• Title/Summary/Keyword: 모멘트-곡률

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Nonlinear Analysis of RC Beams under Cyclic Loading Based on Moment-Curvature Relationship (모멘트-곡률 관계에 기초한 반복하중을 받는 철근콘크리트 보의 비선형 해석)

  • 곽효경;김선필
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.2
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    • pp.245-256
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    • 2000
  • A moment-curvature relationship to simulate the behavior of reinforced concrete beam under cyclic loading is introduced. Unlike previous moment-curvature models and the layered section approach, the proposed model takes into consideration the bond-slip effect by using monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The advantages of the proposed model, comparing to layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures. The modification of the moment-curvature relation to reflect the fixed-end rotation and pinching effect is also introduced. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

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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.

Modeling and Parametric Studies on Moment-Curvature Relation of a Reinforced Concrete Column Subject In Axial-toad and Bi-Axil Moment (축하중과 이축모멘트를 받는 철근콘크리트 기둥의 모멘트-곡률에 관한 모델링 및 변수고찰)

  • 이차돈;최기봉;차준실;김성진
    • Journal of the Korea Concrete Institute
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    • v.14 no.5
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    • pp.677-688
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    • 2002
  • A analytical model is developed which can simulate a complete inelastic biaxial moment-curvature relations of a reinforced concrete column. The model can simulate sudden drop in moment capacity after peak moment and due to spalling of cover concrete. Parametric studies are performed examine the effects of constituent material properties as well as topological arrangement of reinforcements on moment-curvature relations and P-M interaction curve. It has been analytically observed that ductility of a reinforced concrete column is influenced mostly by magnitude of the axial load and spacings or the volume of lateral reinforcements. Compared to ACI P-M interaction curve, overall increase about 10% in square root of sum of squares of axial force and moment, and about 20% in peak load are observed for the columns reinforced according to ACI seismic design code.

Nonlinear Analysis of RC Beams Considering Fixed-End Rotation due to Bond-Slip (부착슬립에 의한 강체변형을 고려한 철근콘크리트 보의 비선형해석)

  • Kim, Sun-Pil;Kwak, Hyo-Gyoung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.1
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    • pp.1-12
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    • 2005
  • An analytical procedure to analyze reinforced concrete (RC) beams subject to monotonic loadings is proposed on the basis of the moment-curvature relations of RC sections. Unlike previous analytical models which result the overestimation of stiffnesses and underestimation of structural deformations induced from ignoring the shear deformation and assuming perfect-bond condition between steel and concrete, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end. The advantages of the proposed relation, compared with the previous numerical models, are on the promotion in effectiveness of analysis and reflection of influencing factors which must be considered in nonlinear analysis of RC beam by taking into account the nonlinear effects into the simplifying moment-curvature relation. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed model to the nonlinear analysis of RC structures.

Generalized Lateral Load-Displacement Relationship of Reinforced Concrete Shear Walls (철근콘크리트 전단벽의 횡하중-횡변위 관계의 일반화)

  • Mun, Ju-Hyun;Yang, Keun-Hyeok
    • Journal of the Korea Concrete Institute
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    • v.26 no.2
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    • pp.159-169
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    • 2014
  • This study generalizes the lateral load-displacement relationship of reinforced concrete shear walls from the section analysis for moment-curvature response to straightforwardly evaluate the flexural capacity and ductility of such members. Moment and curvature at different selected points including the first flexural crack, yielding of tensile reinforcing bar, maximum strength, 80% of the maximum strength at descending branch, and fracture of tensile reinforcing bar are calculated based on the strain compatibility and equilibrium of internal forces. The strain at extreme compressive fiber to determine the curvature at the descending branch is formulated as a function of reduction factor of maximum stress of concrete and volumetric index of lateral reinforcement using the stress-strain model of confined concrete proposed by Razvi and Saatcioglu. The moment prediction models are simply formulated as a function of tensile reinforcement index, vertical reinforcement index, and axial load index from an extensive parametric study. Lateral displacement is calculated by using the moment area method of idealized curvature distribution along the wall height. The generalized lateral load-displacement relationship is in good agreement with test result, even at the descending branch after ultimate strength of shear walls.

Strength and Moment-Curvature Relationship of HCFT Columns under Eccentric Load (편심압축이 작용하는 HCFT기둥에 대한 내력특성과 모멘트-곡률의 곤계)

  • 이승조;박정민;김화중
    • Journal of the Korea Concrete Institute
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    • v.14 no.6
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    • pp.864-873
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    • 2002
  • Recently, CFT Column has reported a lot of study result, because a CFT column has certain superior structural properties as well as good productivity, execution efficiency, and improved rigidity over existing column. However, CFT column still has problems clearing the capacity evaluation between its steel tube member and high-strength concrete materials. Also, high-strength concrete filled steel square tube column(HCFT) examined numerical value explanatorily about transformation performance(M-ø) of when short-column receives equal flexure-moment from axial stress on research for concrete. hnd, with basis assumption, executed development of analysis program of moment-curvature relation for analytic analysis of transformation performance of HCFT section that get by an experiment. This study investigated to properties of structural(capacity, curvature), through a series of experiments for HCFT with key parameters, such as strength of concrete(600kgf/$\textrm{cm}^2$), D/t ratio, slenderness ratio(λ) and concrete kinds under eccentric load. And, I executed comparative analysis with AISC-LRFD, AIJ and Takanori Sato etc. and experiment result that is capacity design formula.

