Risk Assessment of Vehicle on a Bridge for Strong Wind based on Wind-tunnel Experiment

2019 ◽  
Author(s):  
Se-Jin Kim ◽  
Ho-Kyung Kim
Keyword(s):  
Risk Assessment ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Risk Index ◽  
Distribution Functions ◽  
Assessment Procedure ◽  
Strong Wind ◽  
Critical Wind Speed ◽  
Traffic Lane ◽  
Wind Distribution

<p>Risk assessment method of vehicle for strong wind on a bridge was developed with consideration of girder shape and wind environment. The method is composed of three steps. In first step, wind tunnel test is performed to estimate aerodynamic coefficients of a vehicle. Coefficients are estimated for every traffic lane on the bridge with consideration of various wind direction. Based on the results, critical wind speed curves of vehicles are calculated through vehicle dynamics analysis. Next step is wind environmental analysis. Utilizing long-term wind data obtained from nearby weather station, wind distribution functions are estimated. As a final step, number of days for traffic control, risk index in this study, is calculated using critical wind speed curves and wind distribution functions. The risk index is obtained not only for main span of the bridge, but also for all side spans or approaches. As a case study, Gwang-an bridge, one of long span bridge in Korea, was evaluated using developed assessment procedure. Risk index was calculated for all sections on the bridge, and mitigation measure was also discussed to ensure the vehicle safety.</p>

scholarly journals Effects of central stabilizing barriers on flutter performances of a suspension bridge with a truss-stiffened deck under skew winds

2018 ◽  
Vol 22 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Ledong Zhu ◽  
Xiao Tan ◽  
Zhenshan Guo ◽  
Quanshun Ding
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Inclination Angle ◽  
Suspension Bridge ◽  
Control Measures ◽  
Wind Effect ◽  
Wind Condition ◽  
Wind Tunnel Tests ◽  
Critical Wind Speed ◽  
Bridge Span

To improve the flutter performance of a suspension bridge with a 1088-m-span truss-stiffened deck, the aerodynamic measures of upper and lower central stabilizing barriers were investigated at first via wind tunnel tests of sectional model under the normal wind condition. The yaw wind effect on the flutter performance of the bridge with the above aerodynamic measures was then examined via a series of wind tunnel tests of oblique sectional models. The test results show that the effect of the lower central stabilizing barrier on the flutter critical wind speed is remarkably different from that of the upper central stabilizing barrier for both the normal and skew wind cases. The inclination angle +3° is the most unfavorable inclination angle to the flutter performance of the truss-stiffened suspension bridge no matter whether the aerodynamic control measures are adopted or not. Furthermore, for most cases, the lowest flutter critical wind speed occurs when the incident wind deviates from the normal direction of the bridge span by a small yaw angle between 5° and 10°.

Research on the Aerodynamic Measures Impact on Flutter Stability of Steel Truss Suspension Bridge

2013 ◽  
Vol 791-793 ◽  
pp. 378-381
Author(s):  
Hua Bai ◽  
Sen Hua Huang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Suspension Bridge ◽  
Wind Tunnel Experiment ◽  
Attack Angle ◽  
Torsional Stiffness ◽  
Critical Wind Speed ◽  
Guide Plate ◽  
Steel Truss ◽  
Better Than

The flutter stability of the steel truss suspension bridge is hard to reach the requirement of the wind resisting stability when lacks the torsional stiffness. This paper discusses the influence of aerodynamic measure combination, such as central stabilizer, air director enclosed anti-collision bar and so on, towards the flutter stability of steel truss through the wind tunnel experiment of the bridge of Liu Jia gorge. The result shows: the effect of using both the upper and lower stabilized plate is better than separated used it. when sectionalized dispose upper stabilized plate, the flutter critical wind speed of attack angle will decrease rapidly. Outlaying the horizontal guide plate is better than internally installed; The flutter stability of different attack angle tend to be balanced by widening the horizontal guide plate. The anti-collision bar can be functionalized as the central stabilizer by heightening and enclosing, and effectively increase the critical wind speed of different attack angles of the high truss suspension bridge.

