Bond-slip Constitutive Relation Research Articles

Bond performance of recycled coarse aggregate concrete with rebar under freeze–thaw environment: A review

Abstract In this article, a review focusing on the frost resistance of recycled coarse aggregate concrete (RAC) and the bond performance of RAC with rebar under freeze–thaw environment is carried out. The results show that there are still some controversies about the advantages and disadvantages of the frost resistance of RAC, and many influencing factors have not been considered. The mass of the RAC pullout specimens shows a trend of first increasing and then decreasing after freeze‒thaw cycles. The failure modes of the RAC pullout specimens after freeze‒thaw cycles include pullout failure, pullout-splitting failure, splitting failure, and rebar yielding failure. The bond performance of RAC with rebar shows a degradation trend after freeze‒thaw cycles, mainly in the decrease in bond strength and the increase in bond slip. The bond performance of RAC specimens is inferior to that of natural aggregate concrete specimens after freeze‒thaw cycles. The bond strength prediction models and the bond–slip constitutive relation prediction models of RAC with rebar after freeze‒thaw cycles have been summarized to ensure that engineers can better understand their applicability. The bond stress distribution between the RAC and rebar in the anchoring area is not uniform and constantly changes with the number of freeze‒thaw cycles. The degradation mechanism of the bond performance of RAC with rebar after freeze‒thaw cycles is analyzed.

Tensile performance of UHPC-filled grouted corrugated duct connection for large-diameter rebars in prefabricated canopies

Grouted corrugated duct connection (GCDC) is an effective connection method for prefabricated structures. To facilitate the use of large-diameter rebars with short anchorage length in prefabricated canopies on the railway platform, a novel Ultra High-Performance Concrete (UHPC)-filled grouted corrugated duct connection (UGCDC) was proposed. Tensile experiments were conducted on specimens using the anchorage length, the grouting material type, and the rebar diameter as research parameters to evaluate the tensile performance of UGCDC. The influence of parameters on bearing capacities, failure modes, rebar strains, and corrugated duct strains was compared and analyzed to reveal the force transmission mechanism of the UGCDC. Combining experimental results and theoretical analysis, a simplified equation for predicting tensile bearing capacity of UGCDC was developed, and a normalized bond-slip constitutive relation model of UGCDC was proposed. The results indicate that UHPC can reduce the anchorage length of rebar due to its superior mechanical properties, and the large-diameter (25 mm) rebar requires a critical anchorage length with 10d. The proposed model can predict the bond-slip constitutive relation of UGCDC accurately. Finally, a finite element model considering the bond-slip effect was established by using the normalized bond-slip model, which can accurately predict the force-displacement curve and failure mode of UGCDC. Finally, a parameter analysis was conducted to analyze the impact of rebar position and adjacent of surrounding rebars on the tensile performance of UGCDC.

Beam-type experimental study on interfacial bond-slip behavior of steel reinforcement recycled concrete

Four steel reinforcement recycled concrete (SRRC) specimens were designed and tested to investigate the bond behavior at the interface between steel and recycled concrete. The parameters of test is the replacement ratio of recycled coarse aggregate. The results show that bond-slip failure occurred in all the specimens (except SRRC-B01), and the ultimate bearing capacity of the specimens increased at first and then decreased with the increase of the replacement ratio of recycled coarse aggregate. When the replacement ratio is 70%, the ultimate bearing capacity is largest, which is about 19.2% higher than that replacement ratio is 0, and about 7% higher than that replacement ratio is 100%. The interfacial bond strength of steel and recycled concrete increase at first and then decreased with the increase of replacement ratio, and the law of slip at loading end is similar to bond strength, they all reach the maximum value when the replacement ratio is 70%. According to the analysis of the test results, the calculation formulas of bond strength and slip at loading end with the consideration of replacement ratio of recycled coarse aggregate were proposed, and the accuracy of the formulas is verified by comparing with the test data. Finally, the bond-slip constitutive relation at the interface between steel and recycled concrete was established, and a segmented representation model was proposed. The fitted values are in good agreement with the test values. The investigation of this paper can provide reference for relevant scientific research and engineering design.

