Deformability evaluation of high-strength reinforced concrete columns

Ho, J.C.M.; Pam, H. J.

doi:10.1680/macr.2010.62.8.569

Cited by 21 publications

(7 citation statements)

References 41 publications

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“…In this approach, the structural members are designed to have sufficient ductility to dissipate a large amount of energy through inelastic deformation and moment redistribution. With a more precise estimation of the flexural strength of RC members by further taking into account the strain gradient effect, it would allow engineers to predict more accurately the locations of plastic hinges and hence the deformability [39][40][41] of the members to cater for the calculated seismic demand [42][43][44].…”

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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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: Introductionmentioning

confidence: 99%

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

Ho¹,

Peng²

2011

Engineering Structures

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“…Although most empirical models did not account for the effects of concrete compressive strength f c on the plastic hinge length, some researchers still considered the plastic hinge length to be larger with higher f c . In this parametric study, f c is increased from 30 to 70 MPa.…”

Section: Parametric Studymentioning

confidence: 95%

“…The major factors affecting l sy of RECC beams are: (a) ECC compressive strength f c ; (b) ECC tensile properties; (c) rebar yielding strength f y ; (d) rebar hardening modulus E sh ; (e) tensile reinforcement ratio ρ s ; and (f) beam span z and beam effective depth d . Thus, by incorporating these factors, l sy for RECC beams could be expressed as

l_{sy} = ((), k_{1} {(f_{normalc} / f_{normaly})}^{α} {(E_{sh} / E_{normals})}^{β} {(1 / ρ_{normals})}^{γ} + k_{2}) d + k_{3} z,

where k 1 , k 2 , k 3 , α , β , and γ are real constants to be determined by regression analysis . The influences of ECC tensile response on l sy are ignored for the sake of simplicity.…”

Section: Proposed Empirical Model Of Plastic Hinge Length For Designmentioning

confidence: 99%

Development mechanism of plastic hinge in reinforced engineered cementitious composite beams under monotonic loading

Pan

et al. 2018

Structural Concrete

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Engineered cementitious composites (ECCs) are materials featuring strainhardening behavior with the formation of multiple cracks. When ECC is incorporated in structural applications such as beam, it is expected to significantly improve their mechanical performance. In this study, finite element analysis is performed to investigate the characteristics of the plastic hinge in reinforced ECC (RECC) beams. The plastic hinge lengths of RECC beams, involving rebar yielding zone, concrete crushing zone and curvature localization zone, are found to be much larger than those for reinforced concrete (RC) beams. Based on the above results, parametric studies on the plastic hinge lengths in RECC beams are conducted to study the influences of the tensile\compressive properties of ECC, yielding strength\hardening modulus\ultimate strain of tensile reinforcement, tensile\compressive reinforcement ratio and beam size. This theoretical study has shown that the existing empirical models for RC beams' plastic hinge length are not applicable to RECC beams which exhibit much longer plastic hinge length. A new empirical equation for predicting the plastic hinge lengths of RECC beams is thus proposed.

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“…Failure due to shear would be very brittle and should be avoided in design (Baczkowski and Kuang, 2008;Bukhari et al, 2010;Choi et al, 2010;Lu et al, 2009). A precise estimation of the beams' flexural strength would also allow engineers to predict the locations of plastic hinges (Bai and Au, 2008;Jaafar, 2008;Pam and Ho, 2009) and hence the deformability (Ho and Pam, 2010;Sebastian and Zhang, 2008;Wu et al, 2004) of members under extreme events. Engineers may then correctly design and detail the reinforcement within the plastic hinge region for the required ductility and rotation capacity (Spence, 2008;Zhou and Zheng, 2010).…”

Section: Introductionmentioning

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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Deformability evaluation of high-strength reinforced concrete columns

Cited by 21 publications

References 41 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

Development mechanism of plastic hinge in reinforced engineered cementitious composite beams under monotonic loading

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

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