scholarly journals Analysis of wind speed characteristics using different distribution models in Medan City, Indonesia

2021 ◽  
Vol 12 (2) ◽  
pp. 1102
Author(s):  
Suwarno Suwarno ◽  
Ismail Yusuf ◽  
M. Irwanto ◽  
Ayong Hiendro
Keyword(s):  
Wind Speed ◽  
Density Function ◽  
Weibull Model ◽  
Exponential Model ◽  
Distribution Functions ◽  
Cumulative Probability ◽  
Distribution Models ◽  
Shape Factors ◽  
Wind Characteristics ◽  
Wind Distribution

<span lang="EN-CA">Estimating wind speed characteristics plays an essential role in designing a wind power plant at a selected location. In this study, the Weibull, gamma, and exponential distribution models were proposed to estimate and analyze the wind speed parameters and distribution functions. Real measured data were collected from Medan City, Indonesia. The scale and shape factors of wind distribution for three years data were calculated. The observed cumulative probability of the three models was compared to predicted wind characteristics. The probability density function (PDF) and the cumulative density function (CDF) of wind speed were also analyzed. The results showed that the Weibull model was the best model to determine PDF, while the exponential model was the best model to determine CDF for the Medan City wind site.</span>

scholarly journals Development of saltation layer of drifting snow

2004 ◽  
Vol 38 ◽  
pp. 35-38 ◽  
Author(s):  
Takeshi Sato ◽  
Kenji Kosugi ◽  
Atsushi Sato
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Snow Cover ◽  
Friction Velocity ◽  
Transport Rate ◽  
Strong Wind ◽  
Wind Tunnel Experiments ◽  
Drifting Snow ◽  
Starting Point

AbstractThe saltation length of aeolian snow particles and a new parameter, the ejection factor, which expresses the degree of erosion due to drifting snow, were obtained as functions of friction velocity by means of wind-tunnel experiments for semi-hard snow cover. The saturated-snowdrift transport rate was also obtained experimentally as a function of friction velocity. Based on these characteristics and the parameter, the development of the saltation layer of drifting snow along the fetch was simulated under various conditions such as snow hardness, wind speed and snowfall intensity. The main results are as follows. The developing distance denoting the distance required for the saltation layer to attain saturation, X sat, is determined by saltation length, ejection factor and saturated-snowdrift transport rate, all of which depend on wind speed. It is also affected by the magnitude of snowdrift transport rate at the starting point and by the intensity of snowfall if it exists. The dependence of Xsat on wind speed is not simple in the case of semi-hard snow cover: Xsat increases with wind speed under weak to moderate wind conditions and then decreases under moderate to strong wind conditions. It is sensitive to snow hardness: it is about one order longer on hard snow cover than on semi-hard snow cover. Snowfall reduces not only the value of Xsat but also its dependence on snow hardness.

scholarly journals Flutter Performance of the Emergency Bridge with New-Type Cable-Girder

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Lei Yang ◽  
Fei Shao ◽  
Qian Xu ◽  
Ke-bin Jiang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Analysis Program ◽  
Aerodynamic Optimization ◽  
Wind Resistance ◽  
Optimal Scheme ◽  
Critical Wind Speed ◽  
Flutter Analysis ◽  
New Type ◽  
Optimization Schemes

Based on the proposed emergency bridge scheme, the flutter performance of the emergency bridge with the new-type cable-girder has been investigated through wind tunnel tests and numerical simulation analyses. Four aerodynamic optimization schemes have been developed in consideration of structure characteristics of the emergency bridge. The flutter performances of the aerodynamic optimization schemes have been investigated. The flutter derivatives of four aerodynamic optimization schemes have been analyzed. According to the results, the optimal scheme has been determined. Based on flutter theory of bridge, the differential equations of flutter of the emergency bridge with new-type cable-girder have been established. Iterative method has been used for solving the differential equations. The flutter analysis program has been compiled using the APDL language in ANSYS, and the bridge flutter critical wind speed of the optimal scheme has been determined by the program. The flutter analysis program has also been used to determine the bridge flutter critical wind speed of different wind-resistance cable schemes. The results indicate that the bridge flutter critical wind speed of the original emergency bridge scheme is lower than the flutter checking wind speed. The aerodynamic combined measurements of central-slotted and wind fairing are the optimal scheme, with the safety coefficients larger than 1.2 at the wind attack angles of −3°, 0°, and +3°. The bridge flutter critical wind speed of the optimal scheme has been determined using the flutter analysis program, and the numerical results agree well with the wind tunnel test results. The wind-resistance cable scheme of 90° is the optimal wind cable scheme, and the bridge flutter critical wind speed increased 31.4%. However, in consideration of the convenience in construction and the effectiveness in erection, the scheme of wind-resistance cable in the horizontal direction has been selected to be used in the emergency bridge with new-type cable-girder.

