Local bond stress-slip model for reinforced concrete joints and anchorages with moderate confinement

Abstract

This paper presents a summary of an experimental investigation and the derivation of a bond-slip model for reinforcing steel embedded in moderately confined concrete under monotonic and cyclic loadings. Moderately confined concrete encompasses the domain between unconfined and well-confined concrete, the limits of which are defined in the paper. The proposed constitutive law adapts and extends the well-known Eligehausen-Filippou law for wellconfined concrete to moderately confined concrete. It is described by an envelope curve and degradation rules. The former is obtained through a confinement index, defined in this study as a function of the amount of confining steel and concrete, distance between confining steel and the rebar and concrete segregation effect. It is proposed to adopt the same degradation rules used for well-confined concrete. These rules are validated through statistical tests for moderately confined concrete. They are found to predict correctly the main features of reduced envelope response under increasing cycling amplitudes but to underestimate response degradation under constant cycling limits for the subsequent cycles to the first cycle. To demonstrate the validity and limitations of the proposed model, its predictions under monotonic loading are compared with experimental results and analytical predictions from other studies.

A critical review of the effect of concrete composition on rebar–concrete interface (RCI) bond strength: A case study of nanoparticles

“…In order to confirm this hypothesis, normalized RC bond strength by compressive strength of mixtures ( ∕f c ) is illustrated in Fig. 15b for both NC and nano-concrete, which is a common way for ignoring effect of concrete compressive strength on RCI bond strength [21,48]. Results indicate that considerable deviation exists between nano ∕ NC from the ratio ∕f c nano ∕ ∕f c NC , especially for nano-clay, carbon nanotubes, and nano-silica ( Fig.…”

“…This can be attributed to the tensile stress in the compression steel rebar embedded in joints [18]. Accordingly, the bond-slip phenomenon changes the curvature distribution in the inelastic zone region at the girder ends [19][20][21]. In the case of crack pattern, increasing applied loading causes an increase in the depth of the cracks, while the steel rebar between the cracks continues to take the tension.…”

Micromechanical modeling of tension stiffening in FRP-strengthened concrete elements

“…The reinforcing bars-to-concrete bond behavior has been the subject of several numerical, analytical and experimental investigations in the literature. Different constitutive laws ranging from simple average bond-slip models to more sophisticated models that account for the effect of stress level, confinement, and concrete cracking have been proposed [38][39][40][41][42]. The bond-slip-strain model proposed in Shima et al [27] is selected in this study for the simulations.…”

Experimental and Numerical Study of Nano-Silica Additions on the Local Bond of Ultra-High Performance Concrete and Steel Reinforcing Bar

“…al. in their paper presented a summary of an experimental investigation and the derivation of a bond-slip model for reinforcing steel embedded in moderately confined concrete under monotonic and cyclic loadings [9]. Yan, C. and Mindes, S. (1994) conducted a bond test between epoxy-coated reinforcing bars and concrete under impact loading [10].…”