• Title, Summary, Keyword: plastic hinge length

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An Experimental Study on the Flexural Stiffness and Plastic Hinge Ratation Capacity of Reinforced High Performance Concrete Beams (고성능 철근콘크리트 보의 휨강성 및 소성힌지의 회전능력에 관한 실험적 연구)

  • 고만영;김상우;김용부
    • Magazine of the Korea Concrete Institute
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    • v.10 no.4
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    • pp.93-100
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    • 1998
  • This paper presents a study on the flexural stiffness, plastic hinge length and plastic hinge rotation capacity of reinforced high performance concrete beams. 15 beams with different strength of concrete, reinforcement ratio and the pattern of loadings were tested. From the test results of reinforced normal strength concrete beams and reinforced high performance concrete beams with the concrete which has cylinder compressive strength of 700kg/${cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. It is found that an extreme fiber concrete compressive strain of ${\varepsilon}_{cu}=0.0047$ may be used in ultimate curvature computations of reinforced high performance concrete beams. An empirical equation is proposed to estimate the effective moment of inertia. length and rotation capacity of plastic hinge of simply supported reinforced high performance concrete beams. The estimated deflections using this equation agree well with the experimental values.

An Experimental Study on the Inelastic Rotation Capacity of Reinforced Concrete Beams with Lateral Reinforcement (횡방향보강근을 갖는 철근콘크리트보의 비탄성 회정능력에 관한 실험적 연구)

  • 연규원;이주나;강민철;윤정민;박찬수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.433-439
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    • 2000
  • Reinforced concrete beams show increased ductile behavior when the compressive concrete is confined with transverse steel. In the inelastic range, the most variations of ductile behaviour are defined the equivalent length of the plastic hinge and the plastic hinge rotation. In an investigation to study the influence of such confinement, sixteen reinforced concrete beams were tested in flexure and the deflections noted at all stages of loading. For all the beams tested, the plastic hinge rotation have been computed and the effect of confinement on the same examined. The conclusions are summarized as follows: The equivalent lengths of the plastic hinge are ranged within the effective depth comparatively. The ability of the plastic hinge rotation of the reinforced concrete beams confined with transverse steel are enlarged when transverse reinforcement content are increased, but the spaces are more important as the shear force are largely increased.

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Plastic Hinge Length of Reinforced Concrete Columns with Low Height-to-Width Ratio (전단경간비가 작은 철근콘크리트 기둥의 소성힌지 길이)

  • Park, Jong-Wook;Woo, Jae-Hyun;Kim, Byung-Il;Lee, Jung-Yoon
    • Journal of the Korea Concrete Institute
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    • v.22 no.5
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    • pp.675-684
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    • 2010
  • The reinforced concrete members are designed to fail in flexural to lead ductile fracture. In the building structures, the failure is typically imposed on beams to prevent damages in columns. However, progression of plastic collapse mechanism may ultimately develop, a plastic hinge at the bottem end of the first floor column, which then can be subjected to shear or bond finally due to large axial force and small shear span-to-depth ratio. In this study, 10 RC column specimens failed in shear after flexural yielding was investigated to determine the factors affecting the plastic hinge length. The findings of this study showed that the most effective factor affecting the plastic hinge length was an axial force. As an axial force increase, an axial strain and a ductility ratio were decreased obviously. The test also shows the observed plastic hinge length was about 0.8~1.2d and the this result has difference compared with forward research.

Analysis of Plastic Hinge of Pile-Bent Structure with Varying Pile Diameters (단일형 현장타설말뚝의 소성힌지를 고려한 최적설계법 제안)

  • Ahn, Sang-Yong;Jeong, Sang-Seom;Kim, Jae-Young
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.349-356
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    • 2010
  • In this study, a new design method of pile bent structure considering plastic hinge was proposed on the basis of the beam-column model. Based on the analysis results, it is found that the positioning of plastic hinge on the pile bent structure was influenced by nonlinear behavior of material and p-$\Delta$ effect. Moreover, concrete cracking began to occur at the joint section between the pile and column in case of pile bent structure with different cross-sections. The plastic hinge can be developed on the pile bent structure when large displacement was occurred, and pile bent structures can be maintained well only if it is developed on the column part. Therefore, in this study, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Based on this, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio($D_c/D_p$) and normalized lateral cracking load ratio($F/F_{Dc=Dp}$). And through this study, it is founded that in-depth limit($L_{As}$=0.4%) normalized by the pile length($L_P$) are proportionally decreased as the pile length($L_P/D_P$) increases up to $L_P/D_P$=17.5, and beyond that in-depth limit converges to a constant value. Finally, it is found that the proposed limit depth by taking into account the minimum concrete-steel ratio would be more economical design of the pile bent structure.

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Effects of Stressed and Unstressed Reinforcements on Prestressed Concrete Members with Unbonded Tendons

  • Moon, Jeong-Ho;Shin, Kyung-Jae;Lim, Jae-Hyung;Lee, Sun-Hwa
    • KCI Concrete Journal
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    • v.12 no.1
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    • pp.131-138
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    • 2000
  • The research purpose of this paper is to investigate the influential Parameters on the unbonded tendon stress. The parameters were the reinforcing ratio, the prestressing ratio, and the loading type. To this end. first, the influence of parameters were examined with twenty eight test results obtained from references. Then, an experimental study was carried out with nine specimens. Test variables were the reinforcing ratio and the prestressing ratio. Specimens were divided equally into three groups and each group had a different level of the reinforcing ratio. Each specimen within a group has a different level of the prestressing ratio. The investigation with previous and current tests revealed the followings; (1) the length of crack distribution zone does not have a close relation with the length of plastic hinge. (2) the prestressing ratio does not affect both the length of crack distribution and the length of plastic hinge, (3) the tendon stress variation is in reverse relation with the ratios of mild steels and tendons, (4) the loading type nay not affect significantly the length of crack distribution zone, (5) AASHTO LRFD Code equation and Moon/Lim's design equation predicted the test results well with some safety margins.

