• Wind and Structures
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• v.36 no.2
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• pp.121-131
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• 2023

Aiming at the problem that fatigue characteristics of metal roof rely on local physical tests and lacks the cyclic load sequence matching with regional climate, this paper proposed a method of constructing the fatigue load spectrum based on integration of wind load model, measured data of long-span metal roof and climate statistical data. According to the turbulence characteristics of wind, the wind load model is established from the aspects of turbulence intensity, power spectral density and wind pressure coefficient. Considering the influence of roof configuration on wind pressure distribution, the parameters are modified through fusing the measured data with least squares method to approximate the actual wind pressure load of the roof system. Furthermore, with regards to the wind climate characteristics of building location, Weibull model is adopted to analyze the regional meteorological data to obtain the probability density distribution of wind velocity used for calculating wind load, so as to establish the cyclic wind load sequence with the attributes of regional climate and building configuration. Finally, taking a workshop's metal roof as an example, the wind load spectrum is constructed according to this method, and the fatigue simulation and residual life prediction are implemented based on the experimental data. The forecasting result is lightly higher than the design standards, consistent with general principles of its conservative safety design scale, which shows that the presented method is validated for the fatigue characteristics study and health assessment of metal roof.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.184-189
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• 2008

In this study, an artificial wheel load generation method is proposed to assist practical engineers performing dynamic analysis with simple procedure. To generate an artificial wheel loads from running vehicle, PSD(Power Spectrum Density) profiles of actual wheel load were sampled in terms of various road roughnesses. A detailed truck and bridge models were used for sampling actual wheel load to represent the real motion of moving vehicle. These wheel load profiles were simplified for the artificial wheel load. The simplification of actual wheel load profiles was performed by regression analysis. The result showed that the artificial wheel load well represents the real profiles of wheel load.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.29-37
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• 2006

The primary objective of this study is to characterize traffic axle loadings that consider Korea specific traffic conditions for developing mechanistic-based pavement design method as a part of Korea Pavement Research Program(KPRP). Although the concept of equivalent single axle load(ESAL) has been generally used since the 1960s for the pavement design, the mechanistic-based pavement design procedure requires more accurate axle loading data on the specific pavement. In this study, axle loading data were collected according to vehicle type and highway functional classification. Axle-load spectrum was then standardized by cumulative density function(cdf), because the axle load spectrum could vary from the observed site, truck traffic volume, and truck type, Finally, this study presented the procedure and S-shaped exponential models for characterizing axle load spectra according to vehicle type and highway functional classification.

• New & Renewable Energy
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• v.3 no.4
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• pp.114-122
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• 2007

This paper addresses the measurement of structural loads on the Unison U50 wind turbine. The load measurement are carried out to determine the actual loads acting on a wind turbine. This is needed not only the certification process but also improving the technical development for prototype wind turbine. The measurement system is consists of measuring load, operating quantities and meteorological signal. All data that occur during the operating of a WT are stored the data acquisition system automatically. With using the measured data, load spectrum and equivalent load are evaluated according to IEC61400-13 "Measurement of mechanical loads".

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.341-344
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• 2007

This paper addresses the measurement of structural loads on the Unison U50 wind turbine. The load measurement are carried out to determine the actual loads acting on a wind turbine. This is needed not only the certification process but also improving the technical development for prototype wind turbine. The measurement system is consists of measuring load, operating quantities and meteorological signal. All data that occur during the operating of a WT are stored the data acquisition system automatically. With using the measured data, load spectrum and equivalent load are evaluated according to IEC61400-13 "Measurement of mechanical loads".

• Journal of Aerospace System Engineering
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• v.1 no.2
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• pp.27-36
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• 2007

The Damage Tolerant Design is developed to help alleviate structural failure and cracking problems in aerospace structures. Recently, the Damage Tolerant Design is required and recommended for most of aircraft design. In this paper, the damage tolerant design is applied to tilt rotor UAV. First of all, the fatigue load spectrum for the tilt rotor UAV is developed and fatigue analysis is performed for the flaperon joint which has FCL (fatigue critical location). Tilt rotor UAV has two modes: helicopter mode when UAV is taking off and landing; fixed wing mode when the tilt rotor UAV is cruising. To make fatigue load spectrum, FELIX is used for helicopter mode. TWIST is used for fixed wing mode. Fatigue analysis of flaperon joint is performed using fatigue load spectrum. E-N curve approach is used for picking crack initiation point. The LEFM(Linear Elastic Fracture Method) is considered for analyzing crack growth or propagation. Finally, including the crack initiation and propagation, the fatigue life is evaluated. Therefore the Damage Tolerant Design can be done.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.9-18
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• 2019

This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.5
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• pp.67-73
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• 2003

The present seismic analysis of Road-Bridge Design Standard is on a basis of load-based analysis which lets structures have the strength over load. In this study, the capacity spectrum method, a kind of displacement based method, which is evaluated by displacement of structure, is presented as an alternative to the analysis method based on load. Seismic capacity is performed about the existing reinforced concrete pier which has already secured seismic design by capacity spectrum method. As a result. capacity spectrum method could realistically evaluate the non-elastic behavior of structures easily and quickly and the displacement of structures for variable ground motion level. And it could efficiently apply to an evaluation of seismic capacity about the existing structure and a verification of design for capacity target of the new structure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.387-392
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• 2007

The loss of strength in an aircraft structure as a result of cyclic stress over a period of life time is an important phenomenon for aircraft analysis. Load/stress spectrum can be constructed from the occurrence frequency based on the load/stress histories during a service lifetime. In this paper, three types of fatigue spectrum was compared. The rainflow counting method was applied to concentrate the stress spectrum obtained from the flight loads recorder(FLDR). A fatigue analysis for different stress spectrum was performed by using LUSAS computer application.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.163-171
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• 2006

To evaluate inelastic seismic responses of multi-span-bridge, the equivalent single-degree-of-freedom (ESDOF) methods and the lateral load distributions are applied to the capacity spectrum method(CSM). From the pushover analysis results using the four ESDOF methods and the six types lateral load distributions, the ESDOF method more than lateral load distribution is found to have an important influence upon the pushover analysis. The effects of the higher mode on the bridge seismic behaviors are also increased as the number of pier increase. Therefore, it can be concluded that lateral load distributions and ESDOF methods for reflection of higher mode effects should be considered in the seismic analysis of the bridge structural.