• Title/Summary/Keyword: Precast concrete beam

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Initial Stiffness of Beam Column Joints of PCS Structural Systems (PCS 구조 시스템 접합부의 초기 강성에 대한 연구)

  • Park, Soon-Kyu;Kim, Moo-Kyung
    • Journal of the Korea Concrete Institute
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    • v.20 no.3
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    • pp.271-282
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    • 2008
  • Specific joint devices composed of end-plates and through bolts are under development to assemble steel beams to PC columns efficiently by dry construction method for the PCS structural system, of which major structural components are precast concrete columns and steel beams. Seismic performance of the joint devices had been evaluated by experimental tests in the previous studies and it was showed that all the performance requirements regarding to strength deterioration, stiffness degradation and energy dissipation capacity were satisfied to the criteria of ACI requirements, but the initial stiffness was not. In order to find out possible causes of the insufficient rigidity of the joint devices and provide the proper measures to improve the performance of the joint accordingly, numerical analyses were carried out by using ABAQUS. Parameters, such as thickness of neoprene pad, conditions of surface between PC column and end-plate, magnitude of pretension forces of through bolts, stiffness of end-plate were taken into consideration. As the result, it was found that the rigidity of the PCS system was negatively affected by the magnitude of initial gaps between PC columns and end-plates, and insufficient stiffness of neoprene fillers and end plates. In order to improve the initial stiffness performance of the joints, measures such as increase of the magnitude of pretension forces on through bolts and increase of the stiffness of end-plate by reducing the bolt pitch and providing adequate stiffeners are recommended.

Seismic Performance of Precast Infill Walls with Strain-Hardening Cementitious Composites (변형경화형 시멘트 복합체를 사용한 프리캐스트 끼움벽의 내진성능)

  • Kim, Sun-Woo;Yun, Hyun-Do;Jang, Gwang-Soo;Yun, Yeo-Jin
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.327-335
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    • 2009
  • In the seismic region, non-ductile structures often form soft story and exhibit brittle collapse. However, structure demolition and new structure construction strategies have serious problems, as construction waste, environmental pollution and popular complain. And these methods can be uneconomical. Therefore, to satisfy seismic performance, so many seismic retrofit methods have been investigated. There are some retrofit methods as infill walls, steel brace, continuous walls, buttress, wing walls, jacketing of column or beam. Among them, the infilled frames exhibit complex behavior as follows: flexible frames experiment large deflection and rotations at the joints, and infilled shear walls fail mainly in shear at relatively small displacements. Therefore, the combined action of the composite system differs significantly from that of the frame or wall alone. Purpose of research is evaluation on the seismic performance of infill walls, and improvement concept of this paper is use of SHCCs (strain-hardening cementitious composites) to absorb damage energy effectively. The experimental investigation consisted of cyclic loading tests on 1/3-scale models of infill walls. The experimental results, as expected, show that the multiple crack pattern, strength, and energy dissipation capacity are superior for SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.