• Wind and Structures
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• v.6 no.3
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• pp.179-196
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• 2003

A long suspension bridge is often located within a unique wind environment, and strong winds at the site seldom attack the bridge at a right angle to its long axis. This paper thus investigates the buffeting response of long suspension bridges to skew winds. The conventional buffeting analysis in the frequency domain is first improved to take into account skew winds based on the quasi-steady theory and the oblique strip theory in conjunction with the finite element method and the pseudo-excitation method. The aerodynamic coefficients and flutter derivatives of the Tsing Ma suspension bridge deck under skew winds, which are required in the improved buffeting analysis, are then measured in a wind tunnel using specially designed test rigs. The field measurement data, which were recorded during Typhoon Sam in 1999 by the Wind And Structural Health Monitoring System (WASHMS) installed on the Tsing Ma Bridge, are analyzed to obtain both wind characteristics and buffeting responses. Finally, the field measured buffeting responses of the Tsing Ma Bridge are compared with those from the computer simulation using the improved method and the aerodynamic coefficients and flutter derivatives measured under skew winds. The comparison is found satisfactory in general.

• Journal of the Korean Institute of Navigation
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• v.13 no.3
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• pp.45-65
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• 1989

Various typhoon data near Yongil Bay, Korea from 1961 to 1985 were collected with some critria and analyzed with the help of the computer. Introducing the pressure profile models and predicting the typhoon wind and wave fields, the 100-year design wave parameters were calculated. Additionally, the wave data at the southeast coast of Korea were statistically analyzed. The deep water wave climate of this bay indicated that Typhoon Brenda, 1985 had wave characteristics of 100-year return period, Typhoon model and storm surge model studies were made for this typhoon. These, including other design parameters, were introduced into the calculation of total design water depth.

• Journal of Navigation and Port Research
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• v.29 no.2
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• pp.151-157
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• 2005

During the period of every summer to early autumn seasons, ships have been wrecked or grounded from effect of a typhoon in the water areas around Korean Peninsula Typhoon Rusa killed more than 100 people in September 2002. Super Typhoon Maemi passed southeast of South Korea in September 12-13, 2003, with a strong gale blowing at a record 60 m/s and caused much ship groundings, collisions and sinkings over 3000 in dockyards, harbors and places of refuge. These are things that could have been prevented had there merely been prior warning. This study outlines the occurrence characteristics of maritime accidents caused by a typhoon in South Korea for the period from 1962 to 2002. The distribution of the accident records is also compared with the trajectories, winds, central pressures of typhoons, passed during the 1990-2003. It is shown that attack frequency of typhoon and number of marine accidents is the highest in August and the marine accidents due to typhoon have a close relation to the distribution of accumulated wind and pressure fields.

• Journal of Environmental Science International
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• v.28 no.4
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• pp.441-454
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• 2019

The present study analyzes the characteristics of 43 typhoons that affected the Korean Peninsula between 2002 and 2015. The analysis was based on 3-second gust measurements, which is the maximum wind speed relevant for typhoon disaster prevention, using a typhoon disaster prevention model. And the distribution and characteristics of the 3-second gusts of four typhoons, RUSA, MAEMI, KOMPASU, and BOLAVEN that caused great damage, were also analyzed. The analysis show that between May and October during which typhoons affected the Korean Peninsula, the month with the highest frequency was August(13 times), followed by July and September with 12 occurrences each. Furthermore, the 3-second gust was strongest at 21.2 m/s in September, followed by 19.6 m/s in August. These results show that the Korean Peninsula was most frequently affected by typhoons in August and September, and the 3-second gusts were also the strongest during these two months. Typhoons MAEMI and KOMPASU showed distribution of strong 3-second gusts in the right area of the typhoon path, whereas typhoons RUSA and BOLAVEN showed strong 3-second gusts over the entire Korean Peninsula. Moreover, 3-second gusts amount of the ratio of 0.7 % in case of RUSA, 0.8 % at MAEMI, 3.3 % at KOMPASU, and 21.8 % at BOLAVEN showed as "very strong", based on the typhoon intensity classification criteria of the Korea Meteorological Administration. Based on the results of this study, a database was built with the frequencies of the monthly typhoons and 3-second gust data for all typhoons that affected the Korean Peninsula, which could be used as the basic data for developing a typhoon disaster prevention system.

• Journal of the korean society of oceanography
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• v.34 no.2
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• pp.73-85
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• 1999

When typhoons passed around the Korea Strait, some observation in this strait carried out by Mizuno et al. (1986) gives us the following oceanographic features; 1) the direction of the observed current was opposite to the northeasterly wind, 2) temperature rapidly increased having a time lag as the depth deepens, after then decreased with oscillation. A primitive equation ocean model that makes use of a sigma-coordinate system and incorporates a typhoon model was used to examine the mechanism to generate these phenomena. The model region covers the East China Sea, the Yellow Sea, and a portion of the East Sea (Japan Sea). The model well reproduces the observed features, especially in temperature field, and clearly manifests how the above observed features happened. From early time when the typhoon was located in low latitude, an alongshore northward current in the west of Kyushu (hereafter the West Kyushu Current) is generated by an alongshore wind in the typhoon. This current flows into the eastern channel, as a coastal jet, regardless to the wind field within the Korea Strait during this period. The above observed phenomena are generated by this current. The model results indicate that when typhoons pass around the Korea Strait, the West Kyushu Current is generated, and oceanographic condition in the strait should be greatly influenced by this current.

