Compression Field Analysis of Fiber-Reinforced Concrete Based on Cracked Membrane Model

Kaufmann, Walter; Mata‐Falcón, Jaime; Amin, Ali

doi:10.14359/51716763

Cited by 18 publications

(12 citation statements)

References 31 publications

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“…In fact, despite this crude simplification, the TCM reveals excellent agreement with experimental data 26,29 . Because of its good correlation with experimental data and its simplicity, the TCM is widely applicable and builds part of many complex models such as the Cracked Membrane Model 30–32 or models investigating the serviceability limit states of structural concrete 33 . It was further enhanced for very small strains, 34 bending elements, 22,23 and reversed loading 29 …”

Section: Tcm and Ctcm Model Descriptionmentioning

confidence: 94%

Corroded Tension Chord Model: Load‐deformation behavior of structures with locally corroded reinforcement

Haefliger

Kaufmann

2021

Structural Concrete

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Localised corrosion may considerably impair the load‐bearing and deformation capacity of reinforced concrete structures. The Corroded Tension Chord Model allows investigating the related effects. The model combines the effects of tension stiffening and strain localisation due to a local cross‐section loss to calculate the load‐deformation behaviour of tension members and entire structural elements containing locally corroded reinforcing bars on a sound mechanical basis. Based on simple equilibrium considerations, the critical loss of cross‐sectional area is introduced, beyond which most of a reinforcing bar's ductility or a structure's deformation capacity, respectively, is lost. For conventional European reinforcing steel, even small cross‐section losses may be sufficient to impair ductility drastically. Illustrative calculations on structural elements with various spatial corrosion distributions but identical mean cross‐section loss reveal that the load‐deformation behaviour strongly depends on the specific corrosion parameters: Structures with few heavily corroded reinforcing bars seem to be less critical regarding strength and deformation capacity than structures with many slightly corroded reinforcing bars.

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Section: Tcm and Ctcm Model Descriptionmentioning

confidence: 94%

Corroded Tension Chord Model: Load‐deformation behavior of structures with locally corroded reinforcement

Haefliger

Kaufmann

2021

Structural Concrete

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“…due to the discontinuous nature of the reinforcement. While such variations could theoretically be accounted for [1], mechanical models commonly neglect throughthickness variations [2][3][4][5][6][7]. Accordingly, direct experimental validation of crack phenomena in these models can be carried out based on crack kinematic measurements on the surface.…”

Section: Introductionmentioning

confidence: 99%

Refined extraction of crack characteristics in large-scale concrete experiments based on digital image correlation

Gehri

Mata‐Falcón

Kaufmann

2022

Engineering Structures

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The accurate extraction of the crack patterns and measurements of crack kinematics are essential for understanding the mechanical behaviour in experiments on structural concrete as well as in the validation and further development of sound mechanical models. This paper presents important refinements of the authors' recently published automatic crack detection and measurement procedure (ACDM) based on surface displacement measurements obtained with digital image correlation (DIC). The proposed refinements are crucial for reliably assessing the crack behaviour in large-scale experiments with complex crack patterns, since the original methods of ACDM may fail or result in biased measurements at locations with closely spaced cracks, crack intersections or cracks with high morphological curvature. The main refinements are (i) a Canny edge-based crack detector, which is applied on the DIC major principal strain field and (ii) enhancements in the crack kinematic measurement to assess the reliability of the results. The latter includes the automatic selection of optimum reference points used in the crack kinematic measurement to increase its reliability and remove uncertain results. The refined ACDM procedure is validated using several large-scale 2.0 × 2.0 m shear panel experiments with highly complex crack patterns. Compared to the original ACDM, significantly thinner cracks can be detected with a much higher reliability of crack locations and crack kinematic measurements, particularly close to crack intersections and at closely spaced cracks. Additionally, two approaches for the statistical consolidation of the large amount of gathered data into characteristic crack properties in large-scale homogeneous concrete element experiments are proposed and compared. The results show that the statistical consolidation of the ACDM data using a 95%-quantile match well with the direct extraction of the best-fit homogeneous crack properties from the fullfield DIC displacements. The consolidated data provides highly valuable insight into the mechanical behaviour, especially regarding crack phenomena.

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“…The stress in the conventional reinforcement at any point between the primary crack and the location between two primary cracks may also be determined as:

σ_{s} ((), x) = T_{s} / A_{st} - 4 τ_{b} x / d_{b} \dots 0 \leq x \leq s_{normalr, \max} / 2

where T s is the force in the reinforcing bar at a primary crack, which may be calculated from a sectional analysis. Setting Equation () to f ct at x = s r,max /2 yields an expression for s r,max :

s_{normalr, \max} = \frac{d_{b} ((), f_{ct} - f_{w})}{2 τ_{b} ρ_{tc}} \geq l_{f}

The limiting term in Equation (), l f , is the fiber length and was introduced by Kaufmann et al 12 For large fiber dosages (i.e., for f w ~ f ct ), Equation () may yield very small crack spacings. This is, however, physically impossible, as for small crack openings, the embedment length of the fibers would be too short to develop enough tension to warrant such stresses 12 .…”

Section: Instantaneous Behavior and Crack Spacing In Frc Flexural Membersmentioning

confidence: 99%

“…Setting Equation () to f ct at x = s r,max /2 yields an expression for s r,max :

s_{normalr, \max} = \frac{d_{b} ((), f_{ct} - f_{w})}{2 τ_{b} ρ_{tc}} \geq l_{f}

Section: Instantaneous Behavior and Crack Spacing In Frc Flexural Membersmentioning

confidence: 99%

Simplified time‐dependent crack width prediction for fiber reinforced concrete flexural members

Watts

Amin

Gilbert

et al. 2021

Structural Concrete

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One of the main areas where it is generally accepted that fibers play a significant contribution in construction practice is in the control of cracking. The primary objective of the fibers is to traverse cracks after they nucleate. The fibers provide some post‐cracking resistance to the otherwise brittle concrete. Much of the research contained in the literature on the cracking behavior of fiber reinforced concrete (FRC) members has focused on instantaneous load scenarios, without much consideration for the long‐term behavior (i.e., for members which are subjected to a sustained service moment). This is mirrored in design standards where limited guidance is provided to engineers to predict and assess the long‐term serviceability performance of FRC members. This paper presents a simplified model, which may be suitable for design, that can reliably predict the cracking behavior, over time, of FRC members subjected to a sustained in‐service flexural load. Predictions of the proposed model are compared to both instantaneous and long‐term data available in the literature. Satisfactory correlation is observed.

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Compression Field Analysis of Fiber-Reinforced Concrete Based on Cracked Membrane Model

Abstract: His research interests include the design and analysis of conventionally and digitally fabricated concrete structures.

Cited by 18 publications

References 31 publications

Corroded Tension Chord Model: Load‐deformation behavior of structures with locally corroded reinforcement

Corroded Tension Chord Model: Load‐deformation behavior of structures with locally corroded reinforcement

Refined extraction of crack characteristics in large-scale concrete experiments based on digital image correlation

Simplified time‐dependent crack width prediction for fiber reinforced concrete flexural members

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