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J G Teng - One of the best experts on this subject based on the ideXlab platform.
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finite element modeling of Intermediate Crack debonding in frp plated rc beams
Journal of Composites for Construction, 2011Co-Authors: Gm M Chen, J G Teng, J F ChenAbstract:Intermediate Crack-induced debonding (IC debonding) is a common failure mode of RC beams strengthened with externally bonded fiber-reinforced polymer (FRP) reinforcement. Although extensive research has been carried out on IC debonding, much work is still needed to develop a better understanding of the failure mode and a more reliable strength model. This paper presents an advanced finite-element (FE) model on the basis of the smeared-Crack approach for predicting IC debonding failure. Existing FE models of the same type are generally deficient in capturing localized Cracks (both their pattern and widths). This deficiency is overcome in the proposed FE model through the accurate modeling of interfaces between the concrete and both the internal steel and the external FRP reinforcements. The capability and accuracy of the proposed model are demonstrated through comparisons of its predictions with selected test results. The importance of accurate modeling of localized Cracking is also explained using numeric...
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Intermediate Crack debonding in frp strengthened rc beams fe analysis and strength model
Journal of Composites for Construction, 2007Co-Authors: J G Teng, Jianjing JiangAbstract:Reinforced concrete (RC) beams strengthened in flexure with a bonded fiber-reinforced polymer (FRP) plate may fail by Intermediate Crack (IC) debonding, in which debonding initiates at a critical section in the high moment region and propagates to a plate end. This paper first presents a finite-element (FE) model based on the smeared Crack approach for concrete for the numerical simulation of the IC debonding process. This finite-element model includes two novel features: (1) the interfacial behavior within the major flexural Crack zone is differentiated from that outside this zone and (2) the effect of local slip concentrations near a flexural Crack is captured using a dual local debonding criterion. The FE model is shown to be accurate through comparisons with the results of 42 beam tests. The paper also presents an accurate and simple strength model based on interfacial shear stress distributions from finite-element analyses. The new strength model is shown to be accurate through comparisons with the t...
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debonding failure along a softening frp to concrete interface between two adjacent Cracks in concrete members
Engineering Structures, 2007Co-Authors: J F Chen, H Yuan, J G TengAbstract:Abstract A concrete beam can be strengthened by bonding a fibre reinforced polymer (FRP) plate to the tension face, and a common failure mode for such beams involves the debonding of the FRP plate that initiates at a major flexural Crack, which is widely referred to as Intermediate Crack (IC) debonding. To understand IC and other debonding failures, the bond behaviour between FRP and concrete has been studied extensively using simple pull-off tests, in which a plate is bonded to a concrete prism and is subject to tension. However, the behaviour of the FRP-to-concrete interface in a beam can be significantly different from that captured in a pull-off test as, in a beam, whether debonding along the FRP-to-concrete interface occurs at a major flexural Crack or not depends on the conditions at this Crack as well as at the adjacent Crack on the path of the debonding propagation. This paper is therefore concerned with the debonding process of an FRP-to-concrete bonded joint where the FRP plate is subject to tension at both ends, which closely approximates the IC debonding process in a flexurally strengthened RC member. The same problem has been the topic of a previous study by the authors, where a bilinear local bond–slip model was employed for the FRP-to-concrete interface. However, that solution is rather complex and difficult to apply in practice. The aim of this study is to produce a simplified solution by employing the simple linearly softening local bond–slip law for the interface. Results from this simplified analytical solution are compared with those from the previous solution, showing little loss of accuracy in predicting the load–displacement response and the ultimate load. The most significant outcome of the new solution is a simple expression for the ultimate load of the bonded joint which offers the potential for direct practical application. While the emphasis of the paper is on FRP-to-concrete joints, the solution and methodology are applicable to similar joints between other materials such as FRP-to-steel or steel-to-concrete bonded joints.
