• Architectural research
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• v.3 no.1
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• pp.53-60
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• 2001

The proposed building upgrading technique employs prestressing cables to function as bracing to improve the seismic performance during future events. A four-story reinforced concrete moment resisting frame damaged from an ultimate limit state earthquake is assessed and upgraded using the proposed technique. Both existing and upgraded buildings are evaluated in regard of seismic performance parameters performing static lateral load to collapse analysis and dynamic nonlinear time history analysis as well. To obtain realistic comparison of seismic performance between existing and upgraded frames, each frame is subjected to its critical ground motion that has strength demand exceeding the building strength supply. Furthermore, reliability of static lateral load to collapse analysis as a substitute to time history analysis is evaluated. The results reveal that the proposed upgrading technique improves the stiffness distribution compared to the ideal distribution that gives equal inter-story drift. As a result, the upgraded building retains more stories that contribute to energy dissipation. The overall behavior of upgraded building beyond yield is also enhanced due to the gradual change of building stiffness as the lateral load increases.

• Journal of Industrial Technology
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• v.19
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• pp.313-320
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• 1999

Steel railway bridge gets vibration from moving load ; additionally, this kind of moving load is going to be a sufficient reason, which causes fatigue damage to steel railway bridge. Fatigue damage and stress curve were raised by moving load depends on span length in steel railway bridge. In other words, stress curve appears index regarding every axial load in short span, but self weight lets stress curve's change decrease in proportion to increasing span length. Thereby, we have studied that how the steel railway bridge appear fatigue damage in proportion to span length of steel railway bridge. Dynamic strain was measured in 4 steel plate-girder railway bridge during the trains was passing, which is located on the line of Kyoung-chun railway. And time history response analysis has been done in order to ensure actual survey. The results of this study show the decreased of the fatigue damage in steel railway bridge according to length of span. This paper ends is bases research of fatigue design in steel railway bridges according to span length.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.97-102
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• 2003

A real train load fluctuates along the track because of complicated movements(Bouncing, Rolling, Pitching and Yawing) and rail conditions. This research has for its object in development of a numerical real train load model including fluctuation characteristics of lateral forces. It is based on Klingel movement theory of a wheelset on straight track it presents a propriety of application by comparison between a 3D-Numerical analysis result using this train load model and a measured data. And this paper presents further study subject to improve a method about the train load modeling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.845-852
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• 2015

This study examined the flexural strength of CFS reinforced concrete beams with various load histories. The RC beams to be reinforced by CFS have undergone various loading histories but neglecting the loading history results in a few problems in structural safety and cost. Structural behavior of CFS-strengthened RC beams were analyzed considering the strain status of RC beams under loads at the time of CFS strengthening. Nonlinear section analysis showed that the flexural strength of CFS-strengthened RC beams depends on the load history of the RC beams. From the result of this analysis, the flexural strength of a CFS-strengthened concrete beam is affected considerably by the load history and should be considered in CFS reinforcement.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.1
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• pp.66-72
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• 2016

The aim of this paper is to investigate the characteristics of the signal of local ice load acting on side shell in the bow part due to ice broken by an icebreaker in ice-covered waters. The Korean icebreaking research vessel "ARAON" voyaged to the Arctic Ocean during the summer of 2010, and measurements of local ice load were carried out using several strain gauges. In this study, the time history of measured signals was analyzed and the characteristic values including rising time and half-decaying time were presented using non-dimensional parameters.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.22-27
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• 1997

In general, the load which acts on the structure is almost independent of time in many locations. In this case. It is difficult to estimate the life with the service load history, because the structure is on the multi- axial and multi-point loading states. In this study, the service load of the excavator which is widely used in industry field was calculated using measured cylinder pressures and displacements. The fatigue life was estimated using the multi-axial and multi-point load counting method. Service load history of 4 pin joint which act independently each other is yielded by mult-axial and multi-point load counting method. The stress spectrum is yielded by superposition of the results of FEM stress analysis applied unit load. Palm- gren-Miner's cumulative Damage is 0.000804 for Von Mises equivalent stress sequence by one side fillet weld S-N curve. This result agress with Bench test results. As a result of this study, the fatigue life esti- mation using the multi-axial and multi-axial and multi-point load counting method is useful.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.306-312
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• 2018

To navigate in ice-covered waters, the ice-breaking process is required. The ice-breaking mode depends on material properties of sea ice and ice conditions. The ice-breaking mode is classified into ramming and continuous ice-breaking. The ramming is effective on large ice features, such as thick ice ridge and icebergs, and the continuous ice-breaking is on level ice. In general, the impact time duration of crushing or bending on ice sheets is from 0.2 to 1.0 second. However, impact duration in ramming will be increased. The Korean ice-breaking research vessel ARAON conducted her research voyage in the Antarctic sea during the winter of 2012. The IBRV ARAON measured strain in ramming and continuous ice-breaking. Strain gauge signals were recorded during the planned ice-breaking performance and the unplanned ice transits in heavy ice conditions. The aim of this study is to investigate the ice load signals measured in ramming processes under the heavy ice condition. Based on the time history of the signals, a raising time, a half-decaying time and time duration were investigated and compared with the previous study which was suggested the five profiles of the ice load signals.

• Journal of Korean Society of Steel Construction
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• v.8 no.4 s.29
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• pp.19-29
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• 1996

In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.143-148
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• 2013

The aim of this study is to investigate the characteristics on the profile of local ice load acting on side shell of port side in bow part due to broken ice during icebreaking of ships in ice covered waters. The first Korean icebreaking research vessel 'ARAON' had a sea ice field trial in the Arctic Sea during early August, 2010, and the signals due to local ice impact measured from several strain gauges installed at bow part were gathered. It is known that these data with structural response characteristics due to local ice impact have some different characteristics with a typical hydraulic impact pressure - time history. In this study, the time history on the measured signals was analyzed and the characteristic values were presented using non-dimensional parameters.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.997-1002
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• 2007

A guideway vehicle is used in automobile, semiconductor and LCD manufacturing industries to transport products efficiently. Since the operating speed of the guideway vehicle should be increased for maximum productivity, the weight of the vehicle has to be reduced. This may cause parts in the system to fail before the life of the system. Therefore estimation of the fatigue life of the parts becomes an important problem. In this study, the fatigue life of the driving wheel in the guideway vehicle is estimated using a S-N curve. To obtain the fatigue life of a part, the S-N curve, load time history applied on a driving wheel and material property are required. The S-N curve of the driving wheel is obtained using the fatigue experiment on wheels. Load time history of the wheel is obtained from multibody dynamics analysis. To obtain the material properties of the driving wheel, which is composed of aluminum with urethane coating, a compression hardware testing has been done with the static analysis of the FE model. The fatigue life prediction using computational analysis model guarantees the safety of the vehicle at the design stage of the product.