Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Calculations of Flat Plate Deflections Considering Effects of Construction Loads and Cracking

시공하중 및 균열 효과를 고려한 플랫 플레이트의 처짐 산정

  • Kim, Jae-Yo (Dept. of Architectural Engineering, Kwangwoon University) ;
  • Im, Ju-Hyeuk (Housing Eng. Team, Samsung Engineering and Construction) ;
  • Park, Hong-Gun (Dept. of Architecture, Seoul National University)
  • 김재요 (광운대학교 건축공학과) ;
  • 임주혁 (삼성물산(주) 건설부문 주택ENG팀) ;
  • 박홍근 (서울대학교 건축학과)
  • Published : 2009.12.31
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Abstract

The structural designs of RC flat plates that have insufficient flexural stiffness due to lack of support from boundary beams may be governed by serviceability as well as a strength criteira. Specially, since over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction, a construction sequence and its impact on the slab deflections may be decisive factors in designs of flat plate systems. In this study, the procedure of calculating slab deflections considering construction sequences and concrete cracking effects is proposed. The construction steps and the construction loads are defined by the simplified method, and then the slab moments, elastic deflections, and the effective moment of inertia are calculated in each construction step. The elastic deflections in column and middle strips are magnified to inelastic deflections by the effective moment of inertia, and the center deflection of slab are calculated by the crossing beam method. The proposed method is verified by comparisons with the existing test result and the nonlinear analysis result. Also, by applications of the proposed method, the effects of the slab construction cycle and the number of shored floors on the deflections of flat plates under construction are analyzed.

테두리 보에 의한 휨강성이 확보되지 않은 철근콘크리트 플랫 플레이트의 구조설계는 강도 조건 뿐만 아니라 사용성에 의하여 지배받을 수 있다. 특히, 조기 재령 슬래브의 과하중 작용 및 균열 발생은 시공 중인 플랫 플레이트의 처짐을 크게 증가시키므로, 시공 순서 및 슬래브 처짐에 대한 영향은 플랫 플레이트 시스템 설계의 주요한 요소가 될 수 있다. 이 연구에서는 시공 순서 및 콘크리트 균열 효과를 고려한 슬래브 처짐 산정 과정을 제안한다. 시공단계 및 시공하중이 간편법에 의하여 정의되고, 각 시공단계별로 슬래브 모멘트 및 탄성 처짐, 유효단면2차모멘트가 계산된다. 주열대와 중간대에서의 탄성 처짐은 유효단면2차모멘트 효과에 의해 비탄성 처짐으로 증폭되며, 슬래브 중앙부 처짐은 교차보법에 의하여 산정된다. 제안된 방법은 기존 실험 결과 및 비선형 해석 결과와의 비교를 통하여 검증된다. 또한, 제안법의 적용을 통하여, 시공 중인 플랫 플레이트의 처짐에 대한 시공주기 및 동바리 지지 층 수의 영향이 분석된다.

Keywords

References

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  1. Parametric Study on Long-Term Deflections of Flat Plates Considering Effects of Construction Loads and Cracking vol.16, pp.1, 2012, https://doi.org/10.11112/jksmi.2012.16.1.044
  2. Reshoring effects on deflections of multi-shored flat plate systems under construction vol.45, pp.4, 2013, https://doi.org/10.12989/sem.2013.45.4.455