microphones using calibrated pink noise. Four smartphones were provided to the local neonatal transport team and mounted on their neonatal transport systems to collect data. Repeatability of app recordings was assessed by comparing 37 journeys, made during the study period, along an 8.5 km single carriageway. The smartphones were found to have an accelerometer accurate to 5% up to 55 Hz and microphone accurate to 0.8 dB up to 80 dB. Use of the app was readily adopted by the neonatal transport team, recording more than 97,000 km of journeys in 1 year. To enable comparison between journeys, the 8.5 km route was split into 10 m segments. Interquartile ranges for vehicle speed, vertical acceleration and maximum noise level were consistent across all segments (within 0.99 m . s−1, 0.13 m · s−2 and 1.4 dB, respectively). Vertical accelerations registered were representative of the road surface. Noise levels correlated with vehicle speed. Android smartphones are a viable method of accurate mass data collection for this application. We now propose to utilise this approach to reduce potential harmful exposure, from vibration and noise, by routing ambulances along the most comfortable roads.

Dynamic Characteristic Analysis of Irregularity under Turnout by Vehicle-Turnout Rigid-Flexible Coupling Model

2014 ◽  
Vol 945-949 ◽  
pp. 591-595 ◽  
Author(s):  
Meng Chen ◽  
Yan Yun Luo ◽  
Bin Zhang
Keyword(s):  
Finite Element ◽  
Longitudinal Direction ◽  
Element Model ◽  
Vertical Displacement ◽  
Coupling Model ◽  
Interaction Force ◽  
Vertical Acceleration ◽  
Characteristic Analysis ◽  
Flexible Coupling ◽  
Multi Body

Finite element model of track in frog zone is built by vehicle-turnout system dynamics. Considering variation of rail section and elastic support, bending deformation of turnout sleeper, spacer block and sharing pad effects, the track integral rigidity distribution in longitudinal direction is calculated in the model. Vehicle-turnout rigid-flexible coupling model is built by finite element method (FEM), multi-body system (MBS) dynamics and Hertz contact theory. With the regularity solution that different stiffness is applied for rubber pad under sharing pad of different turnout sleeper zone, analysis the variation of vertical acceleration of bogie and wheelset, rail vertical displacement and wheel-rail interaction force, this paper proves that setting reasonable rubber pad stiffness is an efficient method to solve rigidity irregularity problem.

Study on the Deformation of the Oil-Immersed Transformer Tank by FEA

2011 ◽  
Vol 422 ◽  
pp. 51-54 ◽  
Author(s):  
Jian Hua Zhang ◽  
Ling Yu Sun ◽  
Xiao Jun Zhang ◽  
Jia Peng Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mechanical Strength ◽  
Element Model ◽  
3D Finite Element ◽  
3D Finite Element Model ◽  
Series Of Experiments ◽  
Oil Tank ◽  
Directive Function

The oil-immersed transformer tank is an outside package component of the transformer body. The sealing quality and mechanical strength of the oil tank are affected by the deformation after loading. In this paper, the 3D finite element model of oil-immersed transformer tank is established. The oil-immersed transformer tank deformation is obtained by FEA under the condition of vacuuming. A series of experiments about the deformation of the oil-immersed transformer tank are carried out. Comparing experiment results with FEA results, FEA results are agrees well with the experiments’. It can save the time consumed on designing the oil tank, and has the directive function for the whole design.

scholarly journals Effect of spatial distribution of fibers on elastic properties of unidirectional carbon/carbon composites

2021 ◽  
Vol 309 ◽  
pp. 01214
Author(s):  
M.V.N Mohan ◽  
Ramesh Bhagat Atul ◽  
Vijay Kumar Dwivedi
Keyword(s):  
Finite Element ◽  
Spatial Distribution ◽  
Elastic Properties ◽  
Element Model ◽  
Experimental Methods ◽  
Design Stage ◽  
Carbon Composites ◽  
Numerical Predictions ◽  
Numerical Finite Element ◽  
Very High

Carbon/Carbon composites finds its applications in several high temperature applications in the field of Space, Aviation etc. Designing of components or sub systems with carbon/carbon composites is a challenging task. It requires prediction of elastic properties with a very high accuracy. The prediction can be normally done by analytical, numerical or experimental methods. At the design stage the designers resort to numerical predictions as the experimental methods are not feasible during design stage. Analytical methods are complex and difficult to implement. The designers use numerical methods for prediction of elastic properties using Finite Element Modeling (FEM). The spatial distribution of fibers in matrix has an effect on results of prediction of elastic constants. The generation of random spatial distribution of fibers in representative volume element (RVE) challenging. The present work is aimed at study of effect of spatial distribution of fiber in numerical prediction of elastic properties of unidirectional carbon/carbon composites. MATLAB algorithm is used to generate the spatial distribution of fibers in unidirectional carbon/carbon composites. The RVE elements with various random fiber distributions are modeled using numerical Finite element Model using ABAQUS with EasyPBC plugin. The predicted elastic properties have shown significant variation to uniformly distributed fibers.

