scholarly journals Modeling of Cover Concrete Cracking Due to Uniform Corrosion of Reinforcement

2021 ◽  
Vol 12 (1) ◽  
pp. 43-49
Author(s):  
Sheikh Shakib ◽  
Abu Zakir Morshed
Keyword(s):  
Tensile Strength ◽  
Concrete Cover ◽  
Uniform Corrosion ◽  
Crack Initiation And Propagation ◽  
Rc Structures ◽  
Material Parameters ◽  
Cover Concrete ◽  
Initiation And Propagation ◽  
Cover Thickness ◽  
Bar Diameter

Cracking of cover concrete due to the corrosion of reinforcing steel is one of the main causes of deterioration in Reinforced Concrete (RC) structures. An outbound stress is developed in concrete surrounding the reinforcing steels due to the expansive corrosion products of reinforcement leading to cracking of the concrete cover. In this paper, the cracking pressure was simulated through a finite element modeling. The effect of geometrical and material parameters, i.e. concrete cover thickness, bar diameter, and concrete tensile strength, on the cracking pressure was also investigated. Abaqus 6.14 was used as modeling platform. The cracking pressure was found to dependent on the cover thickness and tensile strength of concrete. A higher pressure was required to initiate crack for a higher cover thicknesses and tensile strength. The cracking pressure was decreased with the increase in bar diameter. Finally the crack initiation and propagation has been simulated successfully for different arrangements of reinforcements. Journal of Engineering Science 12(1), 2021, 43-49

Experimental Test of Corrosion-Induced Concrete Cover Cracking Pattern

2011 ◽  
Vol 374-377 ◽  
pp. 1969-1973
Author(s):  
Di Tao Niu ◽  
Hua Song
Keyword(s):  
Scientific Basis ◽  
Concrete Cover ◽  
Accelerated Corrosion ◽  
Cover Concrete ◽  
Cover Cracking ◽  
Durability Assessment ◽  
Accelerated Corrosion Test ◽  
Cracking Pattern ◽  
Cover Thickness ◽  
Longitudinal Cracks

The study of cover cracking pattern can provide scientific basis for the durability assessment and maintanence of concrete structures. In this paper, corrosion induced cover cracking pattern was investigated by accelerated corrosion test. The cover thickness c, bar diameter d and bar spacing s were considered in the test. Test results showed that the cracking pattern of cover concrete mainly included four typies, that is longitudinal cracks including wedge and vertical, parallel cracks, spalling and delamination. When the bar spacing was small enough, the delamination of cover concrete occurred which had nothing to do with the ratio c/d. When c/d≤1, the corrosion of side bar mainly induced the vertical cracks and the corrosion of corner bar induced both vertical and wedge cracks. While c/d>1, the corrosion of corner bar mainly induced wedge cracks.

scholarly journals Concrete Protective Layer Cracking Caused by Non-Uniform Corrosion of Reinforcements

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4245 ◽  
Author(s):  
Lu Zhang ◽  
Ditao Niu ◽  
Bo Wen ◽  
Daming Luo
Keyword(s):  
Radial Displacement ◽  
Concrete Strength ◽  
Protective Layer ◽  
Concrete Cover ◽  
Uniform Corrosion ◽  
Reinforcement Corrosion ◽  
Concrete Cracking ◽  
Principal Tensile Stress ◽  
Cover Thickness ◽  
Corrosion Of Steel

The volume expansion of reinforcement corrosion products resulting from the corrosion of steel reinforcement embedded into concrete causes the concrete’s protective layer to crack or spall, reducing the durability of the concrete structure. Thus, it is necessary to analyze concrete cracking caused by reinforcement corrosion. This study focused on the occurrence of non-uniform reinforcement corrosion in a natural environment. The characteristics of the rust layer were used to deduce the unequal radial displacement distribution function of concrete around both angular and non-angular bars. Additionally, the relationship between the corrosion ratio and the radial displacement of the concrete around the bar was established quantitatively. Concrete cracking due to the non-uniform corrosion of reinforcements was simulated using steel bars embedded in concrete that were of uneven displacement because of rust expansion. The distribution of the principal tensile stress around the bar was examined. A formula for calculating the critical radial displacement at the point when cracking began was obtained and used to predict the corrosion ratio of the concrete cover. The determined analytical corrosion ratio agreed well with the test result. The effect factor analysis based on the finite element method indicated that increasing the concrete strength and concrete cover thickness delays concrete cracking and that the adjacent rebar causes the stress superposition phenomenon.

scholarly journals Applicability of existing crack controlling criteria for structures with large concrete cover thickness: Review.

