• Title, Summary, Keyword: 합성단면

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Sensitivity Analysis of Generalized Parameters on Concrete Creep Effects of Composite Section (합성단면의 콘크리트 크리프 효과에 대한 일반화 매개변수의 민감도 분석)

  • Yon, Jung-Heum;Kim, Eui-Hun
    • Journal of the Korea Concrete Institute
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    • v.21 no.5
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    • pp.629-638
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    • 2009
  • In this paper, the existing formulas of the step-by-step method were generalized for effective estimation of responses of complicated composite sections due to long-term deformation of concrete. The initial transformed section properties of the composite section were derived from material and section properties of concrete section and sections which confine the longterm deformation of concrete. The transformed section properties at each step were derived from the effective modulus of elasticity considered the creep coefficient variation. Improved formulas of the step-by-step method for generalized responses were derived by introducing 5 generalized parameters. The formulas can be more simplified by applying constant increment of creep coefficient at each step. The constant increment of creep coefficient at each step can also reduce computing time and make equal computing error of each step. The generalized responses for axial elastic strain of concrete section were most sensitive to the area rate of concrete section, and the ratio of the second moment of the confining section area was more sensitive than that of the concrete section. Those for elastic curvature of concrete section were most sensitive to the ratio of the second moment of concrete section area.

Proposed Limit State Design Method for Encased Composite Columns (매립형 합성기둥의 한계상태설계법 제안)

  • Kim, WonKi
    • Journal of Korean Society of Steel Construction
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    • v.9 no.4
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    • pp.523-533
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    • 1997
  • Current limit state design method for encased composite columns contains irrational and uncertain design equations in defining section and material properties of composite members. Through investigating previous research used in formulating the design equation, this paper explores the irrationality and uncertainty such as 1) transformation of yield stress and elastic modulus for composite section, 2) an equation influencing buckling strength in terms of area rather than moment of inertia, and 3) selection of larger radius of gyration between steel and concrete sections. Improving the design equations this paper proposes two design methods which can be directly used in practical design.

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Assessment of Structural Performance of Transparent Noise Barrier Consisting of Steel-FRP Composite Frame (강재-FRP 합성단면 프레임 투명방음판 구조성능 평가)

  • Lee, Dae-Yong;Kim, Jin-Kook;Kim, Sang-Ki
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.956-959
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    • 2007
  • 기존 투명방음판용 알루미늄 프레임의 구조적 단점을 보완할 수 있는 강재-FRP(Fiber Reinforced Plastic) 합성단면 구조재를 개발하였으며, 아울러 조립이 간편하고 외부 충격에 의해 쉽게 분리가 되지 않는 삽입형 수평재-수직재 코너연결부 상세를 개발하였다. 개발된 강재-FRP 합성단면 구조재와 코너연결재를 결합하여 프레임을 형성하고 그 사이에 투명패널을 삽입함으로써 길이 4m, 높이 1m 투명방음판 시작품을 완성하였으며, 이렇게 완성된 투명방음판 시작품을 대상으로 KS 4770-1 구조성능 평가시험을 수행하였다. 한국도로공사 교량부 시험하중에 대해 설계된 강재-FRP 합성단면 프레임 투명방음판의 구조성능 평가결과, FRP 의 추가적인 구조강성 증가 효과로 인해 한국도로공사 교량부 시험하중을 약간 상회하는 KS 2 호 등급시험하중까지도 만족시키고 있음을 확인할 수 있었다.

