• Journal of Korean Association for Spatial Structures
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• v.22 no.4
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• pp.99-107
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• 2022

Existing reinforced concrete building structures constructed before 1988 have seismically-deficient reinforcing details, which can lead to the premature failure of the columns and beam-column joints. The premature failure was resulted from the inadequate bonding performance between the reinforcing bars and surrounding concrete on the main structural elements. This paper aims to quantify the bond-slip effect on the dynamic responses of reinforced concrete frame models using finite element analyses. The bond-slip behavior was modeled using an one-dimensional slide line model in LS-DYNA. The bond-slip models were varied with the bonding conditions and failure modes, and implemented to the well-validated finite element models. The dynamic responses of the frame models with the several bonding conditions were compared to the validated models reproducing the actual behavior. It verifies that the bond-slip effects significantly affected the dynamic responses of the reinforced concrete building structures.

• Magazine of the Korea Concrete Institute
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• v.6 no.4
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• pp.92-101
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• 1994

A new analytical model is proposed to better understand the transfer bond performance in a prestressed pretensioned concrete beam. The transfer length is divided into an elastic and a plas tic zones in this model. The bond stress is assumed t.o increase proportionally with the slip t.o the lirnit of maximum bond stress within the elastic zone and remains at a constant maximum value wthin the plastic zone. Four main stress patterns: bond stress, slip, steel stress, and concrete stress distributions within the transfer length are obtained precisely. The total transfer length al\ulcornerd free-end slip obtained here give a close comparison to the test results by Cousins et al.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.495-501
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• 2009

In this paper, a numerical anchor bond-slip model is proposed to improve the numerical simulation of concrete-steel structures connected with steel anchor bolts and subjected to extreme cyclic loading. The suggested bond-slip model is composed of a group of nonlinear uniaxial connector elements and its parameters can be determined by calibrating the model with pull-out test data. Numerical analysis results from simulating a concrete foundation-steel column structure using the proposed bond-slip anchor model, which is implemented based on Abaqus elements, and the perfect-bond anchor model are compared with the experimental results. It is concluded that a reasonable anchor bond-slip model is required to realistically simulate concrete-steel structures subjected to extreme cyclic loading, and the proposed anchor bond-slip model shows acceptable performance in the present numerical analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.309-312
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• 2006

An experimental study for bond slip behavior of concrete and a FRP plank was used as the both formwork and the tensile reinforcement for a concrete structural member is described. For the FRP plank and the concrete to act as a composite structural member a satisfactory bond at the interface between the smooth surface of the FRP and the concrete must be developed. This study focuses on investigation of the bond slip behavior of sand coated interface between FRP and cast-in-place concrete experimentally.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.853-858
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• 2003

A new method is proposed to obtain bond-slip model for an adhesive joint between FRP and concrete. Interface element, which can describe the bond behavior, is developed in order to overcome the restriction that complex constitutive relations cannot be modeled in analytic solution. Calibrating numerical bond-slip model to experimental results, multi-objective optimization problem is constructed by physical programming method, and is solved using genetic algorithm. The validity of proposed method is demonstrated by comparing known analytic solution and numerically optimized solution.

• Structural Engineering and Mechanics
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• v.74 no.5
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• pp.589-600
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• 2020

The bonding interface of the concrete slab track and cement-asphalt mortar layer plays an important role in transferring load and restraining the track slab's deformation for slab track structures without concrete bollards in high-speed railway. However, the interfacial bond-slip behavior is seldom considered in the structural analysis; no credible constitutive model has been presented until now. Elaborating the field tests of concrete to cement-asphalt mortar interface subjected to longitudinal and transverse shear loads, this paper revealed its bond capacity and failure characteristics. Interfacial fractures all happen on the contact surface of the concrete track slab and mortar-layer in the experiments. Aiming at this failure mechanism, an interfacial mechanical model that employed the bilinear local bond-slip law was established. Then, the interfacial shear stresses of different loading stages and the load-displacement response were derived. By ensuring that the theoretical load-displacement curve is consistent with the experiment result, an interfacial bond-slip constitutive model including its the corresponding parameters was proposed in this paper. Additionally, a finite element model was used to validate this constitutive model further. The constitutive model presented in this paper can be used to describe the real interfacial bonding effect of slab track structures with similar materials under shear loads.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.569-589
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• 2007

This paper presents an analytical model for RC beam-column connections that takes into account bond deterioration between reinforcing steel and concrete. The model is based on the Lumped Damage Mechanics (LDM) theory which allows for the characterization of cracking, degradation and yielding, and is extended in this paper by the inclusion of the slip effect as observed in those connections. Slip is assumed to be lumped at inelastic hinges. Thus, the concept of "slip hinge", based on the Coulomb friction plasticity theory, is formulated. The influence of cracking on the slip behavior is taken into account by using two concepts of LDM: the effective moment on an inelastic hinge and the strain equivalence hypothesis. The model is particularly suitable for wide beam-column connections for which bond deterioration dominates the hysteretic response. The model was evaluated by the numerical simulation of five tests reported in the literature. It is found that the model reproduces closely the observed behavior.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.917-922
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• 2002

This paper deals with the estimation of the maximum crack widths considering bond-slip relationships based on experimental data that were tensed by axial force. It is certificated that the concrete stress condition clearly affects the bond-slip relationship. The proposed method utilizes the conventional crack and bond-slip theories as well as the characteristics of deformed reinforcement and size effects. An analytical equation for the estimation of the maximum flexural crack width is formulated as a function of minimum crack length and the coefficient of bond stress effect. The validity, accuracy and efficiency of the proposed method are established by comparing the analytical results with the experimental data and the major specifications (e.g., ACI, CEB-FIP Model code, Turocode 2, JSCE, etc.). The analytical results presented in this paper indicate that the proposed method can be effectively estimated the maximum flexural crack width of reinforced concrete.

• Computers and Concrete
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• v.19 no.6
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• pp.625-630
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• 2017

In this paper, 54 pull-out specimens and 36 cubic specimens with different replacement ratios of fly ash in the concrete (i.e., 0%, 20%, 30%, 40%, 50%, 60%) were fabricated to evaluate the bond at the interface between fly ash concrete and steel rebar. The results showed that the general shape of the bond-slip curve between fly ash concrete and steel rebar was similar to that for the normal concrete and steel rebar. The bond strength between fly ash concrete and the steel rebar was closer to each other at the same rebar diameter, irrespective of the fly ash replacement percentage. On the basis of a regression analysis of the experimental data, a revised bond strength mode and bond-slip relationship model were proposed to predict the bond-slip behaviour of high volume fly ash concrete and steel rebar.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.285-292
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• 2006

In this study, a method determining the local bond-slip model from pure shear test results of CFRP sheet-concrete adhesive joints is proposed and local bond-slip models are presented. Adhesive joints with a specific bond-slip model, which is assumed as multi-linear curve in order to represent arbitary function, are solved numerically. The difference between the solution and test results are minimized for finding the bond-slip model. The model with bilinear curve is also optimized to verify the improvement of multi-linear model. The selected test results are ultimate load-adhesive length curves from a series of adhesive joints and load-displacement curves for each joint. The optimization problem is formulated by physical programming, and the optimized bond-slip model is found using genetic algorithm.