Intermediate Crack Debonding of Polymer Cement Mortar Overlay-Strengthened RC Beam

Zhang, Dawei; Ueda, Tamon; Furuuchi, Hitoshi

doi:10.1061/(asce)mt.1943-5533.0000240

Cited by 30 publications

(17 citation statements)

References 16 publications

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“…Cracking in overlay-strengthened RC structures has a major influence on structural performance, including tensile, bending and shear stiffness, energy absorption capacity, ductility and corrosion resistance of reinforcement. Moreover, the average crack spacing of overlaystrengthened beams plays an important role in transferred shear stress along overlay-substrate interface and normal stress generated in the substrate concrete in case when the premature debonding failure is investigated (Zhang et al 2010;Wang and Ling 1998;Raoof and Hassanen 2000). It is, therefore, necessary to predict the cracking behavior of overlay-strengthened RC beam.…”

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confidence: 99%

Average Crack Spacing of Overlay-Strengthened RC Beams

Zhang

Ueda

Furuuchi

2011

J. Mater. Civ. Eng.

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Abstract:The research is focused on evaluating the average crack spacing of overlay-strengthened reinforced concrete (RC) beams. The current equations in different structural codes for predicting the average crack spacing of RC beam with multilayered-reinforcing bars is proved to be inapplicable for overlay-strengthened RC beam, although these two kinds of beams are both with reinforcement in multi-layers. Therefore, a simple, practical and new analytical model that is capable of predicting the average crack spacing of overlay-strengthened beams is developed. An overlay-strengthened beam element is analyzed based on equilibrium and compatibility equations to formulate the average stresses of concrete, overlay and tension reinforcement. A series of verification comparisons with the experimental investigations, which involved various types of beam elements, are performed to verify the validity and reliability of the model. The proposed model performs satisfactorily with respect to measured response from the experimental database.Keyword: crack spacing; overlay; strengthening; interface; bond; multilayered-reinforcement BackgroundOverlaying is considered as a major retrofitting method for flexural and fatigue strengthening or retrofitting of concrete flexural members. As illustrated in Fig Cracks in overlay-strengthened RC structures may be expected because of the relatively low tensile strength of concrete and overlay materials and the use of high strength reinforcement in substrate and overlay. Cracking in overlay-strengthened RC structures has a major influence on structural performance, including tensile, bending and shear stiffness, energy absorption capacity, ductility and corrosion resistance of reinforcement. Moreover, the average crack spacing of overlaystrengthened beams plays an important role in transferred shear stress along overlay-substrate interface and normal stress generated in the substrate concrete in case when the premature debonding failure is investigated (Zhang et al. 2010;Wang and Ling 1998;Raoof and Hassanen 2000). It is, therefore, necessary to predict the cracking behavior of overlay-strengthened RC beam.Despite the fact that many design models have been provided by different structural codes or individual researchers with respect to average crack spacing of RC members with single or multilayered-reinforcement (JSCE 2007; EC2 2004; CSA 2004; NS 1992; CEB-FIP 1990;Broms 1965;Albandar and Mills 1974;Bặzant and Oh 1983;Rizk and Marzouk 2010;Dawood and Marzouk 2010;Marzouk et al. 2010;Rizkalla et al. 1983;Rizkalla and Hwang 1984), which are similar to overlay-strengthened RC member with reinforcement layers in the substrate and overlay, their applicability for overlay-strengthened beams has not yet been investigated.The main objective of this study is to develop a rational methodology for predicting the average crack spacing of overlay-strengthened RC beam. Firstly, the predicted average crack spacing based on existing models from several design specifications is compared with that from expe...

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confidence: 99%

Average Crack Spacing of Overlay-Strengthened RC Beams

Zhang

Ueda

Furuuchi

2011

J. Mater. Civ. Eng.

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“…According to different load-deflection behaviors, it can be further subdivided into interface debonding before and after the yielding of reinforcement. The former is due mainly to an increasing interface bonding requirement with the applied load beyond the interface bonding strength between UHTCC and concrete, whereas the latter may arise from the decreasing bonding strength when the elastic modulus of reinforcement reduced after yielding, as indicated by Zhang et al (2011). Figure 7 shows the crack pattern at ultimate failure for beams presenting interface debonding.…”