Bond behavior between recycled aggregate concrete and steel rebar subjected to biaxial lateral pressure

Eighty-four pull-out tests were carried out to study the bond behavior between recycled aggregate concrete (RAC) and steel rebar, considering different levels of recycled coarse aggregate (RA) substitution and biaxial lateral pressure. The effects of these two parameters on bond strength and peak slip were analyzed, the bond-slip constitutive relation between RAC and steel rebar under biaxial lateral pressure was established, and the energy of bonded interface was also analyzed. The results show that the failure patterns of specimens without lateral pressure were splitting failure, while the failure patterns of specimens with different biaxial lateral pressure can be classified as splitting-pull out failure. With an increase of lateral pressure, the relative bond strength, peak slip and bond energy gradually increased, whereas the relationship between RA replacement percentages and these parameters could not be clearly observed. In addition, the relative bond strength and peak slip approximately increased linearly with the increase of lateral pressure. Finally, based on the experimental results, a modified expression for bond-slip prediction was developed, taking into account damage, and the obtained results show that the predicted curves fit well with test data.

Study on the bond behavior between steel bar with different derusting methods and concrete

In this paper, three different derusting methods: angle grinder, rust remover and shot blasting machine were selected to remove the corrosion products on the surface of steel bars with different corrosion ratios. The bond behavior between steel bars and concrete after different derusting methods was experimentally studied. To carry out this study, deformed steel bars with diameters of 14 mm, 18 mm, 22 mm and 25 mm were selected to conduct corrosion in the natural environment and 36 center-pulled specimens were cast. The following contents were studied during the test: (1) the weakening of the surface rib height of steel bar after various derusting methods; (2) the effects of derusting methods, corrosion ratio and steel bar diameter on the bond strength and peak slip were studied, the influence mechanism of various factors on the bond performance of specimens was revealed, and the influence law of various factors on the bond performance of specimens was summarized; (3) the bond-slip constitutive relation between steel bar and concrete with different diameters after different derusting methods were studied.

Study on Dynamic Bond-Slip Constitutive Relation of Corroded Mortar Anchor

Study on Dynamic Bond-Slip Constitutive Relation of Corroded Mortar Anchor

Finite Element Analysis on Steel-Concrete Composite Beams Considering the Bond-Slip Effect on the Interface

In order to accurately simulate the bond-slip performance of steel-concrete composite beams, a trilinear stress-strain relation model was adopted to simulate the mechanical properties of steel. A uniaxial stress-strain relation curve was used to study the nonlinear mechanical behaviors of concrete. The resisting shear effects of studs and concrete in the bonding area were equivalent to nonlinear springs. Based on the energy principle, a calculation method of the interfacial bond stiffness of steel-concrete composite beams was proposed and the interfacial bond-slip constitutive relation of steel-concrete composite beams was given. Based on it, the three-dimensional finite element analysis model of steel-concrete composite beams was established by the finite element analysis software ANSYS, and the numerical simulations of existing push-out tests of composite beams were performed. By comparison, it can be seen that the results from finite element analysis in this paper are close to the experimental ones. It indicated that the finite element analysis model can accurately simulate the bond-slip action of the interface, and this model can be applied to the numerical calculation and analysis of steel-concrete composite beams.

Bond behavior between BFRP bar and basalt fiber reinforced seawater sea-sand recycled aggregate concrete