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frp to concrete interfaces between two adjacent Cracks theoretical model for debonding failure
International Journal of Solids and Structures, 2006Co-Authors: J G Teng, H Yuan, J F ChenAbstract:Abstract External bonding of fibre reinforced polymer (FRP) composites has become a popular technique for strengthening concrete structures all over the world. The performance of the interface between FRP and concrete is one of the key factors affecting the behaviour of the strengthened structure. Existing laboratory research has shown that the majority of reinforced concrete (RC) beams strengthened with a bonded FRP soffit plate fail due to debonding of the plate from the concrete. Two types of debonding failures have been commonly observed: plate end debonding and Intermediate Crack induced debonding. In order to understand and develop methods to predict such debonding failures, the bond behaviour between concrete and FRP has been widely studied using simple shear tests on FRP plate/sheet-to-concrete bonded joints and a great deal of research is now available on the behaviour of these bonded joints. However, for Intermediate Crack induced debonding failures, the debonding behaviour can be significantly different from that observed in a simple shear test. Among other factors, the most significant difference may be that the FRP plate between two adjacent Cracks is subject to tension at both Cracks. This paper presents an analytical solution for the debonding process in an FRP-to-concrete bonded joint model where the FRP plate is subject to tension at both ends. A realistic bi-linear local bond-slip law is employed. Expressions for the interfacial shear stress distribution and the load–displacement response are derived for different loading stages. The debonding process is discussed in detail. Finally, results from the analytical solution are presented to illustrate how the bond length affects the behaviour of such bonded joints. While the emphasis of the paper is on FRP-to-concrete joints, the analytical solution is equally applicable to similar joints between thin plates of other materials (e.g. steel and aluminium) and concrete.
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Intermediate Crack induced debonding in rc beams and slabs
Construction and Building Materials, 2003Co-Authors: J G Teng, Scott T Smith, J Yao, J F ChenAbstract:Abstract A variety of debonding failure modes have been observed in tests on reinforced concrete (RC) beams strengthened by bonding fibre reinforced polymer (FRP) plates to their tension face. These can be broadly classified into two types: (a) those associated with high interfacial stresses near the ends of the bonded plate; and (b) those induced by a flexural or flexural-shear Crack away from the plate ends. The first type of failures has been extensively studied, leading to many strength models. By contrast, the second type of failures has received much less attention and no strength model appears to have been developed for it. This paper is, therefore, concerned with the second type of failures induced by a flexural or flexural-shear Crack, which is referred to as Intermediate Crack-induced debonding. The mechanism of this type of debonding failures is first examined briefly, highlighting the similarity between such debonding failures and those in simple shear tests of FRP-to-concrete bonded joints used for determining bond strengths. Based on this similarity, the recent Chen and Teng bond strength model is combined with a simple section analysis for predicting the strength of beams and slabs, which fail by Intermediate Crack-induced debonding. It is shown that through a simple modification of the Chen and Teng bond strength model, the proposed debonding strength model provides a good first approximation to the strengths of such beams. A design procedure for the flexural strengthening of beams incorporating the proposed debonding strength model is finally proposed.
J F Chen - One of the best experts on this subject based on the ideXlab platform.
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finite element modeling of Intermediate Crack debonding in frp plated rc beams
Journal of Composites for Construction, 2011Co-Authors: Gm M Chen, J G Teng, J F ChenAbstract:Intermediate Crack-induced debonding (IC debonding) is a common failure mode of RC beams strengthened with externally bonded fiber-reinforced polymer (FRP) reinforcement. Although extensive research has been carried out on IC debonding, much work is still needed to develop a better understanding of the failure mode and a more reliable strength model. This paper presents an advanced finite-element (FE) model on the basis of the smeared-Crack approach for predicting IC debonding failure. Existing FE models of the same type are generally deficient in capturing localized Cracks (both their pattern and widths). This deficiency is overcome in the proposed FE model through the accurate modeling of interfaces between the concrete and both the internal steel and the external FRP reinforcements. The capability and accuracy of the proposed model are demonstrated through comparisons of its predictions with selected test results. The importance of accurate modeling of localized Cracking is also explained using numeric...
