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Design of Prestressed W-Shape Beams with a Separated Prestressing Cover Plate
김기동,안효일,한기장,Dong Seong Kim 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2
Prestressed steel beams with a prestressing cover plate (PBCP), which are expected to overcome the limitations of prestressed steel girders using tendons, were investigated in this study. Experiments and fi nite element analyses (FEA) were performed to present a design procedure. The maximum compressive force according to fl ange slenderness, which could be applied to steel beams subjected to bending moment due to ultimate load, was investigated for rolled W-shape beams. The fl exural capacity and elastic fl exural stiff ness of steel beams could be signifi cantly increased by using a cover plate attached at a fi xed distance from the bottom fl ange of a steel beam as a prestressing member. A PBCP with W920 × 1377 could achieve a maximum span of 72 m for a two-lane, single-span composite bridge with fi ve girders when the span-to-depth ratio is limited to around 38.0, whereas an ordinary composite beam with the same W-shape section, having a span-to-depth ratio of 36.0, could achieve a maximum span of around 50 m. The limitations of maximum bridge length, minimum steel amount and maximum span-to-depth ratio that rolled fl exural members can achieve were able to be effi ciently overcome by using the PBCP. The span-to-depth ratio of PBCPs was about 2.08 times larger on average than that of plate girders for bridge lengths of 50 m to 72 m. The PBCP could employ a smaller steel volume than plate girders for the same span-to-depth ratio. Therefore, it could be seen that the PBCP could be an alternative to plate girders for the limited span-to-depth ratio and even for the cost effi ciency.
金起東 東國大學校 1964 論文集 Vol.1 No.-
1. The conception of the philosophy of history. "Philosophy of history" was invented in the 18th century by Voltaire (1694-1778), but its thought has already been in some Greek philosophers. The problems of the philosophy of history must be invented: What is the history?, how do we know it?, What can history do?, if it is progressing. Has the history the Rules or not? Consequently, it must be inquired to the science of history, Metaphysics and Epistemology. 2. The meaning of history. The Greek 'historia' means "a learning by inquiry", and "knowledge or information obtained by inquiry". But "what" must be involved in those problems. I think, history would be meant; 1)the eveuts occured in past. 2) the description of events. 3) our existence. 3. The Revolution Generally, the revolution is the reformation of history. "Revolution" is reduced to the "evolution". it must be the moment to "affairs" (as problems). It means historical time, being Existenz ("self-awakening"). Another words it is "Time-Space" or "Space-Time", meant "now and here" Thereefore, revolution awakens the time in history. Hereto, Truth and Good are recognizable. 4. The subject of history. The subject of history is that of revolution or value. The value always is not settled. In history, however, the value is settled by the times and it is good for mankind. Generally, value is not settled, if so, I express it as "Mu"(nothing). 5. The cognition of history. The cognition of history is that of historical events, but only when historical events is chosen, it must be the problems of historical subject and it must have historical point of view. 6. The iudividual in history. The man puts into the history through the transcendental Ego existence. I represent it as reducing to "Mu"(nothing) and this status Would be represented as Korean "Shaisamsurei". "Shaisamsurei" means the moment reducing to "Mu"(nothing).