Nonlinear Analysis of Shear-Critical Reinforced Concrete Beams Using Fixed Angle Theory

Lee, Jung-Yoon; Kim, Sang-Woo; Mansour, Mohamad

doi:10.1061/(asce)st.1943-541x.0000345

Cited by 20 publications

(27 citation statements)

References 22 publications

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“…The design approach as specified in various Codes [1,2] suggests that the RC beam should be designed to fail in a ductile manner. Since the rupture of RC beam due to shear stress is a brittle one [3], consequently the shear capacity of the beam must be intended to be more conservative than the corresponding flexural strength. It means any excessive loads beyond the design load should lead to flexural type of failure.…”

Section: Introductionmentioning

confidence: 99%

Cracking behaviour and its effect on the deflection of patched-reinforced concrete beam under flexural loading

et al. 2017

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Abstract. Under the influence of aggressive environment, structural concrete could exhibit degradation in various forms. One of the symptoms of the degradation could be shown in the form of local delamination of concrete cover. Patching method could be a preference choice to repair this type of degradation to regain its structural performance and durability. This paper presents the structural behaviour of patched-reinforced concrete beam under flexural loading with particular interest on the use of unsaturated polyester resin (UPR) mortar as patch repair material. The repair area is replicated in the tensile zone of the beam. The behaviour investigated in this study is the cracking evolution of the patchedreinforced concrete beam and its effect on the deflection. It is shown that the higher strength of the UPR-mortar leads to a reduction in the intensity of cracks compared to that of un-repaired (normal) reinforced concrete beam. The lesser cracks intensity is beneficial to restore the flexural stiffness of the beam.

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Section: Introductionmentioning

confidence: 99%

Cracking behaviour and its effect on the deflection of patched-reinforced concrete beam under flexural loading

et al. 2017

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“…Fig. 5 compares the observed shear stress-shear strain behaviour of six beam specimens in series S1 and S2 of Lee et al [18] with the behaviour predicted by the SMM and RA-STM. The figure suggests that the proposed analysis method can trace the non-linear behaviour of sheardominated RC beams up to the point of failure more accurately than the RA-STM.…”

Section: Verification Of Proposed Analysis Methodsmentioning

confidence: 73%

“…Section C-C is placed at a distance equal to the effective shear depth d ef of the beam from the maximum moment section. The effective shear depth d ef is taken as 0.9d [17,18], where d is the effective depth of the beam measured from the extreme compression fibre to the centroid of the outermost layer of tensile steel, see Fig. 1.…”

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confidence: 99%

Non‐linear analysis of shear‐critical reinforced concrete beams using the softened membrane model

Kassem

2015

Structural Concrete

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IntroductionWhereas the flexural behaviour of reinforced concrete (RC) beams is now well understood, accurate prediction of shear behaviour remains a challenge due to the complexity associated with the shear transfer mechanism [1]. Shear failure is rather brittle and sudden, and usually occurs with no advance warning of distress. It is thus highly undesirable and should be avoided if a ductile behaviour is achievable.Over the past three decades, significant attention has been devoted to developing mathematical models for predicting the behaviour and ultimate shear capacity of sheardominated RC beams. The models included those based on compression field theory (CFT), the rotating angle softened truss model (RA-STM), the fixed angle softened truss model (FA-STM), the softened membrane model (SMM) and the strut-and-tie model (STM). Moreover, experimentally validated non-linear finite element-based models [2][3][4] can further help in the accurate application of the design and analysis models available.The strut-and-tie model is reported to provide reasonable predictions of the shear strength, shear transmission mechanism and shear failure behaviour of shear-critical beams and deep beams, but the method cannot be used to predict beam deformations [5]. Although CFT has been used to predict the non-linear behaviour of cracked reinforced concrete membrane elements, the theory ignores the effect of concrete tension stiffening [6]. Later, the effect of concrete tension stiffening was introduced in modified compression field theory by imposing a concrete tensile stress across the shear crack, and as a result the accuracy significantly improved [7]. The effect of concrete tension stiffening was also included in the RA-STM by assuming a shear stress in the crack direction [1,8,9]. However, the RA-STM suffered a number of drawbacks, including the inaccurate prediction of the shear stress-shear strain behaviour of RC elements tested under pure shear and combined shear and flexure, and the inability to predict shear ductility [10]. Further, the RA-STM pays no attention to either the shear resistance of concrete struts or the Poisson's effect. On the other hand, the FA-STM can predict the 'contribution of concrete' V c , but the model implements a complicated empirical constitutive relationship of cracked concrete in shear and still ignores the Poisson's effect [10][11][12].The main difference between the latter two models is that the RA-STM is based on the assumption that the direction of cracks is perpendicular to the principal tensile stress in the concrete element. In contrast, the FA-STM is based on the assumption that the direction of subsequent cracks is perpendicular to the applied principal tensile stress. Further, the softened membrane model takes account of the stresses and strains in a biaxial condition due to the Poisson's effect and could be used to provide accurate predictions of both the pre-and post-peak behaviour of concrete elements tested under pure shear [13][14][15]. Both the RA-STM and the FA-STM were used...