scholarly journals Study on distribution characteristics of wind speed field in the sea area of Ly Son island of Quang Ngai province

2021 ◽  
Vol 20 (4A) ◽  
pp. 11-20
Author(s):  
Tran Van Chung ◽  
Ngo Manh Tien ◽  
Nguyen Van Long
Keyword(s):  
Wind Speed ◽  
Extreme Value Distribution ◽  
Distribution Functions ◽  
Distribution Characteristics ◽  
Characteristic Parameters ◽  
Distribution Law ◽  
Probability Distribution Functions ◽  
Data Source ◽  
Wind Distribution ◽  
Sea Area

On the basis of the data source of the 10 m wind field above the sea with the hourly frequency and during the period of 41 years (1979–2019) by the NCEP CFRS, we used the probability distribution functions to study the distribution law of wind speed in the waters of Ly Son island. Specifically, four distribution functions (normal distribution, gamma distribution, Weibull distribution and extreme value distribution) were used to estimate the characteristic parameters of the shape and proportion of the wind distribution in the waters of Ly Son island.

Development of Probabilistic Risk Assessment Methodology of Decay Heat Removal Function Against Combination Hazards of Strong Wind and Rainfall for Sodium-Cooled Fast Reactors

2017 ◽  
Author(s):  
Hidemasa Yamano ◽  
Hiroyuki Nishino ◽  
Kenichi Kurisaka
Keyword(s):  
Risk Assessment ◽  
Wind Speed ◽  
Cooling System ◽  
Heat Removal ◽  
Strong Wind ◽  
Event Sequence ◽  
Rainfall Duration ◽  
Decay Heat ◽  
Hourly Rainfall ◽  
Air Cooler

This paper describes probabilistic risk assessment (PRA) methodology development against combination hazard of strong wind and rainfall. In this combination hazard PRA, a hazard curve has been evaluated in terms of maximum instantaneous wind speed, hourly rainfall, and rainfall duration. A scenario analysis provided event sequences resulted from the combination hazard of strong wind and rainfall. The event sequence was characterized by the function loss of auxiliary cooling system, of which heat transfer tubes could crack due to cycle fatigue by cyclic contact of rain droplets. This situation could occur if rain droplets ingress into air cooler occurs after the air cooler roof failure due to strong-wind-generated missile impact. This event sequence was incorporated into an event tree which addressed component failure by the combination hazard. Finally, a core damage frequency has been estimated the order of 10−7/year in total by multiplying discrete hazard frequencies by conditional decay heat removal failure probabilities. A dominant sequence is the failure of the auxiliary cooling system by the missile impact after the failure of external fuel tank by the missile impact. A dominant hazard is the maximum instantaneous wind speed of 40–60 m/s, the hourly rainfall of 20–40 mm/h, and the rainfall duration of 0–10 h.

scholarly journals Comparative evaluation of concrete sand-control fences used for railway protection in strong wind areas

2021 ◽  
Author(s):  
Long Shi ◽  
Dongyuan Wang ◽  
Kai Cui ◽  
Chunxiao Xue
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Comparative Evaluation ◽  
Fine Particles ◽  
Field Monitoring ◽  
Strong Wind ◽  
Aeolian Sand ◽  
Speed Reduction ◽  
Concrete Plate ◽  
Sand Control

