• Journal of Wind Energy
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• v.13 no.4
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• pp.80-89
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• 2022

In this paper, a study was conducted to evaluate the safety of pitch reducers for 8 MW class wind turbines. The housing and carrier of the pitch reducer were subjected to structural analysis for the ultimate load by load duration distribution (LDD). As a result of the finite element analysis of the housing parts, the part with the highest stress was the output housing, and the equivalent stress was 522.4 MPa and the safety factor was 1.14. As a result of finite analysis of the carrier, the highest stress occurred at 80.5 MPa in the first carrier, and the safety factor was 10.3. In addition, extreme strength and life analysis by LDD load were performed for gears and bearings included in each stage. The strength analysis of the planetary gear train was conducted based on ISO 6336, and the stability evaluation of the bearings through life analysis based on ISO 281 found all to be safe.

• Wind and Structures
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• v.17 no.2
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• pp.227-244
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• 2013

Non-stationary extreme winds such as thunderstorm downbursts are responsible for many structural damages. This research presents a time domain approach for estimating along-wind load effects on tall buildings using multiple wind speed time history samples, which are simulated from evolutionary power spectra density (EPSD) functions of non-stationary wind fluctuations using the method developed by the authors' earlier research. The influence of transient wind loads on various responses including time-varying mean, root-mean-square value and peak factor is also studied. Furthermore, a simplified model is proposed to describe the non-stationary wind fluctuation as a uniformly modulated process with a modulation function following the time-varying mean. Finally, the probabilistic extreme response and peak factor are quantified based on the up-crossing theory of non-stationary process. As compared to the time domain response analysis using limited samples of wind record, usually one sample, the analysis using multiple samples presented in this study will provide more statistical information of responses. The time domain simulation also facilitates consideration of nonlinearities of structural and wind load characteristics over previous frequency domain analysis.

• Wind and Structures
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• v.22 no.1
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• pp.65-87
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• 2016

The wind velocity profile over the height of a structure in high intensity wind (HIW) events, such as downbursts, differs from that associated with atmospheric boundary layer (ABL) winds. Current design codes for lattice transmission structures contain only limited advice on the treatment of HIW effects, and structural design is carried out using wind load profiles and response factors derived for ABL winds. The present study assesses the load-deformation curve (capacity curve) of a transmission tower under modeled downburst wind loading, and compares it with that obtained for an ABL wind loading profile. The analysis considers nonlinear inelastic response under simulated downburst wind fields. The capacity curve is represented using the relationship between the base shear and the maximum tip displacement. The results indicate that the capacity curve remains relatively consistent between different downburst scenarios and an ABL loading profile. The use of the capacity curve avoids the difficulty associated with defining a reference wind speed and corresponding wind profile that are adequate and applicable for downburst and ABL winds, thereby allowing a direct comparison of response under synoptic and downburst events. Uncertainty propagation analysis is carried out to evaluate the tower capacity by considering the uncertainty in material properties and geometric variables. The results indicated the coefficient of variation of the tower capacity is small compared to those associated with extreme wind speeds.

• Wind and Structures
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• v.31 no.4
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• pp.299-309
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• 2020

In this study, wind data such as speeds, loads and potential of Muğla which is located in the southwest of Turkey were statistically analyzed. The wind data which consists of hourly wind speed between 2010 and 2013 years, was measured at the 10-meters height in four different ground stations (Datça, Fethiye, Marmaris, Köyceğiz). These stations are operated by The Turkish State Meteorological Service (T.S.M.S). Furthermore, wind data was analyzed by using Log-Normal and Gamma distributions, since these distributions fit better than Weibull, Normal, Exponential and Logistic distributions. Root Mean Squared Error (RMSE) and the coefficients of the goodness of fit (R²) were also determined by using statistical analysis. According to the results, extreme wind speed in the research area was 33 m/s at the Datça station. The effective wind load at this speed is 0.68 kN/㎡. The highest mean power densities for Datça, Fethiye, Marmaris and Köyceğiz were found to be 46.2, 1.6, 6.5 and 2.2 W/㎡, respectively. Also, although Log-normal distribution exhibited a good performance i.e., lower AD (Anderson - Darling statistic (AD) values) values, Gamma distribution was found more suitable in the estimation of wind speed and power of the region.