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debonding failure along a softening frp to concrete interface between two adjacent Cracks in concrete members
Engineering Structures, 2007Co-Authors: J F Chen, H Yuan, J G TengAbstract:Abstract A concrete beam can be strengthened by bonding a fibre reinforced polymer (FRP) plate to the tension face, and a common failure mode for such beams involves the debonding of the FRP plate that initiates at a major flexural Crack, which is widely referred to as Intermediate Crack (IC) debonding. To understand IC and other debonding failures, the bond behaviour between FRP and concrete has been studied extensively using simple pull-off tests, in which a plate is bonded to a concrete prism and is subject to tension. However, the behaviour of the FRP-to-concrete interface in a beam can be significantly different from that captured in a pull-off test as, in a beam, whether debonding along the FRP-to-concrete interface occurs at a major flexural Crack or not depends on the conditions at this Crack as well as at the adjacent Crack on the path of the debonding propagation. This paper is therefore concerned with the debonding process of an FRP-to-concrete bonded joint where the FRP plate is subject to tension at both ends, which closely approximates the IC debonding process in a flexurally strengthened RC member. The same problem has been the topic of a previous study by the authors, where a bilinear local bond–slip model was employed for the FRP-to-concrete interface. However, that solution is rather complex and difficult to apply in practice. The aim of this study is to produce a simplified solution by employing the simple linearly softening local bond–slip law for the interface. Results from this simplified analytical solution are compared with those from the previous solution, showing little loss of accuracy in predicting the load–displacement response and the ultimate load. The most significant outcome of the new solution is a simple expression for the ultimate load of the bonded joint which offers the potential for direct practical application. While the emphasis of the paper is on FRP-to-concrete joints, the solution and methodology are applicable to similar joints between other materials such as FRP-to-steel or steel-to-concrete bonded joints.
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frp to concrete interfaces between two adjacent Cracks theoretical model for debonding failure
International Journal of Solids and Structures, 2006Co-Authors: J G Teng, H Yuan, J F ChenAbstract:Abstract External bonding of fibre reinforced polymer (FRP) composites has become a popular technique for strengthening concrete structures all over the world. The performance of the interface between FRP and concrete is one of the key factors affecting the behaviour of the strengthened structure. Existing laboratory research has shown that the majority of reinforced concrete (RC) beams strengthened with a bonded FRP soffit plate fail due to debonding of the plate from the concrete. Two types of debonding failures have been commonly observed: plate end debonding and Intermediate Crack induced debonding. In order to understand and develop methods to predict such debonding failures, the bond behaviour between concrete and FRP has been widely studied using simple shear tests on FRP plate/sheet-to-concrete bonded joints and a great deal of research is now available on the behaviour of these bonded joints. However, for Intermediate Crack induced debonding failures, the debonding behaviour can be significantly different from that observed in a simple shear test. Among other factors, the most significant difference may be that the FRP plate between two adjacent Cracks is subject to tension at both Cracks. This paper presents an analytical solution for the debonding process in an FRP-to-concrete bonded joint model where the FRP plate is subject to tension at both ends. A realistic bi-linear local bond-slip law is employed. Expressions for the interfacial shear stress distribution and the load–displacement response are derived for different loading stages. The debonding process is discussed in detail. Finally, results from the analytical solution are presented to illustrate how the bond length affects the behaviour of such bonded joints. While the emphasis of the paper is on FRP-to-concrete joints, the analytical solution is equally applicable to similar joints between thin plates of other materials (e.g. steel and aluminium) and concrete.
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Intermediate Crack induced debonding in rc beams and slabs
Construction and Building Materials, 2003Co-Authors: J G Teng, Scott T Smith, J Yao, J F ChenAbstract:Abstract A variety of debonding failure modes have been observed in tests on reinforced concrete (RC) beams strengthened by bonding fibre reinforced polymer (FRP) plates to their tension face. These can be broadly classified into two types: (a) those associated with high interfacial stresses near the ends of the bonded plate; and (b) those induced by a flexural or flexural-shear Crack away from the plate ends. The first type of failures has been extensively studied, leading to many strength models. By contrast, the second type of failures has received much less attention and no strength model appears to have been developed for it. This paper is, therefore, concerned with the second type of failures induced by a flexural or flexural-shear Crack, which is referred to as Intermediate Crack-induced debonding. The mechanism of this type of debonding failures is first examined briefly, highlighting the similarity between such debonding failures and those in simple shear tests of FRP-to-concrete bonded joints used for determining bond strengths. Based on this similarity, the recent Chen and Teng bond strength model is combined with a simple section analysis for predicting the strength of beams and slabs, which fail by Intermediate Crack-induced debonding. It is shown that through a simple modification of the Chen and Teng bond strength model, the proposed debonding strength model provides a good first approximation to the strengths of such beams. A design procedure for the flexural strengthening of beams incorporating the proposed debonding strength model is finally proposed.
Deric John Oehlers - One of the best experts on this subject based on the ideXlab platform.
