• Title, Summary, Keyword: Lateral confining effect

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Lateral confining action of mortar-filled sleeve reinforcement splice

  • Kim, Hyong-Kee;Lee, Sang-Ho
    • Structural Engineering and Mechanics
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    • v.41 no.3
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    • pp.379-393
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    • 2012
  • Of the various methods of splicing reinforcing bar in reinforced concrete structure, mortar-filled sleeve reinforcement splice offers diverse benefits, not only in terms of structural performance but also for the construction process. Consequently, after the mortar-filled sleeve splices have been developed in recent years, research and development on these splices has been actively carried out, in order to evaluate its macro structural performance, such as its strength and stiffness, with the aim of enabling this system to be applied to construction in the field as early as possible. However, to make a proper evaluation on the overall structural performance of the mortar-filled sleeve reinforcing bar splice, it is of critical importance to understand the lateral confining action of the sleeve, which is known to affect the bond strength between the embedded bar and mortar in the sleeve. Accordingly, in this study, an experiment of monotonic loading and cyclic loading was conducted with a full-sized mortar-filled sleeve splice attaching strain gauges on the sleeve surface with experimental variables such as development length of bar, etc. Based on the test results, the effect of the lateral confining action of the sleeve was analyzed and considered in terms of the bond strength between the bar and mortar in this splice.

Frictional effects on the cyclic response of laterally loaded timber fasteners

  • Allotey, Nii;Foschi, Ricardo
    • Structural Engineering and Mechanics
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    • v.21 no.1
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    • pp.1-18
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    • 2005
  • Foschi's connector model is used as a basic component in the development of nonlinear analysis programs for timber structures. This paper presents the extension of the model to include the effect of shaft frictional forces. The wood medium is modeled using the Foschi embedment model, while shaft friction is modeled using an elastic Coulomb-type friction model. The initial confining pressure for the case of driven fasteners is accounted for by a lateral shift of the load-embedment curve. The model is used to compute the cyclic response of both driven and inserted fasteners. The results obtained from the cases studied indicate that initial confining pressure and friction do not have a significant effect on the computed hysteretic response, however, they significantly affect the computed amount of fastener withdrawal. This model is particularly well-suited for modeling the hysteretic response of shear walls with moderate fastener withdrawal under lateral cyclic or earthquake loading.

Nonlinear Analysis of a Circular CFT Column Considering Confining Effects (구속 효과를 고려한 원형 CFT 기둥의 비선형 해석)

  • Han, Taek-Hee;Won, Deok-Hee;Yi, Gyu-Sei;Kang, Young-Jong
    • Journal of Korean Society of Hazard Mitigation
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    • v.9 no.6
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    • pp.1-9
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    • 2009
  • An analysis program to predict the behavior of a concrete filled steel tube column (CFT) was developed. It considered confining effect, material nonlinearity, strain hardening of steel, and initial axial load. With the developed program, axial load-bending moment interaction analyses, moment-lateral displacement relation analyses, and lateral load-lateral displacement relation analyses were performed. For the verification of the developed program, analysis results were compared with the test results from the other researches. The verified results showed that the developed program predicted the behavior of the CFT column with agreeable accuracy. And they showed that it is necessary to consider the confining effect for the reasonable analysis of the CFT column. A simple parametric study was performed and it chose the strength of unconfined concrete and the thickness of a steel tube as the major parameters affecting the behavior of the CFT column. The parametric analysis results showed that the CFT column had higher strength and smaller ductility by increasing the strength of concrete. But the CFT column showed higher strength and larger ductility by increasing the thickness of the steel tube.

Effectiveness of different confining configurations of FRP jackets for concrete columns

  • Moretti, Marina L.
    • Structural Engineering and Mechanics
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    • v.72 no.2
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    • pp.155-168
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    • 2019
  • This paper presents the results of an experimental investigation on the compressive strength of small scale concentrically axially loaded fiber-reinforced polymer (FRP) confined plain concrete columns, with cylinder concrete strength 19 MPa. For columns with circular (150-mm diameter) and square (150-mm side) cross sections wrapped with glass- and carbon-FRP sheets (GFRP and CFRP, respectively) applied with dry lay-up the effect of different jacket schemes and different overlap configurations on the confined characteristics is investigated. Test results indicate that the most cost effective jacket configuration among those tested is for one layer of CFRP, for both types of sections. In square sections the location of the lap length, either in the corner or along the side, does not seem to affect the confined performance. Furthermore, in circular sections, the presence of an extra wrap with FRP fibers parallel to the column's axis enhances the concrete strength proportionally to the axial rigidity of the FRP jacket. The recorded strains and the distributions of lateral confining pressures are discussed. Existing design equations are used to assess the lateral confining stresses and the confined concrete strength making use of the measured hoop strains.

Strength model for square concrete columns confined by external CFRP sheets

  • Benzaid, Riad;Mesbah, Habib Abdelhak
    • Structural Engineering and Mechanics
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    • v.46 no.1
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    • pp.111-135
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    • 2013
  • An experimental study has been carried out on square plain concrete (PC) and reinforced concrete (RC) columns strengthened with carbon fiber-reinforced polymer (CFRP) sheets. A total of 78 specimens were loaded to failure in axial compression and investigated in both axial and transverse directions. Slenderness of the columns, number of wrap layers and concrete strength were the test parameters. Compressive stress, axial and hoop strains were recorded to evaluate the stress-strain relationship, ultimate strength and ductility of the specimens. Results clearly demonstrate that composite wrapping can enhance the structural performance of square columns in terms of both maximum strength and ductility. On the basis of the effective lateral confining pressure of composite jacket and the effective FRP strain coefficient, new peak stress equations were proposed to predict the axial strength and corresponding strain of FRP-confined square concrete columns. This model incorporates the effect of the effective circumferential FRP failure strain and the effect of the effective lateral confining pressure. The results show that the predictions of the model agree well with the test data.