Equivalent Column Stiffness Equations for Design of RC Slender Columns under Later Loads (횡하중을 받는 철근콘크리트 장주설계를 위한 기둥의 등가강성식)

  • 이재훈
    • Magazine of the Korea Concrete Institute
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    • v.7 no.1
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    • pp.156-164
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    • 1995
  • P-${\Delta}$ analysis by use of the equivalent colurnn stiffness determined by Momcnt curvature-Thrust curves provides relatively precise analytical results for unbraced reinforced concrete columns, however it needs a complicated arialytical procedure. Equ~valent col~rnn stiffness equations are proposed for a simple analytical procedure which are ckterrnined by the Moment-Curvature Thrust curves of the practically useable sections. Thc proposed stiffness equations are appiled to P-${\Delta}$ analysis and rnornent magnifier method to compare with the selected test result. Use of the proposed stiffness equations may slrnplify the P-${\Delta}$ i.rialvtica1 procedure and improve the accuracy of moment magnifier niethod.

Nonlinear Moment-Curvature Relations and Numerical Structural Analysis of High-Strength PSC Flexural Members (고강도 PSC 휨부재의 비선형 모멘트-곡률 관계와 전산구조해석)

  • 연정흠;이제일
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.1
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    • pp.95-104
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    • 2002
  • A methods to calculate non-linear moment-curvature relations of high-strength PSC flexural members for numerical analysis has been proposed. The moment-curvature relations were calculated with assumptions of design codes and by the layer method. The results of the proposed procedures for moment-curvature relations and numerical analysis were compared with those of pre-existing tests. The absorption energy rate of the design codes was about 30% larger than that of the layer method. The ultimate load and the external work of the layer method were 90% and 85% of those of tests, respectively The ultimate load of the strength design method was 97% of that of tests, but the external work was over-estimated with 122%. The ultimate load and external work by the proposed equation of the CEB-FIP Model Code were 113% and 173% of those of tests, respectively. It show that the use of ultimate strain of 0.0035 should be over-estimated for high-strength concrete. The procedure of non-linear numerical analysis of this research could be stably simulated the behavior of concrete flexural members until the ultimate state, and calculate results of the load-deflection relation and cracking pattern were very similar with those of tests.

Evaluation on Moment-Curvature Relations and Curvature Ductility Factor of Reinforced Concrete Beams with High Strength Materials (고강도 재료를 사용한 철근콘크리트 보의 모멘트-곡률관계 및 곡률연성지수 평가)

  • Lee, Hyung-Joon
    • Journal of the Korea Concrete Institute
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    • v.25 no.3
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    • pp.283-294
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    • 2013
  • The high strength materials have been more widely used in reinforced concrete structures, specially, the reinforcing steel is permitted to used in RC structures up to yielding strength of 600 MPa. The strength of materials in RC beam section effects on the behavior and ductility of the RC members. In this study, the numerical analysis has been conducted to obtain the complete moment-curvature relation and the curvature ductility factor for the rectangular RC beams sections under the various reinforcement conditions and the effects of concrete strength, yield strength of reinforcement steel on the behavior and the curvature ductility factor of RC beam sections have been evaluated. The compressive strength of concrete and yield strength of steel have effected in various manner on the behavior and the curvature ductility factor of RC beam sections under reinforcement conditions. In the case of beam sections with equal resisting moment. the curvature ductility factor of RC beam section decreased with an increase in the yield strength of steel and increased with an increase in the concrete strength. When the yield strength of steel increased from 400 MPa to 600 MPa, the curvature ductility factor reduced about 30% and as the concrete strength increased from 30 MPa to 70 MPa, the curvature ductility factor of RC beam section increased about 3 times.

Equivalent Plastic Hinge Length Model for Flexure-Governed RC Shear Walls (휨 항복형 철근콘크리트 전단벽의 등가소성힌지길이 모델)

  • Mun, Ju-Hyun;Yang, Keun-Hyeok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.2
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    • pp.1-8
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    • 2014
  • The present study proposes a simple equation to straightforwardly determine the potential plastic hinge length in boundary element of reinforced concrete shear walls. From the idealized curvature distribution along the shear wall length, a basic formula was derived as a function of yielding moment, maximum moment, and additional moment owing to diagonal tensile crack. Yielding moment and maximum moment capacities of shear wall were calculated on the basis of compatability of strain and equilibrium equation of internal forces. The development of a diagonal tensile crack at web was examined from the shear transfer capacity of concrete specified in ACI 318-11 provision and then the additional moment was calculated using the truss mechanism along the crack proposed by Park and Paulay. The moment capacities were simplified from an extensive parametric study; as a result, the equivalent plastic hinge length of shear walls could be formulated using indices of longitudinal tensile reinforcement at the boundary element, vertical reinforcement at web, and applied axial load. The proposed equation predicted accurately the measured plastic hinge length, providing that the mean and standard deviation of ratios between predictions and experiments are 1.019 and 0.102, respectively.