Strength and ductility of laterally confined concrete columns

Chung, Heon-Soo; Yang, Keun–Hyeok; Lee, Young-Ho; Eun, Hee-Chang

doi:10.1139/l02-084

Cited by 34 publications

(24 citation statements)

References 12 publications

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“…For the same volume ratio of wire ropes, the smaller the diameter and the closer the spacing of wire ropes, the higher the strength gain factor and ductility ratio, similar to the case of tied columns. 10 The prestress applied to wire ropes had little influence on the strength gain factor but the ductility ratio decreased with the increase of the prestress in wire ropes as earlier rupture of wire ropes occurred. The measured upper bound for strength gain factor of strengthened core concrete except speci- Yang and Ashour mens C7 and C11 having wire rope spacing larger than D c =2 was more than 1 .…”

Section: General Behaviourmentioning

confidence: 93%

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Tests of reinforced concrete short columns laterally strengthened with wire rope units and steel elements

Yang

Ashour

2007

Magazine of Concrete Research

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The current paper presents a simple unbonded-type column strengthening technique with wire rope units and few steel elements. Eleven short columns were strengthened using the proposed procedure and tested under monotonic concentric axial loads. The main variables investigated to evaluate the confinement effectiveness of strengthened concrete columns were the volume ratio, prestress, diameter, spacing and configuration of wire rope units. The strength gain factor and ductility ratio increased with the increase of volume ratio of wire ropes. The prestress applied to wire ropes had little influence on the strength gain factor but the ductility ratio decreased with the increase of prestress in the wire ropes, owing to earlier rupture of wire ropes. At the same volume ratio of wire ropes, the maximum strength of columns was nearly independent on the configuration of the wire ropes, but higher ductility was exhibited by columns strengthened with rectangular spiral-type wire ropes than by columns strengthened with hoop-type wire ropes, until rupture of the wire ropes. The strength gain factor and ductility ratio of strengthened columns were compared with those of tied columns tested in a previous study. The load capacity of strengthened columns was also predicted using the ACI 318-05 equation modified to reflect the load-carrying effect of steel elements. A much higher strength gain factor and ductility ratio were exhibited by strengthened columns than tied columns having the same lateral reinforcement, except for strengthened columns with wire rope spacing above 0 . 5 times core width. The axial load capacity of strengthened columns was higher than that of unstrengthened columns by 5-20%, and could be reasonably predicted using the modified ACI 318-05 equation.

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Section: General Behaviourmentioning

confidence: 93%

“…The strength gain factor [1][2][3][4][5][6][7]10 and ductility ratio 3,4 of columns tested can be defined as follows…”

Section: General Behaviourmentioning

confidence: 99%

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Tests of reinforced concrete short columns laterally strengthened with wire rope units and steel elements

Yang

Ashour

2007

Magazine of Concrete Research

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“…To consider the strain rate sensitivity of concrete, the dynamic compressive cylinder strength fcd of concrete can be estimated from Equations 1 and 2 provided by CEB-FIP Model Code 1990 [1]. where fcs is the quasi-static compressive strength of unconfined concrete; fcs=0.85fc considering a strength-reduction factor related to the column shape, size and the difference between the strength of in situ concrete and the strength determined from standard cylinder tests [22][23];  is the strain rate (s -1 ); fc0=10 Mpa; and cs  =30×10 -6 s -1 . fcd increases with increasing strain rate; the other parameters in the following uniaxial compressive stress-strain curve correspondingly change, and the dynamic uniaxial compressive stress-strain curve is formed.…”

Section: Fig 2 -Illustration Of the Finite Element Modelmentioning

confidence: 99%

Finite Element Analysis of the Behaviour of Reinforced Concrete Columns Confined by Overlapping Hoops Subjected to Rapid Concentric Loading

Zeng¹

2017

CEJ

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The strain rate sensitivity of concrete material was discovered approximately one hundred years ago, and it has a marked effect on the behaviour of concrete members subjected to dynamic loadings such as strong earthquake and impact loading. Because of the great importance of the confined reinforced concrete (RC) columns in RC structures, the dynamic behaviour of the columns induced by the strain rate effect has been studied, but only few experiments and analyses have been conducted. To investigate the behaviour of overlapping hoop-confined square reinforced normal-strength concrete columns, considering the strain rate effect at a strain rate of 10 -5 /sec to 10 -1 /sec induced by earthquake excitation, an explicit dynamic finite element analysis (FEA) model was developed in ABAQUS to predict the behaviour of confined RC columns subjected to the rapid concentric loading. A locally modified stress-strain relation of confined concrete with the strain rate sensitivity of the concrete material and the confining effect of overlapping hoops were proposed to complete the simulation of the dynamic behaviour of concrete with the concrete plastic-constitutive model in ABAQUS. The finite element predictions are consistent with the existing test results. Based on the FEA model, a parametric investigation was conducted to capture more information about the behaviour of confined RC columns under varying loading rates.

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“…Many researchers 10,12,13 pointed out that most of high-strength hoop reinforcement did not yield at the peak stress of concrete in tied columns. Sakino and Sun 13 limited the stress of hoop reinforcement at the peak stress of concrete below 700 MPa.…”

Section: Stress-strain Model Of Confined Concretementioning

confidence: 99%

Axial behaviour of reinforced concrete short columns strengthened with wire rope and T-shaped steel plate units

Yang¹,

Ashour²,

Lee³

2009

Magazine of Concrete Research

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This paper presents a relatively simple column strengthening procedure using unbonded wire rope and T-shaped steel plate units. Twelve strengthened columns and an unstrengthened control column were tested to failure under concentric axial load to explore the significance and shortcomings of the proposed strengthening technique. The main variables investigated were the volume ratio of wire ropes as well as geometrical size and configuration of T-shaped steel plates. Axial load capacity and ductility ratio of columns tested were compared with predictions obtained from the equation specified in ACI 318-05 and models developed for conventionally tied columns, respectively. The measured axial load capacities of all strengthened columns were higher than predictions obtained from ACI 318-05, indicating that the ratio of the measured and predicted values increased with the increase of volume ratio of wire ropes and flange width of T-shaped steel plates. In addition, at the same lateral reinforcement index, a much higher ductility ratio was exhibited by strengthened columns having a volume ratio of wire ropes above 0·0039 than tied columns. The ductility ratio of strengthened columns tested increased with the increase of flange width, thickness, and web height of T-shaped steel plates. A mathematical model for the prediction of stress–strain characteristics of confined concrete using the proposed strengthening technique is developed, that was in good agreement with test results.

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Strength and ductility of laterally confined concrete columns

Cited by 34 publications

References 12 publications

Tests of reinforced concrete short columns laterally strengthened with wire rope units and steel elements

Tests of reinforced concrete short columns laterally strengthened with wire rope units and steel elements

Finite Element Analysis of the Behaviour of Reinforced Concrete Columns Confined by Overlapping Hoops Subjected to Rapid Concentric Loading

Axial behaviour of reinforced concrete short columns strengthened with wire rope and T-shaped steel plate units

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