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“…It is worth noting that the existing fixed-angle theories (Pang and Hsu 1996;Hsu and Zhang 1997) applied the compressive stress-strain relationships of concrete determined in the principal stress direction to that in the initial fixed-crack direction. Therefore, the stresses and strains calculated by these relationships gradually differ from the actual stresses and strains in the initial fixed-crack direction because the deviation angle ( β ) between the crack angle ( 2 α ) and the principal stress angle ( α ) increases as externally applied load inceases (Lee and Mansur 2006;Lee et al 2011). To take such a deviation angle into account in this study, the stresses and strains in the crack direction (direction 2-1) were calculated by transforming the stresses and strains in the principal direction (direction d-r) by the angle of β (refer to Figs.…”

Section: Tortional Behavior Model For Sfrc Membersmentioning

confidence: 99%

“…7. The initial value of β is taken as zero for calculations because the initial crack angle ( 2 α ) coincides with the principal stress angle ( α ) (Lee and Mansur 2006;Lee et al 2011). The stresses of concrete, steel bars, and steel fibers can be determined by selecting the average principal compressive strain ( d ε ) with assumed values of the average shear strain ( 12 γ ) and the average princi- …”

Section: Solution Algorithmmentioning

confidence: 99%

Fixed-Angle Smeared-Truss Approach with Direct Tension Force Transfer Model for Torsional Behavior of Steel Fiber-Reinforced Concrete Members

Lee

Hwang

et al. 2013

ACT

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The existing analysis models for torsional strength or torsional behavior of steel fiber reinforced concrete (SFRC) members typically adopted a simple approach, in which the tensile constitutive model of conventional concrete was modified appropriately for the SFRC considering that the steel fibers and concrete matrix behave in a fully composite manner. In such approaches, however, the pull-out behavior of the steel fibers at crack interfaces caused by the progressive loss of bond stress developed between the fiber and surrounding concrete is hard to be described in detail, and they also requires much experimental effort and cost to derive the constitutive models of SFRCs in tension for various types of SFRCs. In this study, steel fibers are modeled as separate direct tension force transfer elements and applied to a modified fixed-angle smeared-crack truss model for torsion so that the bond mechanism between the steel fibers and concrete matrix can be reflected in the tensile behavior of SFRC further in detail. The proposed fixed-angle model approach for torsional behavior of SFRC members take into account the difference between principal stress and cracking angle, and well reflects the unique characteristics of SFRC, such as fiber directionality and bond mechanism. The proposed approach provided a good agreement with the torsional behavior of 48 specimens obtained from previous studies.

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Nonlinear Analysis of Shear-Critical Reinforced Concrete Beams Using Fixed Angle Theory

Cited by 20 publications

References 22 publications

Cracking behaviour and its effect on the deflection of patched-reinforced concrete beam under flexural loading

Cracking behaviour and its effect on the deflection of patched-reinforced concrete beam under flexural loading

Non‐linear analysis of shear‐critical reinforced concrete beams using the softened membrane model

Fixed-Angle Smeared-Truss Approach with Direct Tension Force Transfer Model for Torsional Behavior of Steel Fiber-Reinforced Concrete Members

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