In order to meet the demand of construction waste treatment and using local materials, the use of recycled coarse aggregate (RCA), sea-sand and seawater is of great significance to coastal areas and sea-related engineering construction. Basalt fiber (BF) reinforced seawater sea-sand recycled aggregate concrete (BFSSRAC) with good workability was prepared in this paper. The mechanical properties of BFSSRAC and bond behavior between BFRP bar and BFSSRAC were investigated considering the effects of BF content and concrete strength through a series of tests and microstructure analysis. The results showed that the combination use of BF, seawater, sea-sand and RCA could reduce the adverse effects of RCA on the mechanical property of concrete. SEM analysis showed that the addition of BF could effectively improve the pore structure of concrete matrix, especially the interfacial transition zone (ITZ). The usage of RCA reduced the bond strength between BFRP bar and RAC, while the usage of seawater and sea-sand had little effect on the bond-slip constitutive relation. After adding BF, the ultimate bond strength and maximum slip of BFSSRAC were larger than those of concrete without fibers and increased with the increasing BF content. Based on the experimentally obtained τ-s curves, the bond-slip constitutive relation model between BFRP bar and BFSSRAC was proposed, and the model was verified by deviation analysis between calculated and measured values. The findings of this study can provide new and meaningful reference for the application of BFSSRAC structures reinforced with BFRP bars.

Study on mechanical properties of SMA silk

Bond-slip constitutive relation between shape memory alloy wires and concrete is a comprehensive reflection of the bonding properties and it is relevant to crack width, plastic hinge rotation capacity, shear failure and theory analysis of nonlinear finite element. It has important significance of the numerical model of bond-slip of shape memory alloy concrete structure to the theoretical analysis and actual design. However, it is still in the exploratory stage of the constitutive relation between these two materials at home and abroad. This paper made the following research: Mechanics performance test of SMA. Differential scanning calorimetry test were used to get the heat transfer rate and temperature relationship diagram of the SMA wires, so the phase transition temperature of SMA was determined. On the basis of this, pull-out test was carried on to know the mechanical properties of the SMA wires.

Bond–slip constitutive relation of mortar anchor under different loading rates

Purpose This paper aims to focus on establishing the bond-slip constitutive relation of mortar anchor under high loading rates by the dynamic pull-out test. Design/methodology/approach Self-made specimens were made for the dynamic pull-out test to explore the bond performance of mortar anchor, and the bond-slip constitutive relation of mortar anchor under high loading rates was established according to the analysis of test data. Findings During the loading process, the position of the peak bond stress was observed to translate to the free end. The bearing capacity of the mortar anchor was enhanced to some extent due to the increase of the loading rate. Originality/value The bond-slip constitutive relation of mortar anchor under high loading rates was established with the introduction of the position function and dynamic-load expanded coefficient.

Flexural behavior investigation of steel-GFRP hybrid-reinforced concrete beams based on experimental and numerical methods

Due to their superior corrosion resistance and strength-to-weight ratio, GFRP (glass fiber reinforced polymer) rebar are widely used as reinforcement for concrete structures, but the brittleness of GFRP and their inferior bonding performance with concrete needs to be addressed. Hybrid reinforcement is a strategy to address the brittleness of GFRP rebar, but the inferior bonding performance may cause inaccuracy in the performance prediction. To determine the effects of bonding performance on the flexural behavior of GFRP- and hybrid-reinforced concrete beams and compare their flexural behaviors, both types of beams were prepared and subjected to four-point bending tests in this research. Their flexural capacities from the experimental results were then compared with the theoretical results. Additionally, the bond-slip relation between the GFRP rebars and concrete was obtained by means of pull-out tests, and an FE model based of the bond-slip results was developed to simulate the flexural behavior of the beams. From the experimental results, the hybrid reinforcement was shown to be able to control the beginning of cracking and reduce the maximum crack width by over 50% in concrete compared that of to GFRP reinforcement at the same load level. The flexural behavior of the hybrid-reinforced beam can be accurately predicted by the theoretical and FE methods. For the GFRP-reinforced beams, the theoretical method overestimates the flexural capacity by 9%; according to the results from the FE simulation, inclusion of the nonlinear bond-slip constitutive relation between the GFRP rebar and concrete helps to mitigate the underestimation of the mid-span deflection from 14.4% to 2.1%.