• Smart Structures and Systems
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• v.17 no.3
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• pp.491-522
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• 2016

A benchmark problem for modal identification of a cable-stayed bridge was proposed by a research team at Hong Kong Polytechnic University. By taking an instrumented cable-stayed bridge as a test bed, nineteen sets of vibration records with known/unknown excitations were provided to invited researchers. In this paper, the vibration responses of the bridge under a series of excitation conditions are examined to estimate the wind and traffic-induced variations of its dynamic characteristics. Firstly, two output-only experimental modal identification methods are selected. Secondly, the bridge and its monitoring system are described and the nineteen sets of vibration records are analyzed in time-domain and frequency-domain. Excitations sources of blind datasets are predicted based on the analysis of excitation conditions of known datasets. Thirdly, modal parameters are extracted by using the two selected output-only modal identification methods. The identified modal parameters are examined with respect to at least two different conditions such as traffic- and typhoon-induced loadings. Finally, the typhoon-induced effects on dynamic characteristics of the bridge are estimated by analyzing the relationship between the wind velocity and the modal parameters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.107-112
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• 2018

One-dimensional numerical model is implemented to investigate temperature variations in the mixed layer depth (MLD) with the passage of typhoons. In the model, we assume a non-divergent, infinite ocean and consider wind effects only, excluding isostatic effects (inverse barometric effects) and upwelling with vertical movement of the water column. Numerical experiments investigate the effects of typhoon tracks on temperature variations, including their dependence on vertical resolutions in the MLD and these results are compared with those in a three-dimensional primitive equation model (POM). The model reproduces features of the observed temperature variations in the MLD fairly well, and implies that wind effects, rather than isostatic effects, play a predominant role in temporal and spatial temperature variations in the MLD. After the passage of typhoons, however, the model does not reproduce well the temperature variations observed in the MLD, because a limitation of the model is its inability to reproduce events such as cyclonic eddy formation (Hong et al., 2011; Masuda and Hong, 2011). The model also shows well the so called 'rightward bias' (Price, 1981) of sea surface cooling which is the most predominant in the right hand side of typhoon's track.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.439-446
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• 1999

This research was performed to study the actual behavior of 1-2W type pipe greenhouse under the influence of typhoon by measuring the vairous strains instructural materials. These results can eventually be utilized in the desgin criteria as well as in the modification of conventional equaltion for calcu more realistic wind loads. Tehfirst data under the influence of Typhoon Olga arrived in Jinju on Aug. 1999. Were obtained by strain gage with 10 sensor points. According to the data obtained, the typical variation ofstrain depending on wind patter could be observed. The strains in structural frame were fluctuated very sensitively depending on the direction and magnitude of wind velocity. But some of the data were lost or missed by system's failure. A kind of inherent vibration pattern of greenhouse pipe frame was observed from the plotted data, but this phenomenon is not so clear as to be separated from the overall fluctuation so far. This experimental research is expected to be continued as a long term project to measure and analyze the strain pattern of structural frame depending on the various locations and section characteristics by wasy of adopting more efficientg instrument with sufficient number of measuring points and accuracy.

• Wind and Structures
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• v.26 no.1
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• pp.11-24
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• 2018

Full-scale measurements of wind action on the open roof structure of the WuXi grand theater, which is composed of eight large-span free-form leaf-shaped space trusses with the largest span of 76.79 m, were conducted during the passage of Typhoons HaiKui and SuLi. The wind pressure field data were continuously and simultaneously monitored using a wind pressure monitoring system installed on the roof structure during the typhoons. A detailed analysis of the field data was performed to investigate the characteristics of the fluctuating wind pressure on the open roof, such as the wind pressure spectrum, spatial correlation coefficients, peak wind pressures and non-Gaussian wind pressure characteristics, under typhoon conditions. Three classical methods were used to calculate the peak factors of the wind pressure on the open roof, and the suggested design method and peak factors were given. The non-Gaussianity of the wind pressure was discussed in terms of the third and fourth statistical moments of the measured wind pressure, and the corresponding indication of the non-Gaussianity on the open roof was proposed. The result shows that there were large pulses in the time-histories of the measured wind pressure on Roof A2 in the field. The spatial correlation of the wind pressures on roof A2 between the upper surface and lower surface is very weak. When the skewness is larger than 0.3 and the kurtosis is larger than 3.7, the wind pressure time series on roof A2 can be taken as a non-Gaussian distribution, and the other series can be taken as a Gaussian distribution.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.489-492
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• 2006

In this study we collected and analyzed cases where typhoons damaged coastal structures in Korea in the past 6 years, and hydraulic model tests were conducted in 2D flume. 2 areas where damage was concentrated were selected from ports that had suffered damage. The selected area was Kyungsang-namdo, where there are a total of 26 national ports. Damage to these two areas was organized by wind direction of the typhoons and the direction of the entrance of the port, and destruction patterns were analyzed. 2D hydraulic model tests were conducted of Deabyeun port, one of the damaged areas. Results were as follows: 1. As a result of survey, ports that had entrances that were open to winddirection of typhoon (Anti-clockwise direction) tended to be damaged mare, whereas ports that blocked by island and ports that were not open to wind direction of typhoon were not damaged. 2. As a result of the tests, there was damage that occurred when using the section of designed section, whereas there was no damage when the TTP weight was increased.