Development of Design Method of Compression(SSC) Anchor (압축헝 앵커의 설계법 개발)

  • 임종철;홍석우;이태형;이외득
    • Journal of the Korean Geotechnical Society
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    • v.15 no.1
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    • pp.63-78
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    • 1999
  • For the design of compression anchor, three things should be considered. The first is a resistance force by skin friction, the second is a tension strength of tendon, and the third is a compressive strength of grout. Especially, compressive strength of grout is the most important design parameter of compression anchor. When compression anchor is pulled out from the ground, the compressive strength of grout increases by confining pressure of ground($\sigma_{tg$). Here, $\sigma_{tg$ is the confining pressure which is produced by earth pressure at rest and by lateral expansion of grout. We call this phenomenon of increase of confining pressure "poisson effect". In this paper, the design method of compression anchor called SSC anchor and the computer program for the design are developed through compression tests of anchor body grout.ody grout.

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Experimental Study of Structural Capacity Evaluation of RC T-shape Walls with the Confinement Effect (단부구속 효과에 따른 철근콘크리트 T형 벽체의 구조성능 평가에 관한 실험적 연구)

  • 하상수;윤현도;최창식;오영훈;이원호;이리형
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.191-196
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    • 2001
  • The structural performance of a shear wall subjected to lateral loads is influenced by many factors, such as sectional shape, aspect ratio, vertical and horizontal reinforcement, lateral confinement and axial compression, etc. This experimental research is focusing to investigate the structural performance of T-shaped walls with different confining reinforcement. Experimental results show that all specimens finally failed by the crushing of the concrete in the compression zone. Although the location and content of the lateral confinement is different, the results are very similar during the negative loading direction where the flange is compressed. However, when flange is subjected to tension, the location and content of the lateral confinement results in a large difference in the structural performance of T-shaped walls. Therefore, selection of location and content of the lateral confinement would be important aspect in the design of the nonsymmetric structural walls.

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The ROP mechanism study in hard formation drilling using local impact method

  • Liu, Weiji;Zhu, Xiaohua;Zhou, Yunlai;Mei, Liu;Meng, Xiannan;Jiang, Cheng
    • Structural Engineering and Mechanics
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    • v.68 no.1
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    • pp.95-101
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    • 2018
  • The low rate of penetration and short lifetime of drilling bit served as the most common problems encountered in hard formation drilling, thus leading to severe restriction of drilling efficiency in oil and gas reservoir. This study developed a new local impact drilling method to enhance hard formation drilling efficiency. The limitation length formulas of radial/lateral cracks under static indentation and dynamic impact are derived based on the experimental research of Marshall D.B considering the mud column pressure and confining pressure. The local impact rock breaking simulation model is conducted to investigate its ROP raising effect. The results demonstrate that the length of radial/lateral cracks will increase as the decrease of mud pressure and confining pressure, and the local impact can result in a damage zone round the impact crater which helps the rock cutting, thus leading to the ROP increase. The numerical results also demonstrate the advantages of local impact method for raising ROP and the vibration reduction of bit in hard formation drilling. This study has shown that the local impact method can help raising the ROP and vibration reduction of bit, and it may be applied in drilling engineering.

Nonlinear Analysis considered Confinement Effect of Precast Concrete Segment (프리캐스트 콘크리트 세그먼트의 구속효과를 고려한 비선형 해석)

  • Lee, Heon-Min;Kim, Tae-Hoon;Park, Jae-Keun;Kim, Young-Jin;Shin, Hyun-Mock
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.305-308
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    • 2008
  • The purpose of this study is to propose the confinement effectiveness of precast segmental concrete that binding by lateral confining steel in the method of precast segmental concrete pridge piers construction. Generally, the confinement effect of concrete that binding by lateral confining steel is defined by the confinement effectiveness coefficient and the confinement effectiveness coefficient is defined as the ratio of area of effectively confined concrete core to area of confined concrete core. The area of effectively confined concrete core is defined by Arching action occurred on a space of lateral confinement steel and The area of confined concrete core is defined by the ratio of area of longitudinal reinforcement to area of core of section. But in case of precast segmental concrete, concrete cover that exist on top and bottom of concrete segment should be considered.

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Three-Dimensional Nonlinear Analysis of Reinforced Concrete Beam with Shear Reinforcements (전단보강된 철근 콘크리트 보의 3차원 거동해석)

  • 주영태;정헌주;이용학
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.431-436
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    • 2001
  • Lateral confining effect due to the existence of the shear reinforcements in R.C. beam is investigate in a numerical way. For the purpose, a three dimensional constitutive model of concrete is developed based on the elasto-plasticity using non-associated plastic flow rule to control the excessive inelastic dilatancy. The plastic flow direction is determined based on the associated plastic flow direction in a way to adjust the directional angle between the two normal vector components along the hydrostatic and deviatoric axis in a meridian plane in which the loading function prescribed. The current formulation is combined with the four parameter elasto-plastic triaxial concrete model recently developed. The resulting elasto-plastic triaxial concrete model predicts the fundamental behaviors of concrete under different confining levels and the 4-points flexural test of a beam with shear reinforcements, compares with the experimental results.

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