scholarly journals Mesoscale modelling of bond failure behavior of ribbed steel bar and concrete interface

2019 ◽  
Vol 49 (4) ◽  
pp. 445-454
Author(s):  
Liu JIN ◽  
MengJia LIU ◽  
JingQi HUANG ◽  
XiuLi DU
Keyword(s):  
Failure Behavior ◽  
Mesoscale Modelling ◽  
Bond Failure ◽  
Steel Bar ◽  
Concrete Interface

scholarly journals Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1251
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Xiangtian Xu ◽  
Yanjun Shen ◽  
Hailiang Jia ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Concrete Structures ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Steel Bar ◽  
Concrete Interface

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

Electrochemical Studies on the Corrosion of Steel Bar in Concrete in Chloride Environment

2013 ◽  
Vol 631-632 ◽  
pp. 776-781
Author(s):  
Rui Jin Zhang ◽  
Hui Lin Yang ◽  
Da Yong Ye
Keyword(s):  
Electrochemical Impedance ◽  
Interface Quality ◽  
Linear Polarization Resistance ◽  
Corrosion Initiation ◽  
Impedance Response ◽  
Steel Bar ◽  
Chloride Environment ◽  
Corrosion Of Steel ◽  
Concrete Interface

This paper deals with the influence of the steel-concrete interface quality on the steel bar corrosion. Electrochemical methods including linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) were comparatively used to monitor the corrosion process of reinforcing steel in cement mortar. Experimental results show that a good quality of steel-concrete interface can significantly delay the corrosion initiation and reduces the corrosion rate. The results highlight the reasonable correlation between the impedance response and the Rp values by LPR method, but the corrosion rates obtained by EIS are lower than those results of LPR.

Microstructure Analysis of the Rust Developing at Steel-Concrete Interface

2008 ◽  
Vol 400-402 ◽  
pp. 215-220
Author(s):  
Rong Zhen Dong ◽  
Jun Wei ◽  
Xi Wu Zhou
Keyword(s):  
Iron Oxidation ◽  
Concrete Cover ◽  
Forming Process ◽  
Final State ◽  
Steel Bar ◽  
Galvanostatic Method ◽  
Hematite Fe2o3 ◽  
Distribution Composition ◽  
Corrosion Of Steel ◽  
Concrete Interface

The rust distribution and the crack expansion in the deteriorated concrete were studied through the macroscopic and microcosmic method. The results show that the corrosion of steel bar in the concrete is non-uniform even though by Galvanostatic Method. The crack appears earlier and expands quicker at the thin concrete cover than others side and the short crack filled by the rust is found near by the steel bar and converges the main crack. The distribution, composition and the developing of the rust at steel-concrete interface were studied by the microscopic methods of BSE, EDAX and Raman Microscope. By these methods, the rust distributes inhomogeneous and the ion element area was divided into zones evidently. From concrete to steel bar, the rust in turn is: initial rust zone, the mixture area of the rust and mortar about 20-50 μm in width and main containing the goethite (FeOOH); the secondary rust zone, high density area of ion element and about 10-20μm in width and being the mixture of hematite（Fe2O3）and magnetite(Fe3O4); the final rust zone, similar as the initial rust and being the mixture of hematite(Fe2O3)and goethite(FeOOH). According to the electrochemistry principle, the forming process of rust does not follow the iron oxidation procedure entirely but form middle production under the special situation of the condition interior concrete and the electric field outside. The extrusion action of concrete around steel bar makes the rust compressed and metamorphic and the secondary rust forming. So the process and the final state of this special corrosion production are the key parameters leading to the deterioration of concrete.

scholarly journals Flexural Behavior of Concrete Beam Strengthened by Near-Surface Mounted CFRP Reinforcement Using Equivalent Section Model

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Woo-tai Jung ◽  
Jong-sup Park ◽  
Jae-yoon Kang ◽  
Moon-seoung Keum
Keyword(s):  
Cross Sections ◽  
Failure Criteria ◽  
Flexural Behavior ◽  
Failure Behavior ◽  
Failure Model ◽  
Bond Failure ◽  
Near Surface ◽  
Near Surface Mounted ◽  
Section Model ◽  
Sectional Shape

FRP (fiber reinforced polymer) has found wide applications as an alternative to steel rebar not only for the repair and strengthening of existing structures but also for the erection of new structures. Near-surface mounted (NSM) strengthening was introduced as an alternative of externally bonded reinforcement (EBR) but this method also experiences early bond failure, which stresses the importance of predicting accurately the bond failure behavior in order to evaluate precisely the performance of NSM reinforcement. This study proposes the equivalent section model assuming monolithic behavior of the filler and CFRP reinforcement. This equivalent section model enables establishing a bond failure model applicable independently of the sectional shape of the CFRP reinforcement. This so-derived bond failure model is then validated experimentally by means of beams flexure-strengthened by NSM CFRP reinforcements with various cross-sections. Finally, analytical analysis applying the bond failure model considering the equivalent section and defined failure criteria is performed. The results show the accuracy of the prediction of the failure mode as well as the accurate prediction of the experimental results regardless of the sectional shape of the CFRP reinforcement.