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flexural strength and ductility of frp plated rc beams fundamental mechanics incorporating local and global ic debonding
Journal of Composites for Construction, 2016Co-Authors: Deric John Oehlers, P Visintin, Wade LucasAbstract:AbstractReinforced concrete (RC) beams and slabs are frequently strengthened or stiffened in flexure by adhesively bonding fiber-reinforced polymer (FRP) plates to their surfaces using a strain-based moment-curvature design technique. This design technique is generally based on the Intermediate Crack (IC) debonding strain of the FRP reinforcement, that is, on the start of IC debonding; from this analysis it is often deduced that FRP plating is ineffective at the ultimate limit state because FRP debonding occurs before yield of the steel reinforcement. In this paper, it is shown that the strain-based approach is generally a lower bound at the ultimate limit state. Instead, a displacement-based approach is described that shows that FRP plated beams can be designed to achieve a higher strength than that of the RC beam by itself no matter when IC debonding first occurs. The mechanics of the analysis approach developed here treat the FRP debonded plate as a FRP prestressing tendon with a force equal to the IC ...
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interfacial stress transfer of near surface mounted frp to concrete joints
Engineering Structures, 2008Co-Authors: M Mohamed S Ali, Deric John Oehlers, M C Griffith, R SeracinoAbstract:Adhesively bonding carbon FRP (CFRP) plates to the surfaces of reinforced concrete structures is now a well-established form of retrofitting with advanced design rules and mathematical models that quantify the debonding mechanisms. However, externally bonded plates tend to debond at low strains which limits the effectiveness of this retrofitting technique. Tests have shown that near surface-mounted CFRP plates, where the FRP plate is inserted and bonded to the grooves cut into the concrete cover, substantially increase the debonding strain which in turn leads to significant increases in material efficiency as well as flexural strength and ductility. In this paper, mathematical models and design equations are developed for predicting the Intermediate Crack debonding capacities of near surface-mounted plates and their accuracy is demonstrated by comparisons with test results.
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ic debonding of frp nsm and eb retrofitted concrete plate and cover interaction tests
Journal of Composites for Construction, 2008Co-Authors: Deric John Oehlers, R Seracino, Raizal Saifulnaz Muhammad RashidAbstract:The use of fiber-reinforced polymer (FRP) externally bonded (EB) plates is widely accepted as an efficient and unobtrusive retrofitting technique. FRP near-surface mounted plates are now also gradually gaining acceptance due to their substantial increase in debonding strains over EB plates. However tests have shown that the Intermediate Crack (IC) debonding resistances of FRP plates can be reduced by their interaction with adjacent parallel plates and with parallel free surfaces, that is the cover; this is often reflected in design rules where the IC debonding resistance of individual plates depends on the width of the plate as a proportion of the width of the concrete specimen and on the cover. In this paper, 22 new pull tests are reported that study the IC debonding interaction with adjacent plates and cover. The results are encouraging as they show that there is little reduction in the IC debonding resistance until the lateral cover or gap between plates is relatively small.
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Bond Strength of Near-Surface Mounted FRP Strip-to-Concrete Joints
Journal of Composites for Construction, 2007Co-Authors: Rudi Seracino, Nicola M. Jones, M.s. Mohamed Ali, Mark W. Page, Deric John OehlersAbstract:The retrofitting technique of near-surface mounting (NSM) fiber-reinforced polymer (FRP) bars/strips is receiving more attention recently due to a number of advantages over the externally bonded technique. However, there is insufficient data available in the existing literature to quantify the Intermediate Crack (IC) debonding mechanism of reinforced concrete members retrofitted with longitudinal NSM strips. As it is recognized that simple push — pull specimens simulate the IC debonding mechanism observed in retrofitted flexural members, this paper presents the results of a series of 36 push — pull tests using NSM strips to quantify the bond strength of such FRP-to-concrete joints. It is proposed that the confinement effect of the concrete surrounding the interface debonding Crack improves the shear stress transfer mechanism resulting in higher debonding plate strains compared with externally bonded plates. A nonlinear statistical analysis of the experimental data was undertaken to develop a model to predict the maximum axial plate force for IC debonding, taken at a critical bonded length of 200 mm.