Study on the interfacial bond slip constitutive relation of I-section steel and fully recycled aggregate concrete

17 standard push-out specimens which are designed to study the interfacial bond-slip behavior of I-section steel and reinforced recycled concrete with 100% replacement ratio of coarse aggregate (SRRC). The parameters of test are strength of recycled aggregate concrete, thickness of I-section steel protective layer, embedded length of I-section steel and ratio of stirrups. The test results show that the strain and stress of the I-section steel at the interface of SRRC distribute exponentially, and the four test parameters have a certain influence on the interfacial bond strength of SRRC. Based on the analysis of the test data, the calculation formulas of the interfacial bond strength of SRRC are established. The constitutive relations of the bond-slip at the loading end are established, and the multistage linear results are more satisfied with the test results than power-type. Finally, the position function of the bond-slip F(x) and the bond stress G(x) are introduced, and the bond-slip constitutive relation with changes of position are established, which provides a reference for related specification design and engineering construction.

Meso-scale analysis on shear failure characteristics of asphalt–aggregate interface

The bonding properties of asphalt–aggregate interface affect failure behaviors of asphalt mixtures. The objective of this study was to explore the shear failure characteristics of asphalt–aggregate interface by researching the interface shear strength and the continuous shear failure process. First, the oblique shear tests were conducted to investigate the interface shear strength under the influences of surface roughness, binder aging, loading rate, and aggregate type. Second, the direct shear tests were implemented to explore the continuous failure characteristics of the interface in terms of load–displacement curves. The interface bond-slip constitutive relation was established as a piecewise linear cohesive zone model. Finally, the grey relational analysis (GRA) was conducted to identify and prioritize the correlation between the applied experimental conditions and the interface bond-slip model parameters. The study results indicate that the improvement of surface roughness and loading rate could induce higher interface shear strength and a basalt aggregate with less silica has greater resistance to interface shear damage than a granite aggregate due to its stronger adhesion to binder. The interface shear resistance energy could benefit from higher surface roughness and normal stress level. Although binder aging could increase the interface shear strength, it imposes an adverse impact on the interface shear resistance energy. The established bond-slip constitutive model of the asphalt–aggregate interface could represent a three-stage evolutionary process of the interface shear failure. By performing the GRA, the binder aging condition would be the most significant factor affecting the interface shear performance when compared with the surface roughness and the normal stress.

Bond-slip constitutive relation between BFRP bar and basalt fiber recycled-aggregate concrete

In order to investigate the bond stress-slip constitutive relation between BFRP bar and basalt fiber recycled-aggregate concrete, 81 central pullout specimens were tested. Basalt fiber volume percent, fiber length and concrete strength grade were considered to be experimental variables to obtain the bond stress-slip curves. The results showed that adding basalt fiber into recycled-aggregate concrete will reduce the bond stress between BFRP bar and recycled-aggregate concrete but enhance the ductility of bond property; the bond stress increases with the increasing of fiber length and concrete strength grade. The bond stress-slip constitutive model was proposed and the results showed that the model is good in effect of fitting. The constitutive model can reflect the bonding mechanism between BFRP bar and basalt fiber concrete well, it also can provide reference for theoretical analysis and engineering applications of the bond and anchor property between BFRP bars strengthened recycled concrete.

Coarse Aggregate Replacement Ratio on the Properties of Recycled Concrete Bonding Effect

Through a pull-out test was designed. The load-slip curves between recycled concrete with different recycled coarse aggregate replacement percentage and rebar were recorded. This article studied the impact of different recycled aggregate replacement rate and the anchorage length for the bond strength between the recycled aggregate concrete and reinforced, and provided a beneficial reference for engineering design of recycled concrete structure under similar conditions. Determined the recycled concrete and reinforced the bond-slip constitutive relation. Come to the bonding properties of reinforced recycled concrete with recycled aggregate rate increase gradually decreased in the anchorage length sufficient to meet the design requirements, performance depended on the pull-out strength of reinforced recycled concrete and reinforced the bond.

