• Title, Summary, Keyword: 유효강성

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A Study on Experimental Determination for Effective Stiffness of Power Transmission System (동력전달계 유효강성의 실험적 결정에 관한 연구)

  • 임원식;조한상;박영일;이장무
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.51-55
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    • 1995
  • 본 연구에서는 회전동력전달계의 진동특성을 해석하고 이를 설계자료로 이용하기 위하여, 계 전체의 유효강성행렬 (effective stiffness matrix)을 실험적으로 결정할 수 있는 방법을 제안하였다. 이것은 비교적 측정이 용인한 관성행렬이 알려져 있다고 가정한 경우 기존의 선형 모델링을 그대로 이용하고, 위의 모든 기계요소의 해석이 불가능한 강성들을 포함한 등가강성(equivalent stiffness)으로 구성된 계의 유효강성행렬을, 실험에 의해 얻어진 계의 여러 작동상황과 이에 따른 고유진동수에 매칭(matching)시켜 결정하는 것이다. 또한, 이의 검증을 위하여 유성기어와 클러치로 이루어진 가상의 동력전달계를 구성하고 이의 시뮬레이션 결과를 이용하여, 유효강성 결정법을 통해 얻어진 등가강성들과 실제값들의 비교함으로서 그 신뢰도를 추정하였다.

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A Study on the Correlation between the Prestress Force and the Effective Rigidity of the Bonded Tendon (부착식 텐던의 긴장력과 유효 강성의 상관성 연구)

  • Jang, Jung-Bum;Lee, Hong-Pyo;Hwang, Kyeong-Min;Song, Young-Chul
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.641-644
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    • 2010
  • 프리스트레싱 시스템이 도입된 구조물의 사용수명이 오래됨에 따라, 이들 구조물의 잔존수명 평가와 보수 및 보강 등의 유지관리 차원에서 프리스트레싱 시스템의 현재 긴장력에 대한 평가는 매우 중요한 현안이 되어왔다. 따라서, 본 논문에서는 프리스트레싱 시스템의 현재 긴장력을 평가하기 위한 첫 단계로서 프리스트레싱 시스템의 긴장력이 구조계의 강성에 미치는 영향을 평가하였다. 이를 위하여 부착식 텐던 형식의 프리스트레싱 시스템이 도입된 시험체를 대상으로 SIMO sine sweep test를 수행하고 긴장력과 시험체의 유효 강성에 대한 상관성을 규명하였다. 그 결과, 프리스트레싱 시스템의 긴장력은 시험체의 유효강성을 증가시키며, 저차 고유진동수가 긴장력과 높은 상관성을 지니는 것으로 나타났다.

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Stiffness Reduction Factor for Post-Tensioned Flat Plate Slabs under Lateral Loads (횡하중하의 포스트 텐션 플랫 플레이트 해석을 위한 강성감소계수)

  • Park, Young-Mi;Park, Jin-Ah;Han, Sang-Whan
    • Journal of the Korea Concrete Institute
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    • v.21 no.5
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    • pp.661-668
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    • 2009
  • Effective beam width model(EBWM) has been used for analysis of post-tensioned(PT) flat plate slab frames under lateral loads. The accuracy of this model in predicting lateral drifts and unbalanced moments strongly depends on the estimated effective stiffness of PT flat plate slabs. As moments on the slab due to lateral loads increases, cracks occur which leads to stiffness reduction in slabs. For analyzing PT flat plate slab structure under lateral loads with good precision, reduction in slab stiffness has to be accurately estimated for EBWM. For this purpose, this study collected test results of PT flat plate system conducted by former researches. And this study reduced the width of slab so that the stiffness of the EBWM converged into the lateral stiffness of each test specimens by trial and error. By conducting nonlinear regression analysis using the stiffness ratio of the reduced width of slab to the effective width of EBWM with respect to the level of slab moments, an equation for calculating stiffness reduction factor for slab is proposed. For verifying the accuracy of the proposed equation, this study compared with the test result of the PT flat plate frame. It is shown that the EBWM with the proposed equation predicts the actual stiffness of the PT specimen which varied according to the level of applied moment.

Effective Stiffness of Composite Beams Considering Shear Slip Effects (전단슬립 효과를 고려한 합성보의 유효강성)

  • Heo, Byung Wook;Bae, Kyu Woong;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.16 no.5
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    • pp.671-682
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    • 2004
  • This study investigated the effects of a shear slip on the deflection of steel-concretecomposite beams with partial shear interaction. Under the guidance of various current design codes, this deflection was related to the strength of shear connectors in the composite beams. In this paper, a shear connector stiffness based on exact solutions, regardless of loading conditions, was developed. The equivalent rigidity of composite beams that considered three different loading types was first derived, based on equilibrium and curvature compatibility, from which a general formula accounting for slips was developed. To validate this approach, the predicted maximum deflection under the proposed method was compared against currently used equations to calculate beam effective stiffness (AISC)Nie's equations, which have recently been proposed. For typical beams that were used in practice, shear slips might result in stiffness reduction of up to 18% for short-span beams. For full composite sections, the effective section modulus with the AISC specifications was larger than that of the present study, which meant that the specifications were not conservative. For partial composite sections, the AISC predictions were more conservative than those in the present study.