2020 ◽  
Author(s):  
Chavin Naotunna ◽  
S.M Samindi M.K Samarakoon ◽  
Kjell Fosså
Keyword(s):  
Crack Width ◽  
Concrete Cover ◽  
Design Stage ◽  
Rc Structures ◽  
Model Code ◽  
Design Life ◽  
Service Load ◽  
Model Code 2010 ◽  
Cover Thickness ◽  
Calculation Models

Adverse effects from the cracks in Reinforced Concrete (RC) structures are controlled at the structural design stage. Cracks due to service load are controlled by limiting the ‘calculated crack width’ to a ‘maximum allowable crack width’. With the understanding of social and economic advantages of long design life structures, there is a trend of constructing structures up to 300 years of design life. To enhance durability, such structures require relatively large concrete cover thickness. The existing ‘crack width calculation models’, have to be validated before using on such large cover structures. The predictions of crack width calculation models in Eurocode 2, Model Code 2010, Japanese Code, American Code and British code were compared with the results of recent experiments with large cover specimens. It could identify that the aforementioned models have to be improved to predict the crack widths of large cover structures. The necessary improvements of each model have been identified. Next, a literature survey was conducted to check the applicability of the existing ‘allowable crack width limits’, for the structures with large concrete covers. To effectively use the existing allowable limits on such structures, the necessary improvements and future works have been identified considering the durability, aesthetic and tightness criteria.

scholarly journals Finite element analysis on the bond behavior of steel bar in salt–frost-damaged recycled coarse aggregate concrete

2021 ◽  
Vol 60 (1) ◽  
pp. 853-861
Author(s):  
Tian Su ◽  
Ting Wang ◽  
Haihe Yi ◽  
Rui Zheng ◽  
Yizhe Liu ◽  
...  
Keyword(s):  
Bond Strength ◽  
Concrete Cover ◽  
Bond Slip ◽  
Bond Behavior ◽  
Steel Bar ◽  
Calculation Results ◽  
Cover Thickness ◽  
Bar Diameter ◽  
Good Agreement ◽  
Ultimate Bond Strength

Abstract In this article, the ABAQUS finite element software is used to simulate the bond behavior of the steel bar in salt–frost-damaged recycled coarse aggregate concrete, and the influence of the steel bar diameter and the concrete cover thickness on the bond strength is investigated. The result shows that the calculated bond–slip curve is in good agreement with the experimental bond–slip curve; the mean value of the ratio of the calculation results of ultimate bond strength to the experiment results of ultimate bond strength is 1.035, the standard deviation is 0.0165, and the coefficient of variation is 0.0159, which proves that the calculation results of the ultimate bond strength are in good agreement with the experimental results; with the increase of steel bar diameter and the concrete cover thickness, the ultimate bonding strength of RAC and steel increases; the calculation formulas for the ultimate bond strength of specimens with different steel bar diameters (concrete cover thickness) after different salt–frost cycles are obtained.

scholarly journals Performance of Tension Lap-Splice in Lightweight Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 181-186
Keyword(s):  
Failure Modes ◽  
Lightweight Concrete ◽  
Cost Savings ◽  
Concrete Cover ◽  
Steel Reinforcement ◽  
Moment Capacity ◽  
Bond Behavior ◽  
Lap Splice ◽  
Cover Thickness ◽  
Bar Diameter

The use of Light-Weight Concrete (LWC) in modern construction has resulted in efficient designs and considerable cost savings by reducing structural own weight and supporting footings sections. The purpose of this paper is to investigate the Lap-Splice behavior between LWC and steel reinforcement (RFT). The tested specimens were divided into four groups to study the effect of main variables: steel reinforcement bar size, internal confinement (stirrups), splice length and concrete cover thickness. Four-point bending tests were carried out on test specimens to evaluate the performance of lap splices under pure bending. Bond behavior and failure modes were noted to be similar in the normal concrete and in the LWC. In tested beams, it was observed that the bar size has a significant influence on the mean bond stress in the splice. Improving radial tensile strength by using increasing stirrups number improves the bond behavior. The splice length up to 35 times bar diameter decreased the moment capacity of beam. The splice length of 55 times bar diameter results in the same capacity of the beam without any splice.