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Stress Relaxation Coefficient Method for Concrete Creep Analysis of Composite Sections (합성단면의 콘크리트 크리프 해석을 위한 이완계수법)

  • Yon, Jung-Heum;Kyung, Tae-Hyun;Kim, Da-Na
    • Journal of the Korea Concrete Institute
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    • v.23 no.1
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    • pp.77-86
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    • 2011
  • The concrete creep deformation of a hybrid composite section can cause additional deformation of the composite section and the stress relaxation of pre-compressive stress on the concrete section due to partial restraint of the deformation. In this study, the stress relaxation coefficient method (SRCM) is derived for simple analysis of complicate hybrid or composite sections for engineering purpose. Also, an equation of the stress relaxation coefficient (SRC) required for the SRCM is proposed. The SRCM is derived with the parameters of a creep coefficient, section and loading properties using the same method as the constant-creep step-by-step method (CC-SSM). The errors of the SRCM is improved by using the proposed SRC equation than the average SRC's which were estimated from the CC-SSM. The root mean square error (RMSE) of the SRCM with the proposed SRC equation for concrete with creep coefficient less than 3 was less than 1.2% to the creep deformation at the free condition and was 3.3% for the 99% reliability. The proposed SRC equation reflects the internal restraint of composite sections, and the effective modulus of elasticity computed with the proposed SRC can be used effectively to estimate the rigidity of a composite section in a numerical analysis which can be applied in analysis of the external restrain effect of boundary conditions.

Seismic Performance Assessment of a Modular System with Composite Section (합성단면을 적용한 모듈러 시스템의 내진 성능평가)

  • Choi, Young-Hoo;Lee, Ho-Chan;Kim, Jin-Koo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.2
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    • pp.69-77
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    • 2017
  • By producing pre-engineered modular system in the factory, It is enable to expedite construction and can be distinguished from two types by the method resisting load. One is the open-sided modular system composed of beams and columns. The other is enclosed modular system composed of panels and studs. Of the modular systems, the open-sided modular system buildings the connection between modules are difficult due to closed member sections, and the overall strength is reduced as a result of local buckling. In this study, in order to solve these problems, a modular system with folded steel members filled with concrete are proposed. The capacity spectrum method presented in ATC 40 is used for seismic performance assessment of the proposed model structure and the structure with conventional steel members. The analysis results show that at the performance point of each model the number and rotation of plastic hinge formed in the proposed modular system are smaller than those in the conventional system. Based on this observation it is concluded that the proposed system with composite sections has superior seismic capacity compared with conventional system.

Optimum Design of Composite Framed Structures Based Reliability Index (신뢰성지수를 고려한 합성 뼈대구조물의 최적설계에 관한 연구)

  • Jung, Young Chae;Kim, Jong Gil
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4
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    • pp.389-401
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    • 2003
  • The purpose of this study is to develop an algorithm, which can be designed the optimal sections of the composite framed structures constituted with the beams and the columns consisted of H type of steel section and concrete considering the reliability index. The optimized problem or the composite framed structures is formulated with the objective function and the constraints taking the section sizes as the design variables. The objective functions are constituted by the total costs of constructions. Also, the constraints are derived by considering the reliability index of section stress and allowable stress. The algorithm optimized the section of the composite framed structures utilizes the SUMT method using the modified Newton-Raphson direction method. The optimizing algorithm developed in this study is applied to the numerical examples with respecting a one-bay, one-story composite framed structure and a one-bay five-story one for the practical utilization of design on the composite framed structures using the reliability indices$({\beta})$ three and zero. In addition, their numerical results are compared and analyzed to examine the possibility of optimization the applicability, and the convergence this algorithm.

Seismic coda waves for gas-hydrate seismic data (가스 하이드레이트 탄성파 자료 코다 파 (coda waves) 연구)

  • Jang, Seong-Hyung;Suh, Sang-Yong;Kim, Young-Wan
    • 한국신재생에너지학회:학술대회논문집
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    • pp.497-500
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    • 2007
  • 탄성파 코다 파는 두 수진기에서 기록된 탄성파 자료의 상호상관으로부터 두 신호에 대한 순간응답을 구하고 이로부터 지층정보를 구하는데 이용된다. 여기에서는 인공합성 탄성파 자료와 가스 하이드레이트 현장자료에 적용하여 상호상관 모음도와 가상음원 모음도 (virtual source)를 구하고자 하였다. 인공합성자료는 해저면 탄성파 탐사법 (ocean bottom seismic)을 모델로 이용하여 인공합성 탄성파 단면도를 제작하였으며, 탄성파 코다 파를 살펴보기 위해 인공 OBS 자료 중 첫 번째 트레이스를 가상음원으로 정하고 모든 음원 모음도와 상호상관으로 가상응원 단면도를 제작하였다. 현장자료 적용으로는 해저면 기인 고진폭 반사파인 BSR (bottom simulating reflection)을 포함하고 있는 자료를 선정하여 상호상관 단면도와 가상음원 단면도를 제작하였다. 중합단면도상에 나타난 가스 분출지역은 상호상관 단면도에서도 나타났으며, 중합단면도상 BSR부분은 vs 단면도에서 강한 반사파를 보여줌을 알 수 있었다.