Bond-Slip Constitutive Relationships of the CFRP/Concrete Interface

In consideration of the light weight, high strength, corrosion resistance and construction is convenient of carbon fiber reinforced polymer (CFRP), using CFRP to strengthen structure is becoming more and more widely. However, there is no commonly accepted understanding of the constitutive relationship of the bonding shear stress and slip between concrete and CFRP bonded interface, especially the decline of the constitutive relation is more difficult to measure accurately. An aim of this paper is to improve the experiment to explore bond stress and slip (τδ) constitutive relation of the bonding interface, strive for the experiment to measure the τδ constitutive relation curve of CFRP-concrete interface. Double pull test was proposed with the improved specimen, using the horizontal load, eliminate additional bending moment influence and improve the experimental accuracy. 17 specimens were tested to measure the τδ curves, according to the features of the constitutive relation curves, the mechanical characteristics of the bonding interface was further analysised.

Experimental Study on Bond-Slip Constitutive Relation between CFL and Concrete

Externally bonded reinforcing technique with fiber reinforced polymer (FRP) has been widely used in civil engineering. The performance of the interface between FRP and concrete is one of the key factors affecting the behavior of the strengthened structures. This paper presents a detailed study on the bond-slip mechanism between carbon fiber laminate (CFL) and concrete based on double-shear tests. 8 specimens with different bonded length and width of CFL were tested under static loading. Strain gauges along the CFL face and displacement sensor were used to measure longitudinal strains and slip of the interface. The bond-slip constitutive relation of the interface between CFL and concrete was analyzed with the testing results. Compared with four different bond-slip models, a shear stress-slip model was proposed based on the experimental data.

CFRP-混凝土界面粘结滑移本构关系试验研究

鉴于碳纤维复合材料(CFRP)的轻质高强、耐腐蚀、施工方便等特点，使用CFRP对结构进行维修加固也越来越广泛。然而，混凝土与CFRP粘结界面的粘结剪应力与滑移之间的本构关系却还没有形成统一的认识，尤其是本构关系的下降段更是难以准确测量出来。本文在于改进方法下实验探究粘结界面的粘结应力–滑移(τ-δ)本构关系，争取实验测出CFRP-混凝土界面的τ-δ本构关系全曲线。试验采用改进的双拉试件，采用水平加载，排除附加弯矩影响，提高实验结准确性。实测17个试件的CFRP界面τ-δ本构关系曲线，根据τ-δ本构关系曲线特性，分析粘结面受力特点。 In view of the light weight, high strength, corrosion resistance and convenient construction of carbon fiber reinforced polymer (CFRP), using CFRP to strengthen structure is becoming more and more widely. However, there is no commonly accepted understanding of the constitutive relationship of the bonding shear stress and slip between con-crete and CFRP bonded interface; especially the decline of the constitutive relation is more difficult to measure accu-rately. The aim of this paper is to improve the experiment to explore bond stress and slip (τ-δ) constitutive relation of the bonding interface, making sure that the experiment can measure the τ-δ constitutive relation curve of CFRP-concrete interface. Double pull test was adopted with the improved specimen, using the horizontal load, to eliminate additional bending moment influence and improve the experimental accuracy. 17 specimens were tested to measure the τ-δ curves. According to the features of the constitutive relation curves, the mechanical characteristics of the bonding interface were further analyzed.

Finite Element Analysis of the Pull-Out Specimens of Steel Reinforced Lightweight Concrete

Finite element analysis method of steel reinforced lightweight concrete pull-out specimens is exploded based on the test results. Spring element and local bond slip constitutive relation are introduced in analysis so as to consider the interfacial bond-slip between steel and lightweight concrete. Element tributary area and flange or web position should be taken into account in order to confirm the spring element real constant. Analysis results indicate that specimens bearing capacity and deformation can be well simulated adopting the stated method and constitutive relationship.

Research of Bond-Slip Constitutive Relation Model between Fiber Gypsum Board and Concrete Materials

How to establish the bond-slip constitutive relation model of concrete and gypsum board will be of great academic significance. Through the pull-out experiment of CFFP, the load-slip curves is obtained. The characteristics and research situation of bond-slip performance at the inter face of concrete and other materials are introduced, and the bond-slip constitutive relation models are summarized at the same time. By using the fitting operation, the proposed constitutive relation is put forward , which is feasible and can be applied to further research on CFFP.