• Wind and Structures
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• v.38 no.6
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• pp.477-492
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• 2024

This study presents a comprehensive investigation of wind load characteristics and wind-induced responses associated with different wind incidence angles and terrains of the 1000kV UHV substation frame. High-frequency force balance (HFFB) force measurement wind tunnel tests are conducted on the overall and segment models to characterize wind loads characteristics such as the aerodynamic force coefficients and the shape factors. The most unfavorable wind incidence angles and terrains for aerodynamic characteristics are obtained. A finite element model of the substation frame is built to determine the wind-induced response characters based on the aerodynamic force coefficients and bottom forces of the segment models. The mean and root mean square (RMS) values of displacement responses at different heights of the frame structure are compared and analyzed. The influence of wind incidence angle and terrains on wind-induced responses is also examined. The displacement responses in terms of the crest factor method are subsequently transformed into dynamic response factors. The recommended values of dynamic response factors at four typical heights have been proposed to provide a reference for the wind resistance design of such structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.155-162
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• 2001

In this study a structure with viscoelastic and viscous dampers with identical damping coefficient subjected to stationary seismic and wind load were analyzed in time and frequency-domain to compare motion control capability of viscous and viscoelastic dampers. The dampers were placed based on story drift and acceleration obtained from RMS responses. According to the analysis results, the motion control capability of viscous dampers turned out to be superior to that of the viscoelastic dampers for the case of seismic load. On the contrary, in case of wind load, the viscoelastic dampers were more effective in the mitigation of dynamic responses. However, it was also found that the differences were in a narrow margin.

• Structural Engineering and Mechanics
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• v.48 no.4
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• pp.467-477
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• 2013

Municipalities in the United Arab Emirates approve reinforced concrete design of building structures to follow either the ACI 318 or the BS 8110 code. Since the requirements of these codes are different from each, there is a need to compare the structural demand in the two codes. The main objective of this study is to compare the design requirements of the ACI 318 code with the BS 8110 code for the flexural, shear and axial compression limit states. The load factors and load combinations in the two codes are also compared. To do so, a large number of cross-sections with different geometries, material properties, and reinforcement ratios are analyzed following the procedures in the two codes. The relevant factored load combinations in the two codes are also investigated for a wide range of live-to-dead load ratios and for various wind-to-dead load ratios. The study showed that the differences between the design capacities in the ACI 318 and BS 8110 codes are minor for flexure, moderate for axial compression, and major for shear. Furthermore, the factored load combinations for dead load, live load and wind in the two codes yield minor-to-moderate differences, depending on the live-to-dead load ratio and intensity of wind.

• Wind and Structures
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• v.25 no.2
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• pp.101-129
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• 2017

Local transient extreme wind loads caused by group tower-related interference are among the major reasons that lead to wind-induced damage of super-large cooling towers. Four-tower arrangements are the most commonly seen patterns for super-large cooling towers. We considered five typical four-tower arrangements in engineering practice, namely, single row, rectangular, rhombic, L-shaped, and oblique L-shaped. Wind tunnel tests for rigid body were performed to determine the influence of different arrangements on static and dynamic wind loads and extreme interference effect. The most unfavorable working conditions (i.e., the largest overall wind loads) were determined based on the overall aerodynamic coefficient under different four-tower arrangements. Then we calculated the one-, two- and three-dimensional aerodynamic loads under different four-tower arrangements. Statistical analyses were performed on the wind pressure signals in the amplitude and time domains under the most unfavorable working conditions. On this basis, the non-Gaussian distribution characteristics of aerodynamic loads on the surface of the cooling towers under different four-tower arrangements were analyzed. We applied the Sadek-Simiu procedure to the calculation of two- and three-dimensional aerodynamic loads in the cooling towers under the four-tower arrangements, and the extreme wind load distribution patterns under the most unfavorable working conditions in each arrangement were compared. Finally, we proposed a uniform equation for fitting the extreme wind loads under the four-tower arrangements; the accuracy and reliability of the equation were verified. Our research findings will contribute to the optimization of the four-tower arrangements and the determination of extreme wind loads of super-large cooling towers.

• Journal of Bio-Environment Control
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• v.7 no.3
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• pp.181-190
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• 1998

An elastic analysis under wind load was performed for the double layered plastic greenhouse model developed particularly for minimizing damages under typhoons at Cheju Citrus Research institute in Seagipo city. General EVA film was used for the inner covering and the developed special film which would break the wind pressure down was used for the outer covering. The wind tunnel test showed this special film reduced the wind speed up to 86 to 98% under well controlled situation. Based on the elastic analysis performed in the study, the behavior of the greenhouse was changed significantly due to the boundary conditions. Not like other researchers before we applied dead load of the concrete support to the ground pipe and fixed support boundary conditions at the 4 corner pipes. The analysis shows that the greenhouse was lifted and pulled the pipe out of the ground due to the sucking wind pressure. The behavior of the greenhouse was quite similar to that one real greenhouse failure. Therefore, not only we need to find the realistic boundary conditions for the supports, but also need to find how to rest the pipe supports on the ground without economic loss.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.241-246
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• 2005

This study is carried out to analyze the stability of a container crane in according to the change of a wind direction and a machinery house location when a wind load of a wind velocity, 75m/s was applied on the state stowing a container crane by a heavy wind A design wind load applied to this study was calculated in observance of 'Load Criteria of Building Structure'. And we analyzed the reactions of each supporting points according to appling a wind direction to an interval of $15^{\circ}$ in $0^{\circ}\~180^{\circ}$ and the structure stability of a container crane according to changing a machinery house location occupying $15\%$ of a container crane weight. From a results of this study, we presented a design criteria of an overturning disturbance equipment, tie-down.