scholarly journals An Experimental Study of Bond Behavior of Micro Steel Fibers Added Self-compacting Concrete with Steel Reinforcement

2020 ◽  
Author(s):  
Abdul Salam ◽  
Shah Room ◽  
Shahid Iqbal ◽  
Khalid Mahmood ◽  
Qaiser Iqbal
Keyword(s):  
Bond Strength ◽  
Steel Fibers ◽  
Self Compacting Concrete ◽  
Bond Failure ◽  
Maximum Increase ◽  
Bond Behavior ◽  
Micro Cracks ◽  
Steel Bar ◽  
Experimental Values ◽  
Major Emphasis

The obstruction offered by the surrounding concrete to the pulling out of embedded steel bar is known as bond strength. Steel fibers addition to concrete improves its bond strength by arresting the cracks due to their bridging effect. Bond failure occurs when cracks in the surrounding concrete initiates, providing enough space for bar to be pulled-out. Micro steel fibers efficiently control the formation of micro cracks and may improve bond strength to a greater extent compared to the longer steel fibers. However, it reduces the workability of concrete which is of greater importance in case of self-compacting concrete (SCC). Reduction of workability is less pronounced when straight micro steel fibers are used due to their shorter lengths and straight geometry. Thus, different amount of straight micro steel fibers (0.25 %, 0.5 %, 0.75 %) were incorporated in to SCC to investigate their fresh and mechanical properties with major emphasis on the bond strength. Results indicate that steel fibers addition to SCC improve the splitting tensile strength and bond strength significantly with a maximum increase of 33.5 % and 54.9 % respectively with 0.75 % fibers addition. An equation is proposed for the calculation of bond strength with micro steel fibers addition to SCC with a maximum variation of 4 % to those of experimental values.

Beam Test Research on Bond Behavior between Steel Bar and Concrete in Salt-Frost Environment

2011 ◽  
Vol 261-263 ◽  
pp. 50-55
Author(s):  
Gang Xu ◽  
Tian Cheng Ai ◽  
Qing Wang ◽  
Jiang Bo Huang
Keyword(s):  
Bond Strength ◽  
Concrete Beam ◽  
Saline Solution ◽  
Freezing And Thawing ◽  
Bond Failure ◽  
Actual Structure ◽  
Bond Behavior ◽  
Steel Bar ◽  
Bond Property ◽  
Freezing And Thawing Cycles

Salt-frost action is one of the main causes that induced the decrease of force resistance behavior of concrete structure in cold areas. By the freezing and thawing cycles of 0, 50, 100 and 200 times for the reinforcement concrete beam specimens in saline solution, the effects of freezing and thawing cycles on the bond behavior between steel bar and concrete are studied. The results show that: with the increase of freezing and thawing cycles, the bond strength and the bond stiffness trend to degenerate. The co-operating capacity between steel bar and concrete falls down. The ductility of the specimens reduces, and the bond failure presents brittle. The degradation speed of bond strength after salt-frosting is relevant to the size and stirrup ratio of specimens, the larger the specimen’s size is, and the higher the stirrup ratio is, The stronger the capacity of resisting freezing-thawing cycle is, the more slowly the bond property degenerate, the study using small specimens will probably underestimate the frost resistance of actual structure.

scholarly journals Mesoscale modelling of bond failure behaviour of ribbed steel bar and concrete interface

2021 ◽  
Vol 272 ◽  
pp. 02003
Author(s):  
Mengjia Liu ◽  
Renbo Zhang ◽  
Liu Jin ◽  
Xiuli Du
Keyword(s):  
Frictional Resistance ◽  
Surface Characteristics ◽  
Bond Stress ◽  
Scale Model ◽  
Analysis Method ◽  
Bond Failure ◽  
Bond Behaviour ◽  
Steel Bar ◽  
Friction Component ◽  
Good Agreement

To explore the nonlinear bond behaviour between ribbed bar and concrete, combined with the characteristics of concrete meso-structure and ribbed bar surface characteristics and considering frictional resistance and the mechanical interlocking between rebar and concrete, a meso-scale model is established. Based on the good agreement between the simulation results and experimental results, the failure mechanism of bond between rebar and concrete is discussed, and the distribution characteristics of bond stress of steel bar are analysed. Furthermore, based on the meso numerical analysis method, the influence of friction coefficient between rebar and concrete on the failure mode of concrete and bond stress-slip curve was discussed, and the proportion of friction component in bond strength is obtained.

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