• Steel and Composite Structures
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• v.51 no.5
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• pp.529-543
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• 2024

The bonding efficacy of steel I-section embedded in metakaolin-fly ash-based geopolymer concrete (MK-FA-GC) was investigated in this study. Push-out tests were conducted on nine column specimens to evaluate the influence of compressive strength of concrete, embedded length of steel I-section, thickness of concrete cover, and stirrup ratio on the bond performance. Failure patterns, load-slip relationships, bond strength, and distribution of bond stress among the specimens were analyzed. The characteristic bond strength of geopolymer concrete (GC) increased with higher compressive strength, longer embedded steel section length, thicker concrete cover, and larger stirrup ratio. Empirical formulas for bond strength at the loading end were derived based on experimental data and a bond-slip constructive model for steel-reinforced MK-FA-GC was proposed. The calculated bond-slip curves showed good agreement with experimental results. Furthermore, numerical simulations using ABAQUS software were performed on column specimens by incorporating the suggested bond-slip relationship into connector elements to simulate the interface behavior between MK-FA-GC and the steel section. The simulation results showed a good correlation with the experimental findings.

• Computers and Concrete
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• v.23 no.3
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• pp.155-160
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• 2019

The use of recycled aggregate concrete for the purpose of environmental and resource conservation has gained increasing interest in construction engineering. Nevertheless, few studies have reported on the bonding performance of the bars in recycled aggregate concrete after exposed to high temperatures. In this paper, 72 pull-out specimens and 36 cubic specimens with different recycled coarse aggregate content (i.e., 0%, 50%,100%) were cast to evaluate the bond behavior between recycled aggregate concrete and steel bar after various temperatures ($20^{\circ}C$, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$). The results show that the recycled aggregate concrete pull-out specimens exhibited similar bond stress-slip curves at both ambient and high temperature. The bond strength declined gradually with the increase of the temperature. On the basis of a regression analysis of the experimental data, a revised bond strength mode and peak slip ratios relationship model were proposed to predict the post-heating bond-slip behavior between recycled aggregate concrete and steel bar.

• 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.

• Structural Engineering and Mechanics
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• v.81 no.2
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• pp.163-178
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• 2022

This paper aimed to study the local bond-slip behavior between ultra-high-performance concrete (UHPC) and a reinforcing bar after exposure to high temperatures. A series of pull-out tests were carried out on cubic specimens of size 150×150×150 mm with deformed steel bar embedded for a fixed length of three times the diameter of the tested deformed bar. The experimental results of the bond stress-slip relationship were compared with the Euro-International Concrete Committee (CEB-Comite Euro-International du Beton)-International Federation for Prestressing (FIP-Federation Internationale de la Precontrainte) Model Code and with prediction models found in the literature. In addition, based on the test results, an empirical model of the bond stress-slip relationship was proposed. The evaluation and comparison results showed that the modified CEB-FIP Model code 2010 proposed by Aslani and Samali for the local bond stress-slip relationship for UHPC after exposure to high temperatures was more conservative. In contrast, for both room temperature and after exposure to high temperatures, the modified CEB-FIP Model Code 2010 local bond stress-slip model for UHPC proposed in this study was able to predict the test results with reasonable accuracy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.157-158
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• 2017

This tests examined bond stress-slip relationship of V-ties embedded into concrete as a supplementary lateral reinforcement proposed for ductility of concrete flexural members. The different leg shapes of V-ties were prepared as a test parameter. The V-tie with pressed end-legs exhibited 28% higher bond strength than the conventional V-ties, whereas bond stress-slip curves were insignificantly affected by the embedment length of V-ties.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.215-218
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• 2003

To analyze a bond stress-slip behavior between a reinforcing bar and concrete under repeated loading, pull-out fatigue test was performed. Major variables were repeated stress levels and cycle numbers. Test specimen was taken repeated constant amplitude loading before it was fractured by pull-out test. Increments of bond strength and slip according to repeated stress level and cycle numbers were analyzed. On the basis of test results, Local bond stress-slip relationship under repeated loading were formulated

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.443-448
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• 2001

This paper presents a bond characteristics of high strength steel reinforced concrete members. High strength steel is what yield strength is higher than that of normal strength steel. So, the amount of flexural steel needed in R.C. members can be decreased. In result, it is expected that the workability and structure quality can improve and man power can minimize. For this purpose, specimens were made and tested with experimental parameters, such as concrete strength, steel diameter and yield strength. The result showed that under same tensile force of steel, in case of substituting normal strength steel with high strength steel, maximum bond stress increased and development length didn't almost change. In addition, the governing equation of bond and bond stress verse slip relationship were derived and compared with test values such as maximum bond stress, slip and bond stiffness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2279-2286
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• 2015

Recently it has been actively studied that the use of hybrid GFRP-concrete structure with dual purpose of both a permanent forwork and main tensile reinforcement of GFRP plank. In applying general analysis and design technique to evaluate the performance of hybrid structures with cast-in-place high strength concrete and GFRP plank, it is essential that the characteristics of the bond slip model is identified. In this study a simplified bilinear bond slip model for hybrid structure with GFRP plank and cast-in-place high strength concrete is proposed. Maximum average bond stress of simple bond slip relationship that has been proposed in this study is 3.29MPa, initial slope is 35.66MPa/mm, the total slip is 0.23mm and interfacial fracture energy is 0.37kN/m.

• Structural Engineering and Mechanics
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• v.7 no.4
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• pp.413-432
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• 1999

A macro-element model is developed to account for shear deformation and bond slip of reinforcement bars in the beam-column joint region of reinforced concrete structures. The joint region is idealized by two springs in series, one representing shear deformation and the other representing bond slip. The softened truss model theory is adopted to establish the shear force-shear deformation relationship and to determine the shear capacity of the joint. A detailed model for the bond slip of the reinforcing bars at the beam-column interface is presented. The proposed macro-element model of the joint is validated using available experimental data on beam-column connections representing exterior joints in ductile and nonductile frames.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.79-86
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• 2014

In this paper, a stress transfer mechanism between near surface-mounted (NSM) fiber reinforced polymer (FRP) plate and concrete was investigated and a reliable analytical procedure for it was presented by using bilinear bond-slip model simulating the bond behavior of NSM FRP plate. As a result, critical values in the bi-linear model such as maximum shear strength, slip at that time and failure slip at the initiation of softening de-bonding were suggested for being used in the differential equation considering he interfacial characteristic between NSM FRP and concrete. Also, it was found that the bond-slip behavior could be suitably redicted by using the proposed procedure even in the case of various bond lengths from the comparison with bond test result.