• Title, Summary, Keyword: 처짐

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Measurement and Prediction of Long-term Deflection of Flat Plate Affected by Construction Load (시공하중에 의한 플랫 플레이트의 장기처짐 계측 및 해석)

  • Hwang, Hyeon-Jong;Park, Hong-Gun;Hong, Geon-Ho;Kim, Jae-Yo;Kim, Yong-Nam
    • Journal of the Korea Concrete Institute
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    • v.26 no.5
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    • pp.615-625
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    • 2014
  • Excessive long-term slab deflection caused by construction load is a critical issue for the design of concrete slabs, as long span flat plates become popular for tall buildings. In the present study, the effect of construction load causing early slab cracking on the long-term deflection was theoretically studied. On the basis of the result, a numerical analysis method was developed to predict the long-term deflection of flat plates. In the proposed method, immediate deflection due to slab cracking and long-term effect of creep and shrinkage were considered. To verify the construction load effect, long-term slab deflections were measured in actual flat plate buildings under construction. The results showed that the immediate deflection due to the construction load increased significantly the long-term deflection. The proposed method was used to predict the deflections of the buildings. The results were compared with the measurement results. The predictions agree well with the long-term deflections of flat plate affected by construction load.

Numerical Analysis of Large Deflections of Cantilever Beams (캔틸레버 보의 과대처짐 해석)

  • Lee, Byoung Koo
    • Journal of The Korean Society of Civil Engineers
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    • v.10 no.1
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    • pp.1-7
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    • 1990
  • A method is developed for solving the elastica of cantilever beam subjected to a tip point load and uniform load. The Bernoulli-Euler differential equation of deflected beam is used. The Runge-Kutta method and the Regula Falsi method are used to perform the integration of the differential eqution and to determine the horizontal deflection, respectively. The horizontal and vertical deflections of the free end, and the free-end rotations are calculated for a range of parameters representing variations in tip point load and uniform load. All results are presented in nondimensional forms. And some typical elastic are also presented.

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An Estimation of Panel Deflection at Engine Room Upper Deck for the Ship Under Construction (건조중인 선박에서의 기관실 상갑판 판부재의 처짐 예측)

  • Juh-H. Ham;Ul-N. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.31 no.3
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    • pp.119-128
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    • 1994
  • Deflection estimation at engine room upper deck panel is performed for the actual ship structure. These deflection behaviours are basically investigated from not only the data based on the full series results of nonlinear analysis using Incremental Galerkin's Method but also actual deflection data measured from damaged ship under construction in dry dock. The effects of residual stress, initial deflection and static loading are also included. The computed estimation results of upper deck plate panel including theme effects are shown that upper deck platings of new ship expected less deflection magnitude than damaged ship.

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Simplified Evaluation of Long-Term Deflection of Reinforced Concrete Flexural Members (철근콘크리트 휨재의 장기처짐 예측을 위한 간략 평가)

  • Chang, Dong-Woon;Kang, Jee-Hoon;Chae, Seung-Yoon;Kim, Jae-Yo;Eom, Tae-Sung
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.6-9
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    • 2011
  • 지속하중을 받는 철근콘크리트 휨부재는 크리프, 건조수축 등 장기거동에 의하여 처짐이 증가된다. ACI318-08, KCI 2007 등 현행 구조설계기준의 장기처짐 평가방법은 인장 및 압축 철근비, 배근상세, 재료 강도 등 설계변수에 따른 장기처짐의 변화를 합리적으로 고려하기 어렵다. 본 연구에서는 장기거동에 의한 힘의 평형조건과 변형률 적합조건을 사용하여 크리프와 건조수축에 의한 철근콘크리트 균열단면의 장기변형을 예측하는 간략 평가식을 제안하였다. 장기변형 평가 시 콘크리트와 철근은 선형탄성거동을 가정하였고, 시간에 따른 콘크리트와 철근 사이의 응력재분배를 고려하기 위하여 재령보정탄성계수법을 적용하였다. 변수연구 및 검증 결과, 철근콘크리트 휨재의 장기처짐은 설계변수의 영향으로 달라질 수 있고, 제안된 방법은 이러한 장기처짐의 변화를 비교적 정확하게 예측하는 것으로 나타났다.

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Partial Composite Action of Gypsum-Sheathed Cold-Formed Steel Wall Stud Panels (석고보드와 결합된 강재 샛기둥 패널의 부분 합성거동)

  • Lee, Young Ki
    • Journal of Korean Society of Steel Construction
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    • v.13 no.4
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    • pp.373-380
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    • 2001
  • The problem addressed in this study is how to analytically treat the partial composite action for wall panels. An equation, derived for wood-joist floor systems, which determines deflections for beams with partial composite action is introduced. The equation is applied to the calculation of the mid-span deflection for gypsum-sheathed, cold-formed steel was stud panels. The objective of this study is to properly reflect the influence of the following factors in the calculation of mid-span deflection for the panel: connection slip, local buckling, perforations in the stud web, and effects from joints in the sheathing. Predicted deflections based on an upper bound for connection rigidity were closest to experimental deflections.

