• Title, Summary, Keyword: plastic hinge length

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Seismic Performance Assessment of Existing Circular Sectional RC Bridge Columns according to Lap-splice Length of Longitudinal Bars (축방향철근의 겹침이음길이에 따른 원형 RC교각의 내진성능평가)

  • Park, Kwang Soon;Seo, Hyeong Yeol;Kim, Tae-Hoon;Kim, Ick Hyun;Sun, Chang Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.18 no.4
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    • pp.201-212
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    • 2014
  • The plastic hinge region of RC pier ensures its nonlinear behavior during strong earthquake events. It is assumed that the piers secure sufficient strength and ductility in order to prevent the collapse of the bridge during strong earthquake. However, the presence of a lap-splice of longitudinal bars in the plastic hinge region may lead to the occurrence of early bond failure in the lap-splice zone and result in significant loss of the seismic performance. The current regulations for seismic performance evaluation limit the ultimate strain and displacement ductility considering the eventual presence of lap-splice, but do not consider the lap-splice length. In this study, seismic performance test and analysis are performed according to the cross-sectional size and the lap-splice length in the case of longitudinal bars with lap-splice located in the plastic hinge region of existing RC bridge columns with circular cross-section. The seismic behavioral characteristics of the piers are also analyzed. Based upon the results, this paper presents a more reasonable seismic performance evaluation method considering the lap-splice length and the cross-sectional size of the column.

The Discrete Optimum Design of Steel Frame Considering Material and Geometrical Nonlinearties (재료 및 기하학적 비선형을 고려한 브레이싱된 강뼈대구조물의 최적설계)

  • Chang, Chun Ho;Park, Moon Ho;Lee, Hae Kyoung;Park, Soon Eung
    • Journal of Korean Society of Steel Construction
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    • v.12 no.3
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    • pp.317-328
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    • 2000
  • The objective of the research is to develop an algorithm for the optimum design of two-dimensional braced steel frames using an advanced analysis, which considers both material and geometric nonlinearties. Since both nonlinearties are considered in analysis process, Optimum design algorithm which does not require to calculate K-factor is presented. A multi-level discrete optimization technique with two parameters that uses the information of structural system and separate member has been developed. The structural analysis is performed by the relined plastic-hinge method which is based on zero-length plastic hinge theory. Optimization problem are formulated by AISC-LRFD code. The feasibility, validity and efficiency of the developed algorithm is demonstrated by the results of the braced steel frame.

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3-D Frame Design Using Second-Order Plastic-Hinge Analysis Accounting for Lateral Torsional Buckling (횡비틀림좌굴을 고려하는 2차 소성힌지해석을 이용한 3차원 강뼈대 구조물 설케)

  • 김승억;박주수
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.1
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    • pp.117-126
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    • 2002
  • In this paper, 3-D fame design using second-orders plastic-hinge analysis accounting for lateral torsional buckling is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional second-order plastic-hinge analyses, which do not consider the degradation of the flexural strength caused by lateral torsional buckling, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, second-order effect, and geometric imperfections are presented. In this study, a model consisting of the unbraced length and cross-section shape is used to account for lateral torsional buckling. The proposed analysis is verified by the comparison of the LRFD results. A case studs shows that lateral torsional buckling is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient reliable tool ready to be implemented into design practice.

Material Nonlinear Analysis of RC Beams (철근 콘크리트 보의 재료비선형 해석)

  • 곽효경;김지은
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.133-140
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    • 1998
  • Material nonlinear analyses of RC(Reinforced Concrete) beams considering the tension stiffening effect and plastic hinge length have been conducted. Instead of taking the sophisticated layer approach which has some limitations in application to the large structures with many degrees of freedom. the moment-curvature relationships of RC sections previously constructed through the section analysis have been used. To reduce the numerical instability in nonlinear analysis and to remove the imprecision in calculation of ultimate resisting capacity, according to the used finite element mesh size, the tension stiffening effect and plastic hinge length have been taken into consideration. Finally, correlation studies between analytical and experimental results have been conducted with the objective to establish the validity of the proposed algorithms.

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Comparison of displacement capacity of reinforced concrete columns with seismic codes

  • Cansiz, Sinan;Aydemir, Cem;Arslan, Guray
    • Advances in concrete construction
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    • v.8 no.4
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    • pp.295-304
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    • 2019
  • The lateral displacement or drift may be the cause of the damage in the reinforced concrete (RC) columns under the seismic load. In many regulations, lateral displacement was limited according to the properties of columns. The design displacement limits may be represented indirectly through the material strain limits and the mechanical properties of columns. EUROCODE-8 and FEMA356 calculate displacement limits by taking into account the mechanical properties of columns. However, Turkey Building Earthquake Code (TBEC) determine displacement limits by taking into account the material strain limits. The aim of this study is to assess the seismic design codes for RC columns through an experimental study. The estimates of seismic design codes have been compared with the experimental results. It is observed that the lateral displacement capacities of columns estimated according to some seismic codes are not in agreement with the experimental results. Also, it is observed that TBEC is conservative in the context of the performance indicator of RC columns, compared to EUROCODE-8 and FEMA356. Moreover, in this study, plastic hinge length and effective stiffness of test elements were investigated.