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Flexural Strength of Composite HSB Hybrid Girders in Positive Moment (HSB 강재 적용 강합성 복합단면 거더 정모멘트부의 휨저항강도)

  • Cho, Eun-Young;Shin, Dong-Ku
    • Journal of Korean Society of Steel Construction
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    • v.23 no.3
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    • pp.385-395
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    • 2011
  • The flexural strength of composite HSB hybrid I-girders under positive moment is investigated by the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specification to such girders. The hybrid girders are assumed to have the top flange and the web fabricated from HSB600 steel and the bottom flange made of HSB800 steel. More than 6,200-composite I-girder sections that satisfy the section proportion limits of AASHTOL RFD specifications are generatedby the random sampling technique to consider a statistically meaningful wide range of section properties. The flexural capacities of the sections are calculated by the nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels are modeled as an elastoplastic, strain-hardening material and the concrete as CEB-FIP model. The effects of ductility ratio and compressive strength of concrete slab on the flexural strength of composite hybrid girders make of HSB steels are analyzed. Numerical results indicated that the current AASHTO-LRFD equation can be used to calculate the flexural strength of composite hybrid girders fabricated from HSB steel.

Restraint Coefficient of Long-Term Deformation and loss Rate of Pre-Compression for Concrete (콘크리트 장기변형의 구속계수와 선압축력의 손실률)

  • 연정흠;주낙친
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.521-529
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    • 2002
  • A restraint coefficient for creep and dry shrinkage deformation of concrete in a composite section was derived to calculate the residual stress, and an equation for the loss rate of the pre-compression force was proposed. The derived restraint coefficient was computed by using the transformed section properties for the age-adjusted effective modulus of elasticity. The long-term behavior of complicate composite sections could be analyzed easily with the restraint coefficient. The articles of the current design code was examined for PSC and steel composite sections. The dry shrinkage strains of $150 ~ 200$\times$10^{-6}$ for the computations of the statically indeterminate force and the expansion joint could be under-estimated for less restrained sections such as the reinforced concrete. The dry shrinkage strain of $180$\times$10^{-6}$ for the computation of residual stress in the steel composite section was unreasonably less value. The loss rate of 16.3% of the design code for the PSC composite section in this study was conservative for the long-term deformation of the ACI 205 but could not be used safely for that of the Eurocode 2. For pre-compressed concrete slab in the steel composite section, the loss rate of prestressed force with low strength reinforcement was much larger than that with high strength tendon. The loss rate of concrete pre-compression increased, while that of pre-tension decreased due to the restraint of the steel girder.

A Study on Optimum Section of New Type Steel-Concrete Composite Beam (신형상 층고절감형 합성보의 최적단면 도출에 관한 연구)

  • Yoon, Myung-Ho;Lee, Yoon-Hee
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.2 no.3
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    • pp.30-35
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    • 2011
  • This study investigates the optimum section properties of newly developed steel-concrete composite beam. For that purpose we developed computer program calculating section properties. The suggested new beam section highly contribute to save inter-story height and reduce construction duration and cost compared with conventional steel works such as H-beam and column + RC slab system. But the section shape have different section modulus with upper and lower fiber because of the unsymmetric cross section. Therefore the parametric study on thickness-ratio of top and bottom flange plate is needed. In this paper the change of neutral axis and section modulus for thickness-ratio of up and down flage plate is analysed and discussed.