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오지택(Ji-Taek Oh),최진유(Jin-You Choi),김현민(Hyun-Min Kim) 한국철도학회 2002 한국철도학회 학술발표대회논문집 Vol.- No.-
Railway plate girder bridges have characteristics that are not show dominant frequency in dynamic response frequencies like obtained vertical acceleration on the bridge during the train passing because the train loading relatively bigger than the bridge self-weight. This paper experimentally confirmed in FFT result has various frequencies due to inherent characteristic of railway train loading. To establish classification of dynamic frequency range in railway bridge acceleration during the train passing, vibration frequencies result from experimental test are analyzed concerning actuation vibration factors. Factors are train velocity, train type, mass ratio of vehicle/bridge, stiffness of bridge, bridge/track and vehicle/track. From the result, it is proposed that the frequencty classfication table with corresponding factors. Using the proposed table to develop rehabilitation technique of the plate girder bridge, to expect vibration reduction and comfort enhancement of the railway plate girder bridge.
접속부의 강성완화를 위한 Approach zone의 매개분석
손지현(Son Ji Hyun),최진유(Choi Jin You),오지택(Oh Ji Taek),황원섭(Hwang Won Sup) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-
When vehicles pass the connection between the bridge and earthwork, the difference of both sections" stiffness produces an increasing wheelload. As a consequence, it results in the excessive vibration of vehicles and the damage of bearing system. In general, steel plate girder railway bridges without ballast track have larger stiffness than the bridge with ballast, and produces larger impulse on the bridge superstructure. Thus, it is necessary to reduce the differences of both stiffness. This study presents parametric studies on the behavior of plate girder bridges and their tracks by means of various stiffnesses and the length of approach zone. The results of numerical study showed that the smaller the stiffness of both sides and the longer the length of approach zone, the variation of wheelload becomes smaller. Hence, it gives less burden into the plate girder bridges and their tracks. It is expected that the results of parametric study can be used as a preliminary data for the determination of economical length on the approach zone and the stiffness of both sides.
오지택(Ji-Taek Oh),최진유(Jin-You Choi),김현민(Hyun-Min Kim) 한국철도학회 2002 한국철도학회 학술발표대회논문집 Vol.- No.-
A railway open deck plate girder bridge without ballast should support relatively heavier vehicle loads compared with its self-weight. For such a reason, actual dynamic response of the bridge is considerably differing with normal prediction because additional masses added from vehicle to a bridge have an effect on the dynamic characteristics of the bridge. These differences affect to the estimation of a natural frequency change that adopted for one of the evaluation technique of strength decrease, and these make trouble to the analysis of a natural frequency from the field test data that measured at the bridge subjected to a running vehicle. In this study, classification of mass participation ratio for each component of open deck plate girder bridge without ballast and the comparison according to the change of vibration characteristics for the case of subjected to a running vehicle were accomplished.
박문석(Moonsuk Park),오지택(Ji-Taek Oh),최진유(Jin-You Choi) 한국철도학회 2001 한국철도학회 학술발표대회논문집 Vol.- No.-
Static behaviors of railway plate girder bridges designed by the L-22, a standard load type of the railway specification in Korea, are evaluated by widely eight load cases. The load cases are three real loads, which contain three locomotive types of Saemaul PMC. diesel, and Korea Train Express(KTX), and three design loads, L-22, L-18. and HL-25 loads, in railway specification. Plate girders for analysis have the length of spans of six types : 6m, gm, 12m, 22m, 24m, and 30m. For analysis SAP2000n, a commercial FEM tool, is used. Dominant axial load types are taken from these results that are maximum deflections, reaction forces, and absolute maximum bending moment in girders.
오지택(Ji-Taek Oh),박문석(Moonsuk Park),최진유(Jin-You Choi) 한국철도학회 2001 한국철도학회 학술발표대회논문집 Vol.- No.-
Natural frequencies are studied for dynamic analysis of plate girder bridges which are made up about 34% in the existing railway bridges in Korea. In this study, standard plate girder bridges designed by L-22, a standard load type of the railway specification in Korea. are modeled for finite element method analysis. SAP2000n, a commercial finite element method analysis tool, is used for structural analyses and evaluations. Span lengths of plate girders have 7 types : 6m, 9m, 12m, 15m, 22m, 24m, and 30m. Natural frequencies are considered in mass rations and span lengths and they are compared with a recommendation of UIC 776-1R for alterations, from now on, in train conditions of operation. For changes of natural frequencies in plate girders by damages of structures, parameter studies are accomplished.
오지택(Ji-Taek Oh),박문석(Moonsuk Park),최진유(Jin-You Choi) 한국철도학회 2001 한국철도학회 학술발표대회논문집 Vol.- No.-
In this study, railway plate girder bridges are modeled in detail for finite elements within 3-dimension and analyzed by SAP 2000N, a commercial finite element analysis tool. Especially, loads of trains gained by statistical averages of measured true loads of trains are used for analysis. When the loads are adapted, the numerical dynamic responses are very close to real measurements. Resonant speed areas by train types are evaluated from the results of numerical analyses by different driving speeds of trains. For dynamic numerical analysis of railway bridges, reasonable guides are also discussed.