Analysis of Effective Flexural Rigidity of Corrugated Steel-Concrete Composite Deck with I-beam Welded (I형강으로 보강된 강합성 절곡 바닥판의 유효 휨강성 분석)

  • Son, Chang-Du;Hong, Sung-Nam;Park, Jun-Myung;Park, Sun-Kyu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.3
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    • pp.145-154
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    • 2009
  • Steel-Concrete Composite Deck with I-beam welded is lighter and easier to construct than conventional in situ reinforced concrete slabs due to the I-beam embedded in the corrugated slab. For the calculation of effective flexural rigidity of conventional reinforced concrete structures, methods suggested in Design Standard for Roads and Bridges and ACI have been used. In this paper, the calculation methods were applied to steel-concrete composite deck with I-beam welded and then results of the steel-concrete composite deck were compared with those of reinforced concrete slabs. In addition, applicability of the methods to steel-concrete composite deck with I-beam welded was estimated. In order to compare the effective flexural rigidity, flexural experiments were conducted. Fifteen slabs were built and the variables considered in the experiments were studs, length of the slab, shape of the section and connecting methods.

Mechanical Properties Prediction by Geometric Modeling of Plain Weave Composites (평직 복합재료의 기하학적 모델링을 통한 기계적 물성 예측)

  • Kim, Myung-jun;Park, Jung-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.11
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    • pp.941-948
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    • 2016
  • Textile composite materials have been widely applied in aerospace structures due to their various advantages such as high specific stiffnesses and strengths, better out-of-plane performances, impact and delamination resistances, and net shape fabrications. In this paper, a modified geometric model of repeating unit cell (RUC) is suggested based on the Naik's model for 2D plain weave textile composites. The RUC geometry is defined by various parameters. The proposed model considers another parameter which is a gap length between adjacent yarns. The effective stiffnesses are predicted by using the yarn slicing technique and stress averaging technique based on iso-strain assumption. And the stiffnesses of RUC are evaluated by adjusting the gap ratio and verified by comparing with Naik's model and experimental data for 2D plain weave composite specimens.

Stiffness Prediction of Flatplate System According to Column Section Shape (기둥단면 형상에 따른 무량판 구조시스템 강성예측)

  • Lee, Do-Bum;Lee, Li-Hyung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.5
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    • pp.194-202
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    • 2006
  • In the present study, stiffness prediction methodologies for flat-plate structures were evaluated in comparison with the experimental results on the full-scale slab-column connections of flat-plate structures. The methodologies are as follows: the methodology proposed by Jacob S. Grossman and the methodology proposed by Choi & Song. The former does not predict the stiffness change of the slab-column connection due to the change in the column section shape and the latter overestimates the stiffness when edge length of the column section in the loading direction is long. In the present study, the equation to calculate the effective width of slabs was modified to reflect the effect of the change in the column section shape.

Effective Beam Width for Flat-Plate Systems Having Edge Beams under Lateral Loads (수평하중을 받는 테두리보가 있는 플랫플레이트 시스템의 유효보폭계수)

  • Han, Sang-Whan;Cho, Ja-Ock;Park, Young-Mi
    • Journal of the Korea Concrete Institute
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    • v.20 no.2
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    • pp.213-219
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    • 2008
  • The purpose of this study is to propose frame analysis method for flat plate slabs having edge beam under lateral loads. Flat plate system is defined as the system only with slab of uniform thickness and column. However, the slab system generally incorporate edge beams at exterior connection in actual design. ACI 318 (2005) allows three methods for conducting flat plate system analysis subjected to lateral loads. There are the finite element method (FEM), the equivalent frame method (EFM), and the effective beam width method (EBWM). Among methods, the EBWM enables us to analyze practically by substituting the actual slab to beam element. In this model, the beam element has a thickness equal to that of the slab, and effective beam width equal to some fraction of the slab transverse width. However, the established EBWM was generally proposed for variables of geometry or stiffness reduction factor and seldom proposed for the effect of edge beams. This study verifies that, in the case of flat plate system having edge beams at exterior connections, the lateral stiffness is considerably larger than without edge beams. Therefore it need to analysis method for considered the effect of edge beams. In this study, an analysis model is proposed for the flat plate system having edge beams under lateral loads by considering the effect of edge beams. To verify the accuracy of proposed model, this study compared results of the proposed EBWM with results of FEM of flat plate systems having edge beams under lateral loads. Also, the proposed approach is compared with experimental results of former research.

Performance Based Design of Coupling Beam Considering Probability Distribution of Flexural and Shear Strength (휨강도와 전단강도의 확률분포를 고려한 연결보의 성능기반설계)

  • Kim, Yun-Gon;Cho, Suk-Hee
    • Journal of the Korea Concrete Institute
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    • v.25 no.5
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    • pp.509-516
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    • 2013
  • In this paper, performance based design of coupling beam using non-linear static analysis is proposed considering probability distribution of flexural and shear strength in order to develop flexural hinge. This method considers post-yielding behavior of coupling beam and stress redistribution of system. It can verify the reduced effective stiffness to meet the current design requirement based on linear analysis. It also evaluates the lateral displacement under service load (un-factored wind load) properly. In addition, it can optimize the coupled shear wall system by taking stress redistribution between members into account. For a simplified 30-story building, non-linear static (push-over) analysis was performed and the structural behavior was checked at performance point and several displacement steps. Furthermore, system behavior according to the amount of reinforcement and depth of coupling beam was explored and compared each other.