AbstractConcrete-plate fences have been widely adopted for windblown sand control and mitigation along railways. However, the inclination angles of inserting the concrete plate with respect to the vertical direction, i.e., straight or obliquely inserted concrete plates (SIP or OIP), significantly influence the efficiency of sand-control. This study performs a comparative evaluation of the SIP and OIP sand-control fences using wind tunnel testing and field monitoring data collected from the Lanzhou–Wulumuqi High-Speed Railway Project. The results show that the fence’s ability to reduce the wind speed and the sand-retaining efficiency gradually weakens with the increasing wind speed. Compared with the SIP fence, the OIP fence has a better wind speed reduction capability, stronger ability to capture fine particles below the top of the fence; it is more efficient for sand-retaining and induces stronger eddy intensity. Generally, the wind tunnel test and field monitoring results are consistent, whereas wind tunnel tests incline to overestimate wind speed reduction and sand-control efficiency. The study also finds that the aeolian sand accumulated around the fence can weaken the protection efficiency, and hence cleaning the aeolian sand accumulated around the fence should be done periodically to ensure the designed functions.

scholarly journals Pedestrian Wind Distribution Within an Urban University City Campus using Wind Tunnel Test

2019 ◽  
Vol 8 (3S3) ◽  
pp. 373-382 ◽  
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Tall Buildings ◽  
Storm Event ◽  
Strong Wind ◽  
Wind Speeds ◽  
Urban City ◽  
Wind Events ◽  
Wind Distribution ◽  
The Impact

There is a necessity to further explore the pedestrian wind studies in Malaysia as in concerning the impact and risk of hazard wind towards community due to the occurrence of strong wind events. The gradually increase of high-rise buildings in an urban city might lead to artificial strong wind, causing wind discomfort or infrastructure damages, In this study, the research framework is demonstrated and the wind distribution within Universiti Teknologi Malaysia Kuala Lumpur (UTMKL) city campus is revealed by conducting wind tunnel test. The results showed that the high wind speeds are spotted near high buildings (MJIIT, Menara Razak, and Residensi Tower of UTMKL) where U(z)/U(zref) ranging from 0.60-0.90. Factors that are causing the wind amplification near tall buildings are downdraft wind at windward of building, wakes at corners, and leeward of building, as well as the venturi effect occurred between two tall buildings. The layout of the buildings also shall be one of the factors that affecting the wind distribution, as there is a case where a group of buildings served as a shelter and refrained the wind to flow through some areas. This preliminary result is also aligned with the storm event that happened. Thus, for the sake of the safety and comfort of the pedestrians, incorporating the wind tunnel data in the future master planning in this city campus should be considered to reduce the wind nuisance issues

Methods of risk assessment in forecasting the consequences of accidents at pipeline transport facilities

2020 ◽  
Vol 10 (6) ◽  
pp. 663-673
Author(s):  
Vladislav N. Slepnev ◽  
◽  
Alexander F. Maksimenko ◽  
Elena V. Glebova ◽  
Alla Т. Volokhina ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Evaluation Method ◽  
Assessment Procedure ◽  
Expert Evaluation ◽  
Main Pipeline ◽  
Pipeline Transport ◽  
Forecasting Accuracy ◽  
Distribution Of Resources ◽  
Expert Evaluation Method

The choice of risk assessment procedure is one of the essential stages of efficient structuring of processes on prevention, localization and elimination of the consequences of accidents at main pipeline transport facilities. The authors analyzed themed publications and regulatory documents, governing procedures of risk assessment and forecasting of the consequences of possible accidents, and defined main problems in this area. Procedure for the risk assessment of accidents at main pipeline facilities was developed, the basis of which is the expert evaluation method. The procedure includes the determination of the main criteria for the assessment the probability of accident initiation and development and the evaluation of the severity of its consequences, an expert evaluation of criteria significance, their classification, and creation of a rating for hazardous pipeline sections. The application of the procedure application allows to specify the list of facilities that require high priority forecasting of accidents consequences, thus to optimize the distribution of resources and the overall increase of efficiency in planning while defining forces and special technical devices, necessary for containment and rectification of emergencies. Expert evaluation method application allows considering the specifics of certain enterprises, their technical and technological peculiarities, thereby increasing forecasting accuracy.

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