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An Iterative Method to Determine Deformed Shape of Cable (케이블 처짐 형상 결정을 위한 반복 계산법의 개발)

  • 정진환;조현영;박용명;계만수
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.4
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    • pp.715-725
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    • 2002
  • In this study, a method to determine the deformed shape of planar cable under vertical loads was presented. To obtain the deformed shape of cable by general cable theorem, a sag at arbitrary point is usually given. However, in general cases without a given sag, the proposed method determines the deformed shape of cable based on the equations of cable theorem and geometric compatibility by iterative way. The method was also extended to slove extensible cable. It was acknowledged from numerical analysis and model tests in laboratory that the proposed method is valid lot analysis of extensible cable as well as unextensible cable.

Deflection Limit for a Maglev Railway Guideway Considering Ride Comfort (승차감을 고려한 자기부상철도 가이드웨이 구조물의 처짐 한계)

  • Lee, Jin Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.33 no.6
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    • pp.367-374
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    • 2020
  • A standard for the vibration magnitude of a maglev train is presented herein to ensure a comfortable ride for the passengers. The vibration magnitude is determined from the vertical acceleration of the car body. A parameter analysis of the maglev train system is then performed considering the vehicle-structure interaction, and a deflection limit of L/1300 is proposed to satisfy the standard for the vertical acceleration. The proposed deflection limit is applied to the dynamic analysis of the actual maglev train system to assess applicability. Compared with the existing standard for the guideway structure, the proposed deflection limit is expected to enable economical design and construction.

Limit Span/Depth Ratio for Indirect Deflection Control in Reinforced Concrete Flexural Members (철근콘크리트 휨부재의 처짐 간접제어를 위한 한계 지간/깊이-비 연구)

  • Choi, Seung-Won;Kim, Woo
    • Journal of The Korean Society of Civil Engineers
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    • v.31 no.1A
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    • pp.35-41
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    • 2011
  • In concrete structural design provisons, two methods are normally provided to control deflection; direct method and indirect method. It is more efficient to use the indirect deflection control by which the span/depth ratio is limited not to exceed an allowable deflection limit. Because actual deflections are affected by many causes, it is complicated to evaluate actual deflections. In this study, limit span/depth ratios are derived from the deflection calculated directly at the serviceability limit state in RC members. The deflection is obtained from using average curvature, which depends on materials model used. The main variables examined are tension stiffening effect, concrete strength, cross section size and compressive steel ratio. It could be appeared that more analytical consistency is secured to use the 2nd order form of tension stiffening effect. And the limit span/depth ratio is dependent on material strength, tensile and compressive steel ratio but it is independent on cross-section size.

Evaluation on Expectation of Deflection of Floor Damping Materials Subjected to Long-Term Load (장기하중을 받는 바닥완충재의 처짐 예측 평가)

  • Kim, Jung-Min;Hong, Yoon-Ki;Kim, Jin-Koo;Lee, Jung-Yoon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.4
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    • pp.19-26
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    • 2016
  • Floor damping materials used in floating floor system to diminish the floor noise have been made with low density and dynamic stiffness. Owing to this low density and dynamic stiffness, the deflection in these materials under long-term loading and cracking of the floor finishing mortar in the floating floor system may occur. This paper presents the results of long-term loading effects on the deflection of different types of floor damping materials. The experimental program involved the long-term loading tests for 490 days loading period on sixteen specimens. Specimens were classified as DM1(Damping Materials) to DM8, depending upon the four main parameters; types, bottom shapes and densities of floor damping materials and amount of loading. Results indicated that the long-term deflection of all specimens of damping materials remained unchanged after 200 days at all loading amounts, except the specimens made up of Polystrene, in which long-term deflection remained unchanged after 160 days at 250 N load and 100 days 500 N load. In this paper, two types of correlation expressions were shown in the deflection range prior to the range where deflection remained constant; two analyses by ISO 20392 and linear regression. In comparison of two analyses and experimental results on the difference of deflection of 16 specimens, the difference of deflection was below 0.4 mm in those analyses in case of that total deflection was below 10 mm. Restrictively, it was judged that the analysis for the deflection of specimens made up of Polystrene is more appropriate using ISO 20392.

Prediction of the Static Deflection Profiles on Suspension Bridge by Using FBG Strain Sensors (FBG 변형률센서를 이용한 현수교의 정적 처짐형상 추정)

  • Cho, Nam-So;Kim, Nam-Sik
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.5A
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    • pp.699-707
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    • 2008
  • For most structural evaluation of bridge integrity, it is very important to measure the geometric profile, which is a major factor representing the global behavior of civil structures, especially bridges. In the past, because of the lack of appropriate methods to measure the deflection profile of bridges on site, the measurement of deflection has been restricted to just a few discrete points along the bridge, and the measuring points have been limited to the locations installed with displacement transducers. Thus, some methods for predicting the static deflection by using fiber optic strain sensors has been applied to simply supported bridges. In this study, a method of estimating the static deflection profile by using strains measured from suspension bridges was proposed. Based on the classical deflection theory of suspension bridges, an equation of deflection profile was derived and applied to obtain the actual deflection profile on Namhae suspension bridge. Field load tests were carried out to measure strains from FBG strain sensors attached inside the stiffening girder of the bridge. The predicted deflection profiles were compared with both precise surveying data and numerical analysis results. Thus, it is found that the equation of predicting the deflection profiles proposed in this study could be applicable to suspension bridges and the FBG strain sensors could be reliable on acquiring the strain data from bridges on site.

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