Vibration Analysis and Evaluation of the Indoor Spiral Steel Stair

2010 ◽  
Vol 163-167 ◽  
pp. 36-43 ◽  
Author(s):  
Bin Zhou ◽  
Xiao Song Ren ◽  
Xi Lin Lu
Keyword(s):  
Vibration Analysis ◽  
Space Structure ◽  
Vertical Acceleration ◽  
Design Code ◽  
Load Model ◽  
Analysis And Evaluation ◽  
Comfort Evaluation ◽  
Practical Project ◽  
Research Achievement ◽  
Site Test

The spiral steel stair is widespread used as indoor stair for its graceful appearance. For the space structure system of the spiral stair, it is necessary to make vibration analysis and comfort evaluation to the stair. The load model of pedestrian and the analysis condition by walking and running in the process of ascending and descending are presented in this paper. Referring to some design code and research achievement of footbridge and floor, the index of comfort evaluation, which are the natural frequency, the peak vertical acceleration and the weighted root-mean-square (r.m.s) acceleration, are put forward in this paper. Finally, the numerical analysis and the vibration site test of a practical project are made and the results of vibration analysis and comfortability evaluation are presented to demonstrate the suggestion by the authors.

Influence of Pedestrian Number on Vibration Serviceability of Footbridge

2014 ◽  
Vol 1049-1050 ◽  
pp. 378-382
Author(s):  
Ju Bing Zhang ◽  
Shao Xia Zhang ◽  
Ying Zou
Keyword(s):  
Finite Element ◽  
Flow Simulation ◽  
Steel Structure ◽  
Element Model ◽  
Simulation Software ◽  
Force Model ◽  
Social Force ◽  
Vibration Data ◽  
Finite Element Software ◽  
Vibration Serviceability

In recent years, the problem of the human-induced bridge vibration has attracted more and more concerns. In this paper , a steel structure footbridge named Shuang'an East in Beijing was taken as the example to collect the whole bridge vibration data and build the finite element model with the finite element software. In addition, this research changes the limitation of considering the pedestrian load as a whole with a traffic flow simulation software, which is based on social force model, applying to reflect the pedestrians' locations during walking. Comparing the simulation data with the the measured data, the vibration serviceability of footbridge will decrease with the increasing of the number of the pedestrians. The analysis results will provide reference for the dynamic characteristic of similar structures.

A Study on Process-Induced Warpage of Curing Mold of Composite Structures

2009 ◽  
Vol 79-82 ◽  
pp. 1173-1176
Author(s):  
Guang Quan Yue ◽  
Bo Ming Zhang ◽  
Shan Yi Du ◽  
Fu Hong Dai ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Thermal Load ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Coupling Problem ◽  
Dimensional Precision ◽  
Numerical Predictions ◽  
Dimensional Finite Element ◽  
Thermosetting Composite ◽  
Three Dimensional Finite Element

Framed curing mold is subjected to an uneven thermal load, gravity force and the pressures from composite parts and auxiliary tools during autoclave processing of thermosetting composite structures. And those loads induce the warpage of framed-mold. The warpage of framed-mold during autoclave processing influences dimensional precision of composite parts. In the present work, a three-dimensional finite element model for prediction of the warpage of framed-mold during autoclave processing has been developed. This model solved the coupling problem between the deformation and the temperature distribution of framed-mold and allows analysis of all major identified deformation influencing factors. And numerical predictions compare quite well with experimental measurements. A parametric study was performed using FEM program to examine the effect of varying the thickness of framed-mold, the shape and the dimension of mold vents.

scholarly journals Study of Deformation Stability during Semi-Dieless Drawing of Ti-6Al-4V Alloy Wire

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1320
Author(s):  
Kaisong Li ◽  
Zhangke Wang ◽  
Xuefeng Liu
Keyword(s):  
Finite Element ◽  
Heating Temperature ◽  
Element Model ◽  
Drawing Speed ◽  
Dieless Drawing ◽  
Deformation Stability ◽  
Increasing Trend ◽  
Speed Range ◽  
Feeding Speed ◽  
The Finite Element Model

A semi-dieless drawing technology has the advantages of producing a large deformation in a single pass and achieving high-precision dimensions of the finished products. However, instabilities can easily occur in a technique with a large amount of deformation, resulting in its failure. Herein, the deformation behavior of a wire during semi-dieless drawing is studied by finite element simulations. The instability mechanism of the semi-dieless drawing is proposed and validated by experiments. The experiments are conducted under the following conditions: a heating temperature of 950 °C; a distance between the die and heating coil of 20 mm; a feeding speed of 0.25 mm/s; a drawing speed range of 0.38–0.53 mm/s, and a die diameter range of 1.8–2.4 mm. The results show that by increasing the drawing speed or decreasing die diameter, the diameter fluctuation of the dieless drawn wire increases, and the semi-dieless drawing process easily becomes unstable. The diameter of the entering wire shows a fluctuating increasing trend owing to the variation in the drawing speed, which results in the instability during the semi-dieless drawing. The validity of the finite element model is verified by comparing the numerically predicted value and experimentally measured value of the drawn wire diameter.

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