Section: Interface Debonding Behaviormentioning

confidence: 99%

“…The study by Zhang et al (2011) indicated that the PCM (polymer cement mortar) overlay-strengthening beams showed end debonding and intermediate crack debonding. End debonding was avoided as a result of the confinement of the support reaction force applied on the bottom of RC/UHTCC beams.…”

Section: Interface Debonding Behaviormentioning

confidence: 99%

Flexural and Interface Behaviors of Reinforced Concrete/Ultra-high Toughness Cementitious Composite (RC/UHTCC) Beams

Hou

Hong

et al. 2015

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This paper presents an experimental investigation on the response of reinforced concrete (RC) beams with the use of ultra-high toughness cementitious composite (UHTCC) in the tension zone. Two parameters, the longitudinal reinforcement ratio and the depth of UHTCC layer, were varied. The failure mechanism, flexural behavior, interface performance, and cracking pattern were compared between RC and RC/UHTCC beams as well as between RC/UHTCC beams with different depths of the UHTCC layer. The experimental results revealed that the yielding load was improved apparently for beams with a reinforcement ratio of 0.67%, and the macro wide cracks in concrete turned into multiple tight cracks in the UHTCC layer depending on the prominent crack dispersion capacity of the UHTCC. However, RC/UHTCC beams with 1.0% and 1.73% reinforcement ratios showed shear-interface debonding failure prior to the yielding of reinforcement, and the failure resulted from the accumulated interface crack extension up to the support and the crush of concrete. Moreover, the theoretical analysis indicates that the interface cracking strength and ultimate interface bonding strength are related with the reinforcement ratio and UHTCC depth. The tensile stress difference of reinforcement in the UHTCC layer plays a controlling role in the interface debonding between concrete and UHTCC. The present study provides significant insights for the engineering application of hot-casting RC/UHTCC composite beam.

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“…Subsequently, research on the use of Fiber-Reinforced Plastic (FRP) laminates became more prevalent (Gao et al 2004a,b;Maalejand and Bian 2001;Rahimi and Hutchinson 2001;Fanning and Kelly 2001;Quantrill et al 1996;Garden and Hollaway 1998;garden et al 1997;Arduini et al 1997;Nguyen et al 2001;Ahmed andVan Gemert 1999a,b;Beber et al 1999;Smith and Teng 2002;Oller 2009;Wu et al 2005). Most recently, the literature has focused on the use of overlays (Zhang et al 2009(Zhang et al , 2011a(Zhang et al ,b, 2012Satoh and Kodama 2005). The overlay method consists of arranging tension reinforcements (such as steel bars or FRP grids) under the lower surface of concrete members.…”

Section: Introductionmentioning

confidence: 99%

A Design Proposal for Concrete Cover Separation in Beams Strengthened by Various Externally Bonded Tension Reinforcements

Zhang

Ueda

Furuuchi

2012

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Abstract:Previous research has shown that the application of externally bonded reinforcements (steel plates, fiber-reinforced polymer (FRP) laminates, overlays, etc.) to strengthen reinforced concrete (RC) beams can lead to brittle debonding failures before the ultimate load is reached. The aim of this study is to develop an analytical approach for the flexural strengthening of existing structures using various types of external reinforcements and predicting the debonding failure. In this study, an analytical model is developed to predict concrete cover separation failure in beams with overlay strengthening that is also applicable to strengthening using other reinforcements, such as steel plates and FRP laminates. An experimental database with various types of beam specimens is used to verify the model's validity and reliability. A concept for determining the effective strengthening capacity in a strengthening design is presented and the main parameters affecting the strengthening capacity are investigated. Finally, a design proposal is presented for the flexural strengthening of RC beams with respect to concrete cover separation failure. This proposal contributes to the application of external flexural strengthening in practical design.

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Intermediate Crack Debonding of Polymer Cement Mortar Overlay-Strengthened RC Beam

Cited by 30 publications

References 16 publications

Average Crack Spacing of Overlay-Strengthened RC Beams

Average Crack Spacing of Overlay-Strengthened RC Beams

Flexural and Interface Behaviors of Reinforced Concrete/Ultra-high Toughness Cementitious Composite (RC/UHTCC) Beams

A Design Proposal for Concrete Cover Separation in Beams Strengthened by Various Externally Bonded Tension Reinforcements

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