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moment redistribution in adhesively plated rc beams and slabs
Advanced Polymer Composites for Structural Applications in Construction#R##N#Acic 2004, 2004Co-Authors: Deric John Oehlers, I. S. T. Liu, Rudi SeracinoAbstract:ABSTRACT It is common practice these days to retrofit RC beams and slabs by adhesive bonding FRP or steel plates to their surfaces. However, research has shown that these external plates can debond prematurely at relatively low strains, due to Intermediate Crack (IC) debonding, and in a brittle fashion. Because of these low IC debonding strains, it can be shown, through the standard use of neutral axis depth factors at ultimate, that the ability of the plated section to redistribute moment to other sections is severely limited and to such an extent that guidelines often preclude moment redistribution. This limitation may have little effect on plating RC bridges but it can, at least theoretically, severely limit the use of plating in buildings where ductility is a requirement. Tests on steel and FRP plated continuous beams have shown that moment redistribution can occur and a design procedure has been developed to determine the amount of moment redistribution for any type of plated section, such as tension face plates and side plates, and for any type of plate material, such as steel or FRP. In this paper, an analysis approach to quantify the amount of moment redistribution is described. A parametric study is then used to illustrate how the plate material and geometric properties affect moment redistribution; in particular, the study looks at the effect of using carbon FRP plates and glass FRP plates, as well as steel plates that have been designed to either debond prior to yielding or yield prior to IC debonding. In summary, the paper will show that plated sections can redistribute moment and, hence, the present restriction can be removed which should extend the use of retrofitting by plating. Furthermore, the moment redistribution analysis procedure allows the engineer the freedom to choose the properties of the plate to design for moment redistribution.
Sofiane Amziane - One of the best experts on this subject based on the ideXlab platform.
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general cohesive zone model for prediction of interfacial stresses induced by Intermediate flexural Crack of frp plated rc beams
Engineering Structures, 2016Co-Authors: M L Bennegadi, K Hadjazi, Z Sereir, Sofiane Amziane, El B MahiAbstract:Abstract In this paper, a general model is developed to predict the distribution of interfacial shear and normal stresses induced by Intermediate flexural Crack of FRP-plated reinforced concrete beam. For that, a new theoretical model based on the bi-linear cohesive zone model for Intermediate Crack-induced debonding is established, with the unique feature of unifying debonding initiation and growth. The stress deformation relationship is generally referred to as bond-slip law since the deformation of the interface is mainly the relative displacement (slip) between the FRP plate and the reinforced concrete beam (RC beam). Adherent shear deformations have been included by assuming a parabolic shear stress through the thickness of the adherents, verifying the cubic variation of the longitudinal displacement function, whereas all existing solutions neglect this effect. To obtain interfacial normal stress, the adhesive layer is assumed in linearly elastic stage in normal direction. This assumption is adopted in this study, because the FRP plate and RC beam are in contact during the whole debonding process. A complementary experimental study is made in order to show the debonding process according to mechanical and geometrical characteristics of adhesive and FRP plate. Analytical results obtained through the closed-form of interface stresses are in good agreement with those given by numerical and experimental models. Finally, parametric studies are carried out to demonstrate the effect of the mechanical properties and thickness variations of FRP, concrete and adhesive on interface debonding.
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creep response of Intermediate flexural Cracking behavior of reinforced concrete beam strengthened with an externally bonded frp plate
International Journal of Solids and Structures, 2016Co-Authors: K Hadjazi, Z Sereir, Sofiane AmzianeAbstract:Abstract In this study, a creep response model for the long-term behavior of interfacial shear stresses induced by Intermediate flexural Crack of FRP-plated RC beams is developed. A theoretical model based on the bi-linear cohesive zone model for Intermediate Crack-induced debonding is established, with the unique feature of unifying debonding initiation and growth with time increments. The creep behavior of the RC beam, adhesive layer and FRP plate have been included by considering the time-dependent mechanical properties. The time-dependent stress-deformation relationship caused by creep is referred to as bond-slip law. Consequently, a new interfacial law which combines time-dependent mechanical properties of all retrofitted beam constituents is proposed by considering constant the total energy during the creep response with Intermediate Crack. Obtained results are in good agreement with those given in literature. A parametric study is carried out to demonstrate the effect of the mechanical properties and thickness variations of FRP, concrete and adhesive on interface debonding. Indeed, the creep behavior, activates the debonding process in long term. Size of the softening zone is reached quickly and the bearing capacity of the retrofitted beam will be relatively affected by the time increase.
