Damage of bond in reinforced concrete: A detailed finite element analysis

Abstract

Numerical simulation of the bond is a powerful and versatile tool to analyze different aspects of reinforcement and concrete interaction, such as the formation of internal cracks, damage of concrete around the bar or bond degradation near the cracks. In the present study, a three‐dimensional rib‐scale finite element modeling technique was employed to study the latter phenomena. Numerical models were calibrated using the experimentally measured reinforcement strain profiles in the short tensile reinforced concrete elements reported herein and elsewhere. The selected experimental programs cover a wide range of bar diameters (10–29 mm) that are commonly used in the engineering practice. A parametric analysis was performed to identify the key parameters affecting the bond stress distribution in the vicinity of cracks. Based on the results of the parametric analysis, a simple bond damage model was proposed. Unlike the existing models, which take into account a single parameter, namely, bar diameter, the proposed bond damage model also considers the effect of concrete grade and reinforcement strain in the cracked section.

Experimental and Numerical Investigation of Bond-Slip Behavior of High-Strength Reinforced Concrete at Service Load

“…Indeed, it is an intermediate study that in the future may be used for developing a constitutive law of bond-slip, similar to the ones proposed by Desir et al [ 31 ] or Kanakubo et al [ 37 ]. Similar to the latter research’s findings, earlier findings [ 8 ] by the authors explicated the assessment of bond stress reduction at the close proximity of cracks (end of the element) from the descending branch of a bond-slip law.…”

“…In the present study, the normal and shear stiffness of 2 × 10 8 MN/m 3 were assumed. It was earlier shown by the authors that, for adequate bond analysis, the interface failure must occur so as to allow the slip between the reinforcement and concrete elements [ 8 ]. Consequently, the interface strength, rather than stiffness, becomes the governing parameter controlling the numerical outputs.…”

“…Consequently, the interface strength, rather than stiffness, becomes the governing parameter controlling the numerical outputs. After the interface failure, the load from reinforcement to concrete is mostly transferred by the direct bearing of the ribs to concrete [ 8 ]. Thus, rib height is the second critical parameter for the force transfer from the reinforcement to the surrounded concrete [ 17 ].…”

“…Nevertheless, non-uniform bond stress distribution, compressive stress fields, structural deformation of the specimen, and a different slip at the loaded and free ends may misrepresent the “local” bond-slip phenomenon [ 7 ]. Moreover, the force-displacement experimental set up represents the average bond stress within the anchorage length and bond deterioration effect at the loaded end of reinforcement cannot be directly evaluated [ 8 ]. As the anchorage length in the pull-out test set ups is kept at the minimum [ 2 ] (generally less that 5D, where D is the bar diameter), the bond deterioration may significantly distort the “local“ bond-slip relationships.…”

“…Recently, it was shown that a refined rib-scale FE model can also be employed to study the reinforcement strain profile as well as the internal cracking of concrete in the tensile RC prisms; these may be accurately represented using a refined rib-scale FE models [ 17 ]. Such models allow an in-depth analysis of not only the distribution of bond stresses and slip, but also the deterioration of concrete at the loaded end of reinforcement [ 8 ].…”