Anchorage/lap strength of bars in RC structures in case of low concrete cover thickness

2021 ◽  
Author(s):  
Fabrizio Palmisano ◽  
John Cairns ◽  
Antonia Menga
Keyword(s):  
Environmental Economic ◽  
Concrete Cover ◽  
Rc Structures ◽  
Existing Structures ◽  
Codes Of Practice ◽  
The World ◽  
Cover Thickness

<p>In recent years the assessment of existing structures has become a topic of huge interest all over the world due to environmental, economic and socio-political assets. However, the approach to the assessment of existing structures is in many aspects different from that used for the design of a new structure. This is why there is a necessity to develop new formulations for old materials and products that are consistent with the requirements and the reliability-based approach of current codes of practice. In this scenario, this article analyses a topic very common in existing RC structures, namely the effect of low concrete cover thickness on the anchorage/lap strength of bars. The main aim of the article is to give practical formulations that can be included in future codes of practice. To this aim a novel formulation recently proposed is firstly analysed and then validated against a database of tests taken from the literature.</p>

BOND AND FLEXURAL BEHAVIOR OF SELF-CONSOLIDATING CONCRETE BEAMS REINFORCED WITH GFRP BARS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Slamah Krem ◽  
Khaled Soudki
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Cover ◽  
Flexural Behavior ◽  
Self Consolidating Concrete ◽  
Gfrp Bars ◽  
Cover Concrete ◽  
Concrete Type ◽  
Cover Thickness ◽  
Frp Bars

Self-consolidating concrete (SCC) is widely used in the construction industry. SCC is a high-performance concrete with high workability and consistency allowing it to flow under its own weight without vibration. Despite the wide spread of SCC applications, bond behavior of FRP bars embedded in SCC beams has not been fully studied. This paper presents an experimental and analytical analysis of fifteen beams reinforced with glass fiber reinforced polymer (GFRP) bars. The test parameters were the concrete type, bar diameter, concrete cover thickness and embedment length. All beams were tested in four-point bending to failure. The average bond stresses of GFRP bars in SCC were found comparable to those in NVC. However, FRP bars embedded in SCC beams had higher bond stresses within uncracked region of the beams than those embedded in NVC beams. In contrast, GFRP bars in SCC had lower bond stresses than FRP bars in NVC within the cracked region. Results indicated that when cover concrete thickness dropped less than 2 db, the splitting bond failure is predominant.

Influence of Cracks on the Durability of RC Structures

2008 ◽  
Vol 385-387 ◽  
pp. 769-772
Author(s):  
Lucio Nobile
Keyword(s):  
Process Model ◽  
Load Capacity ◽  
Concrete Cover ◽  
Uniform Corrosion ◽  
Exposure Test ◽  
Bond Behaviour ◽  
Rc Structures ◽  
Pull Out ◽  
Flexural Member ◽  
Damage Process

To carry out maintenance and assessment of reinforced concrete (RC) structures, a good understanding of the effect of the change in bond behaviour of reinforcement during service life is essential. Steel reinforcement is subjected to corrosion due to carbonation and chloride attack. The former ordinarily induces uniform corrosion, the latter induces generally localised corrosion at cracks level. The existence of cracks and the crack width affect the starting points of corrosion, as indicated by the results of the exposure test carried out by Shiessl et al.[1]. Corresponding techniques, such as non-destructive in-situ testing for concrete cover thickness, permeability and the positions of the reinforcing bars, are helpful to model the real behaviour. Cracked portion around the tensile reinforcement in a flexural member can be considered to be equivalent to a concrete member having a single reinforcement subjected to pull-out force at both ends. In this paper a damage process model is proposed based on slip crack propagation in order to evaluate the effective load capacity.

scholarly journals The level of effect of tightening of steel reinforcing a 16mm gauge when the reinforced concrete is exposed to fire with varying concrete cover distance: مدى تأثر قوى الشد لحديد تسليح قياس 16مم عند تعرض الخرسانة المسلحه به للنار مع أختلاف مسافة الغطاء الخرساني

2017 ◽  
Vol 1 (2) ◽  
Author(s):  
M. Dawood Salem Jasim Al - Kandari
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Tensile Test ◽  
Concrete Cover ◽  
Steel Bar ◽  
Two Samples ◽  
Bar Diameter

This research is to study how the fire affecting the tensile strength of two samples for reinforced concrete with different dimension of concrete covered the steel bar diameter was 16 mm. a two form made from wood and the 16mm steel bar embedded inside when the concrete poured then the form was opened after 7 days then the sample has been exposed to fire for 80 minutes then after it cooled up the steel bar had been taken to tensile test.        

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