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cohesive zone model for the prediction of interfacial shear stresses in a composite plate rc beam with an Intermediate flexural Crack
Composite Structures, 2012Co-Authors: K Hadjazi, Z Sereir, Sofiane AmzianeAbstract:Abstract In this paper, an analytical method is developed to predict the distribution of interfacial shear stresses in concrete beams strengthened by composite plates. Accurate predictions of such stresses are necessary when designing to prevent debonding induced by a central flexural Crack in a FRP-plated reinforced concrete (RC) beam. In the present analysis, a new theoretical model based on the bi-linear cohesive zone model for Intermediate Crack-induced debonding is established, with the unique feature of unifying debonding initiation and growth. Adherent shear deformations have been included in the present theoretical analyses by assuming a parabolic shear stress through the thickness of the adherents, verifying the cubic variation of the longitudinal displacement function, whereas all existing solutions neglect this effect. The results obtained for interfacial shear stress distribution near the Crack are compared to the Jialai Wang analytical model and the numerical solutions are based on finite element analysis. Parametric studies are carried out to demonstrate the effect of the mechanical properties and thickness variations of FRP, concrete and adhesive on interface debonding. Indeed, the softening zone size is considerably larger than that obtained by other models which neglect adherent shear deformations. However, loads at the limit of the softening and debonding stages are larger than those calculated without the thickness effect. Consequently, debonding at the interface becomes less apparent and the lifespan of our structure is greater.
R Seracino - One of the best experts on this subject based on the ideXlab platform.
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bond behaviour of frp to clay brick masonry joints
Engineering Structures, 2009Co-Authors: C Willis, Q Yang, R Seracino, M C GriffithAbstract:Abstract The out-of-plane bending and in-plane shear response of unreinforced modern clay brick masonry walls retrofitted with fibre-reinforced polymer (FRP) strips is often governed by debonding failure mechanisms. Hence, it is necessary to quantify the fundamental interface bond–slip model, which describes the debonding behaviour of the FRP-to-masonry interface. This paper presents the results of a series of 29 pull tests investigating the use of externally bonded (EB) and near surface mounted (NSM) retrofitting techniques. Test variables included: surface preparation; geometric properties; location of FRP (relative to perpend joints and cores); bonding agent of bed joints (mortar and quick drying paste); bonding method for glass fibre sheets (plate bonding and dry lay-up); and FRP material. A discussion of the test results and preliminary practical recommendations are also provided. A model used to predict the Intermediate Crack debonding resistance was verified against the test data. The model is generic in that it is applicable to both the EB and NSM retrofitting techniques. This generic model was shown to give very good ultimate strength predictions for the series of 29 pull tests conducted as part of this research.
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interfacial stress transfer of near surface mounted frp to concrete joints
Engineering Structures, 2008Co-Authors: M Mohamed S Ali, Deric John Oehlers, M C Griffith, R SeracinoAbstract:Adhesively bonding carbon FRP (CFRP) plates to the surfaces of reinforced concrete structures is now a well-established form of retrofitting with advanced design rules and mathematical models that quantify the debonding mechanisms. However, externally bonded plates tend to debond at low strains which limits the effectiveness of this retrofitting technique. Tests have shown that near surface-mounted CFRP plates, where the FRP plate is inserted and bonded to the grooves cut into the concrete cover, substantially increase the debonding strain which in turn leads to significant increases in material efficiency as well as flexural strength and ductility. In this paper, mathematical models and design equations are developed for predicting the Intermediate Crack debonding capacities of near surface-mounted plates and their accuracy is demonstrated by comparisons with test results.
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ic debonding of frp nsm and eb retrofitted concrete plate and cover interaction tests
Journal of Composites for Construction, 2008Co-Authors: Deric John Oehlers, R Seracino, Raizal Saifulnaz Muhammad RashidAbstract:The use of fiber-reinforced polymer (FRP) externally bonded (EB) plates is widely accepted as an efficient and unobtrusive retrofitting technique. FRP near-surface mounted plates are now also gradually gaining acceptance due to their substantial increase in debonding strains over EB plates. However tests have shown that the Intermediate Crack (IC) debonding resistances of FRP plates can be reduced by their interaction with adjacent parallel plates and with parallel free surfaces, that is the cover; this is often reflected in design rules where the IC debonding resistance of individual plates depends on the width of the plate as a proportion of the width of the concrete specimen and on the cover. In this paper, 22 new pull tests are reported that study the IC debonding interaction with adjacent plates and cover. The results are encouraging as they show that there is little reduction in the IC debonding resistance until the lateral cover or gap between plates is relatively small.