Yield penetration in seismically loaded anchorages: effects on member deformation capacity

  • Tastani, S.P.;Pantazopoulou, S.J.
    • Earthquakes and Structures
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    • v.5 no.5
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    • pp.527-552
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    • 2013
  • Development of flexural yielding and large rotation ductilities in the plastic hinge zones of frame members is synonymous with the spread of bar reinforcement yielding into the supporting anchorage. Yield penetration where it occurs, destroys interfacial bond between bar and concrete and reduces the strain development capacity of the reinforcement. This affects the plastic rotation capacity of the member by increasing the contribution of bar pullout. A side effect is increased strains in the compression zone within the plastic hinge region, which may be critical in displacement-based detailing procedures that are linked to concrete strains (e.g. in structural walls). To quantify the effects of yield penetration from first principles, closed form solutions of the field equations of bond over the anchorage are derived, considering bond plastification, cover debonding after bar yielding and spread of inelasticity in the anchorage. Strain development capacity is shown to be a totally different entity from stress development capacity and, in the framework of performance based design, bar slip and the length of debonding are calculated as functions of the bar strain at the loaded-end, to be used in calculations of pullout rotation at monolithic member connections. Analytical results are explored parametrically to lead to design charts for practical use of the paper's findings but also to identify the implications of the phenomena studied on the detailing requirements in the plastic hinge regions of flexural members including post-earthquake retrofits.

Research of Residual Strain Calculation of Prestressed Concrete Beam Element (프리스트레스트 콘크리트 보 부재의 잔류변형 산정에 대한 연구)

  • Lee, Duck-Ki
    • Journal of the Korea Concrete Institute
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    • v.26 no.4
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    • pp.555-562
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    • 2014
  • To perform performance-based seismic design of buildings, it is necessary clear goal for usage and stability after an earthquake. To clear this goal, it requires a review of the constituent material of the building and, in particular, a member used as an indicator of the residual strain is useful. There are more usage of prestressed concrete because of prestressing steel witch has characteristics of the origin-oriented. In this study, the goal is estimating of residual strain on the prestressed concrete beam member. The expression for angle of deformed prestressed concrete beam member was obtained from using of curvature on the critical section and the equivalent plastic hinge length based on 'equivalent plastic hinge length method'. Considering the balance of strength and deformation conditions, suitable analysis values were derived from 'split Element Method'. Through various parametric studies, various factors affecting the residual strain were decided. Based on the results of this study, it is expected many researches will be proceed in the future.

Flexural Behavior of Concrete-ECC Composite Beam Reinforced with Steel Rebar (철근 보강된 콘크리트-ECC 복합보의 휨 거동)

  • Hyun, Jung-Hwan;Bang, Jin-Wook;Lee, Bang-Yeon;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.3
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    • pp.104-111
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    • 2020
  • The purpose of this study is to investigate the flexural behavior and plastic hinge of reinforced concrete-ECC composite beams. Ordinary portland cement was used as a binder, and high volume fly ash was also used to improve the properties of ECC. An ECC designed in this study showed high tensile strain capacity of 3.0%. Three types of beams were manufactured according to the replacement length of concrete with ECC. From the bending tests, it was found that load-bearing capacity as well as ductility of beam increased with an increase in the replacement length of concrete with ECC. Curvature ductility and plastic hinge length of beam were also increased.

Seismic Curvature Ductility of RC Bridge Piers with 2.5 Aspect Ratio (형상비 2.5의 RC 교각의 내진 곡률연성도)

  • Chung, Young-Soo;Park, Chang-Kyu;Lee, Eun-Hee
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.3
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    • pp.1-12
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    • 2004
  • Due to the 1989 Loma Prieta, 1995 Hyogoken Nambu earthquakes, etc, a number of bridge columns  were collapsed in flexure-shear failures as a consequence of the premature termination of the column longitudinal reinforcement. Nevertheless, previous researches for the performance of bridge columns were concentrated on the flexural failure mode. It is well understood that the seismic behaviour of RC bridge piers was dependent on the performance of the plastic hinge of RC bridge piers, the ductility of which was desirable to be computed on the basis of the curvature. Experimental investigation was made to evaluate the variation of the curvature of the plastic hinge  region for the seismic performance of earthquake-damaged RC columns in flexure-shear failure mode. Seven test specimens in the aspect ratio of 2.5 were made with test parameters: confinement ratios, lap splices, and retrofitting FRP materials. They were damaged under series of artificial earthquakes that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading under a constant axial load, $P=0.1f_{ck}A_g$. Residual seismic capacity of damaged specimens was evaluated by analzying the moment-curvature hysteresis and the curvature ductility. Test results show that the biggest curvature was developed around 15cm above the footing, which induced the column failure. It was observed that RC bridge specimens with lap-spliced longitudinal steels appeared to fail at low curvature ductility but significant improvement was made in the curvature ductility of RC specimens with FRP straps wrapped around the plastic hinge region. Based on the experimental variation of the curvature of RC specimens, new equivalent length of the plastic hinge region was proposed by considering the lateral confinement in this study. The analytical and experimental relationship between the displacement and the curvature ductility were compared based on this proposal, which gave excellent result.

Design of Steel Frames using Plastic Hinge Analysis (소성힌지해석을 이용한 강골조 시스템의 설계)

  • Chang, Chun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.3
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    • pp.131-140
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    • 2004
  • The main objective of the research is to develop an algorithm for the optimum design of two dimensional steel frames using refined plastic hinge analysis which considers material and geometrical nonlinearities. Using developed algorithm, an optimum design was perform without calculating an effective length factor of the column (K-factor). A multi-level discrete optimization technique with two parameters has been developed and employed in the optimum design algorithm. The optimization algorithm is applied to structural design with the objective of minimizing the weight of a structure and with constraints on load limit, frame drift, ductility. Various application example is provided to demonstrate the feasibility, validity and efficiency of the developed program.