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Length of Plastic Hinge in RC Columns under Cyclic Loading (반복 하중을 받는 철근콘크리트 기둥의 소성힌지 길이)

  • Park, Jong-Wook;Choi, Im-Jun;Moon, Cho-Hwa;Lee, Jung-Yoon
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.11-12
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    • 2009
  • The small height to depth ratio column dominated by shear after tension steel yielded and the energy dissipation capacity reduce remarkably due to the affection of axial force. This procedure incur in the plastic hinge region and not in all of the region at the same time but from somewhere where the energy was concentrated. This study was reported about the variation of length of the plastic hinge under cyclic loading of the RC columns through the test.

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Experimental and numerical investigation of the seismic performance of railway piers with increasing longitudinal steel in plastic hinge area

  • Lu, Jinhua;Chen, Xingchong;Ding, Mingbo;Zhang, Xiyin;Liu, Zhengnan;Yuan, Hao
    • Earthquakes and Structures
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    • v.17 no.6
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    • pp.545-556
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    • 2019
  • Bridge piers with bending failure mode are seriously damaged only in the area of plastic hinge length in earthquakes. For this situation, a modified method for the layout of longitudinal reinforcement is presented, i.e., the number of longitudinal reinforcement is increased in the area of plastic hinge length at the bottom of piers. The quasi-static test of three scaled model piers is carried out to investigate the local longitudinal reinforcement at the bottom of the pier on the seismic performance of the pier. One of the piers is modified by increased longitudinal reinforcement at the bottom of the pier and the other two are comparative piers. The results show that the pier failure with increased longitudinal bars at the bottom is mainly concentrated at the bottom of the pier, and the vulnerable position does not transfer. The hysteretic loop curve of the pier is fuller. The bearing capacity and energy dissipation capacity is obviously improved. The bond-slip displacement between steel bar and concrete decreases slightly. The finite element simulations have been carried out by using ANSYS, and the results indicate that the seismic performance of piers with only increasing the number of steel bars (less than65%) in the plastic hinge zone can be basically equivalent to that of piers that the number of steel bars in all sections is the same as that in plastic hinge zone.

Cyclic load testing and numerical modeling of concrete columns with substandard seismic details

  • Marefat, Mohammad S.;Khanmohammadi, Mohammad;Bahrani, Mohammad K.;Goli, Ali
    • Computers and Concrete
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    • v.2 no.5
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    • pp.367-380
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    • 2005
  • Recent earthquakes have shown that many of existing buildings in Iran sustain heavy damage due to defective seismic details. To assess vulnerability of one common type of buildings, which consists of low rise framed concrete structures, three defective and three standard columns have been tested under reversed cyclic load. The substandard specimens suffered in average 37% loss of strength and 45% loss of energy dissipation capacity relative to standard specimens, and this was mainly due to less lateral and longitudinal reinforcement and insufficient sectional dimensions. A relationship has been developed to introduce variation of plastic length under increasing displacement amplitude. At ultimate state, the length of plastic hinge is almost equal to full depth of section. Using calibrated hysteresis models, the response of different specimens under two earthquakes has been analyzed. The analysis indicated that the ratio between displacement demand and capacity of standard specimens is about unity and that of deficient ones is about 1.7.

Evaluation of Plastic Rotational Capacity Based on Material Characteristics in Reinforced Concrete Flexural Members (재료 특성에 기반한 철근콘크리트 휨부재의 소성회전능력 산정)

  • Choi, Seung-Won;Kim, Woo
    • Journal of the Korea Concrete Institute
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    • v.22 no.6
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    • pp.825-832
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    • 2010
  • Although a critical section reaches its flexural strength in reinforced concrete structures, the structure does not always fail because moment redistribution occurs during the formation of plastic hinges. Inelastic deformation in a plastic hinge region results in plastic rotation. A plastic hinge mainly depends on material characteristics. In this study, a plastic hinge length and plastic rotation are evaluated using the flexural curvature distribution which is derived from the material models given in Eurocode 2. The influence on plastic capacity the limit values of the material model used, that is, ultimate strain of concrete and steel and hardening ratio of steel(k), are investigated. As results, it is appeared that a large ultimate strain of concrete and steel is resulting in large plastic capactiy and also as a hardening ratio of steel increases, the plastic rotation increases significantly. Therefore, a careful attention would be paid to determine the limit values of material characteristics in the RC structures.

Softening Analysis of Reinforced Concrete Frames (철근콘크리트 골조의 연성화 해석)

  • 나유성;홍성걸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.438-443
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    • 1998
  • Softening os the name used for decreasing bending moment at advanced flexural deformation. To accommodate softening deformation in analysis, it is assumed that a hinge has finite length. The softening analysis of R/C frames relies on the primary assumption that softening occurs over a finite hinge length and that the moment-curvature relationship for any section may be closely described by a trilinear approximation. A stiffness matrix for elastic element with softening regions are derived and the stiffness matrix allows extension of the capability of an existing computer program for elastic-plastic analysis to the softening situation. The effect of softening on the collapse load of R/C frame is evaluated.

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