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

Marefat, Mohammad Sadegh; Khanmohammadi, Mohammadreza; Bahrani, Mohammad Kazem; Goli, A.

doi:10.12989/cac.2005.2.5.367

Cited by 13 publications

(5 citation statements)

References 8 publications

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“…These theoretical strengths include M ACI based on ACI Code, M EC based on Eurocode 2 and M NZ based on the New Zealand Code. The comparison is summarised in Tables 6-9 for, respectively, RC columns subjected to a low axial load level (0 < P/A g f ′ c ≤ 0.2) [12,14,27,29,51,52]; a medium axial load level (0.2 < P/A g f ′ c ≤ 0.5) [12-14,51-54]; a high axial load level (0.5 < P/A g f ′ c ≤ 0.7) [11,13,55,56]; and an ultra-high axial load level (0.7 < P/A g f ′ c ) [11,52,53,55,57].…”

Section: Verification Against Experimental Resultsmentioning

confidence: 99%

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Strain gradient effects on flexural strength design of normal-strength concrete columns

Ho¹,

Peng²

2011

Engineering Structures

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a b s t r a c tThe equivalent rectangular concrete stress block has commonly been adopted for the flexural strength design of reinforced concrete (RC) members for decades. In this stress block, the equivalent concrete stress is expressed as αf ′ c (f ′ c is the uni-axial concrete cylinder strength). Currently, the value of α adopted in various RC design codes is only concrete-strength dependent and equal to 0.85 for NSC. However, in an experimental study conducted previously by the authors on NSC columns subjected to concentric and eccentric axial loads, it was found that α increases significantly as the strain gradient increases. Therefore, the effect of the strain gradient should not be neglected. In this paper, a review on the previous test results on NSC columns is presented and a strain-gradient dependent equivalent rectangular concrete stress block is developed. Based on this proposed stress block, a new flexural strength design method for NSC columns that incorporates the effects of the strain gradient is proposed. A series of column interaction diagrams with various concrete strengths and steel ratios are derived for design purposes. Lastly, these interaction diagrams are compared with the existing column design charts provided in various RC design codes to verify their applicability.

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Section: Verification Against Experimental Resultsmentioning

confidence: 99%

“…The accuracy of the equivalent rectangular stress block adopted in some of the current RC design codes is investigated by comparing the flexural strength of NSC columns predicted by these codes with that measured by other researchers experimentally [11][12][13][14]. The flexural strength comparison is shown in Table 2.…”

Section: Introductionmentioning

confidence: 99%

Strain gradient effects on flexural strength design of normal-strength concrete columns

Ho¹,

Peng²

2011

Engineering Structures

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“…2; A g is the column cross-section area) (Ho and Pam, 2003a;Marefat et al, 2005;Mo and Wang, 2000;Tao and Yu, 2008;Watson and Park, 1994;Woods et al, 2007) (c) columns subjected to medium axial load level (0 . 2 , P/A g f 9 c < 0 .…”

Section: Derivation Of Equivalent Rectangular Concrete Stress Block Pmentioning

confidence: 99%

“…2 , P/A g f 9 c < 0 . 5) (Lam et al, 2003;Marefat et al, 2005Marefat et al, , 2006Mo and Wang, 2000;Sheikh and Khoury, 1993;Tao and Yu, 2008;Watson and Park, 1994) (d ) columns subjected to high axial load level (0 . 5 , P/A g f 9 c < 0 .…”

Section: Derivation Of Equivalent Rectangular Concrete Stress Block Pmentioning

confidence: 99%

Equivalent stress block for normal-strength concrete incorporating strain gradient effect

Peng

Pam

et al. 2012

Magazine of Concrete Research

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To account for the different behaviours of concrete under uniaxial compression and bending in the flexural strength design of reinforced concrete (RC) members, the stress-strain curve of concrete is normally scaled down so that the adopted maximum concrete stress in flexural members is less than the uniaxial strength. However, it was found from previous experimental research that the use of a smaller maximum concrete stress would underestimate the flexural strength of RC beams and columns. To investigate the effect of strain gradient on the maximum concrete stress developed in flexure, a total of 12 plain concrete and RC inverted T-shaped specimens were fabricated and tested under concentric and eccentric loads separately. The maximum concrete stress developed in the eccentric specimens was determined by modifying the concrete stress-strain curve obtained from the counterpart concentric specimens based on axial force and moment equilibriums. The test results revealed that the maximum concrete stress increases with strain gradient up to a certain maximum value. A formula was developed to correlate the maximum concrete stress to strain gradient. A pair of equivalent rectangular concrete stress block parameters that incorporate the effects of strain gradient was proposed for flexural strength design of RC members.

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“…Pampanin, Christopoulos, and Priestley (2003), Zhou (2009) and Li, Samali, Ye, and Bakoss (2003) presented the observations from experimental investigations on the behaviour of RC beam -column connections strengthened by using hybrid FRP reinforcement under static loading. Marefat, Kanmohammad, and Goli (2005) investigated the hysteretic response of substandard RC columns under reverse cyclic loading, and the responses were compared with the columns designed based on ACI318. Performance evaluation and strengthening of deficient beam -column sub-assemblages under cyclic loading was conducted by Sasmal (2009).…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of performance of near-surface mounted FRP-upgraded beam–column sub-assemblages under cyclic loading

Sasmal

Khatri

Ramanjaneyulu

2014

Structure and Infrastructure Engineering

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This study deals with the performance of the upgrading schemes for the existing gravity load designed (GLD) reinforced concrete (RC) beam -column sub-assemblages using near-surface mounted (NSM) fibre-reinforced polymer (FRP) bars. In this study, exterior beam -column sub-assemblage of a general RC-framed structure has been considered. Numerical investigations of the sub-assemblages have been carried out under cyclic loading using nonlinear finite element analysis. Experimentally validated numerical models have been used for evaluating the performance of various upgrading schemes using NSM bars. Cyclic behaviour of reinforcement, concrete modelling based on fracture energy, bond-slip relations between concrete and steel reinforcement have been incorporated. The study also includes numerical investigation of crack and failure patterns, ultimate load-carrying capacity, strain comparisons and formation of plastic hinges, load-displacement hysteresis, energy dissipation and ductility. Seismic performance in terms of energy dissipation and development of strain in beam bar shows that some of the upgraded schemes are found to be comparable to the seismically designed ductile specimens. The findings of this study would be helpful to the practising and design engineers for developing detailing criteria for newly designed -or strengthening of deficient -reinforced concrete structure.

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

Cited by 13 publications

References 8 publications

Strain gradient effects on flexural strength design of normal-strength concrete columns

Strain gradient effects on flexural strength design of normal-strength concrete columns

Equivalent stress block for normal-strength concrete incorporating strain gradient effect

Numerical simulation of performance of near-surface mounted FRP-upgraded beam–column sub-assemblages under cyclic loading

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