scholarly journals Temporal analysis of the performance of an elevated concrete tank considering the corrosion of the steel reinforcement

2021 ◽  
Vol 15 (56) ◽  
pp. 94-114
Author(s):  
Hocine Hammoum ◽  
Nassima Miloudi ◽  
Karima Bouzelha ◽  
Younes Aoues ◽  
Ouali Amiri
Keyword(s):  
Reinforced Concrete ◽  
Pitting Corrosion ◽  
Temporal Analysis ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Atmospheric Conditions ◽  
Engineering Structures ◽  
Corrosion Risk ◽  
Concrete Tank ◽  
Loss Of Strength

Reinforced concrete water storage tanks are civil engineering structures subject to very aggressive atmospheric conditions that expose them to harmful corrosion risk. This dangerous phenomenon caused by the penetration of chloride ions causes pitting corrosion and leads to the reduction of the section of the reinforcements and consequently to the loss of strength and the structure performance. In this study, we are interested in analyzing the performance of an elevated storage tank, taking into account the corrosion of the reinforcements subjected to tensile stress, by considering environments with different rates of aggressiveness. A method based on Housner's model is used to evaluate the tension stresses in the reinforced concrete (RC) pedestal (supporting system) of the tank, subjected to the seismic actions. A pitting corrosion model is developed in order to determine the evolution in time of the reinforcements section in different environments. Several parameters influencing corrosion are taken into account, such as concrete cover and the concentration of chlorides ions.

scholarly journals New warning sensors to detect corrosion risk in reinforced concrete

2019 ◽  
Vol 289 ◽  
pp. 06002
Author(s):  
Mahdi Khadra ◽  
Elisabeth Marie-Victoire ◽  
Myriam Bouichou ◽  
Christian Crémona ◽  
Stéphanie Vildaer
Keyword(s):  
Reinforced Concrete ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Cultural Value ◽  
Original Material ◽  
Reinforcing Bars ◽  
First Results ◽  
Corrosion Risk ◽  
Deterioration Mechanism ◽  
Different Depths

Corrosion is the most frequent but also the most deleterious deterioration mechanism affecting reinforced concrete. In addition to the economic impact of the repair works, for historical concrete structures, corrosion can generate irreversible losses of original material of great cultural value. If the usual non-destructive electrochemical methods have highlighted their efficiency in evaluating on-going corrosion activity, they also have pointed out their drawbacks for accurate extrapolation and prevention. To prevent the corrosion phenomenon, by detecting the penetration of aggressive agents, a new warning sensor system has been developed. The principle of the technique is to embed thin metallic sheets (called orphan blades) in the concrete cover, at different distances from the surface to the reinforcing bars. Then the corrosion of those very reactive orphan blades is followed during the propagation of the carbonation front and/or the penetration of chloride ions using stimulated infrared thermography. The corrosion of the sensors at different depths is indicative of the ingress speed of the front and can alert about the risk of corrosion of reinforcing bars in the concrete. The purpose of this study is to present this new technique and the first results obtained in the laboratory on corroded and non-corroded sensors.

Axial-Bending Interaction Diagrams of Reinforced Concrete Columns Exposed to Chloride Attack

2016 ◽  
Vol 847 ◽  
pp. 415-422
Author(s):  
Giuseppe Carlo Marano ◽  
Rita Greco
Keyword(s):  
Reinforced Concrete ◽  
Pitting Corrosion ◽  
Residual Strength ◽  
Concrete Columns ◽  
Concrete Cover ◽  
Structural Element ◽  
Reinforced Concrete Columns ◽  
Interaction Diagram ◽  
Capacity Degradation ◽  
Chloride Attack

This paper focuses on reinforced concrete columns load carrying capacity degradation over time due to chloride induced steel pitting corrosion. The structural element is exposed to marine environment and the effects of corrosion are described by the time degradation of the axial-bending interaction diagram. Because chlorides ingress and consequent pitting corrosion propagation are both time-dependent mechanisms, the study adopts a time-variant predictive approach to evaluate residual strength of corroded reinforced concrete columns at different lifetimes. Corrosion initiation and propagation process is modelled by taking into account all the parameters, such as external environmental conditions, concrete mix proportion, concrete cover and so on, which influence the time evolution of the corrosion phenomenon and its effects on the residual strength of RC columns.

scholarly journals Numerical analysis of reinforced concrete beam subject to pitting corrosion

2022 ◽  
Vol 22 (1) ◽  
pp. 201-222
Author(s):  
Éverton Souza Ramos ◽  
Rogério Carrazedo
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Pitting Corrosion ◽  
Numerical Study ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Structural Element ◽  
Deterministic Models ◽  
Faraday’S Law ◽  
Parametric Analyses

Abstract This paper presents a numerical study about the effects of chloride-induced corrosion on the service life of structures. A two-dimensional geometrically nonlinear mechanical model based on Finite Element Method (FEM) was developed for reinforced concrete structures. The corrosion initiation stage was evaluated by Fick's diffusion laws. The corrosion propagation was carried out by deterministic models based on Faraday's law. Pitting corrosion was simulated in the reinforcements by pit elements, distributed longitudinally on the steel rebars, which degrade the physical properties over time. The service life was determined by the crack width.Two parametric analyses were performed. In the first analysis, five models were created with a variablecover thickness and water/cement ratio (w/c). In the second analysis, the reduction in yield stress due to corrosion was considered.The results showed that the concrete cover thicknessand the w/c ratio significantly influence the service life. The reduction of the cover thickness from 30 mm to 25 mm resulted in 21.26% reduction in service life, whilethe increase in the w/c ratio from 0.50 to 0.55 caused 32.98% reduction in service life of the structural element analyzed.

APPLICATION OF INNOVATIVE MATERIALS IN PRECAST CONCRETE STRUCTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Klaus Holschemacher
Keyword(s):  
Reinforced Concrete ◽  
Construction Industry ◽  
Precast Concrete ◽  
Cementitious Materials ◽  
Concrete Cover ◽  
Fiber Reinforced Concrete ◽  
Textile Reinforced Concrete ◽  
Construction Methods ◽  
Corrosion Risk ◽  
Innovative Materials

Construction industry contributes essentially to Germany’s gross domestic product (GDP). In 2015 construction investments amounted around 300 billion Euro corresponding to a share of 10% of total GDP. Because of the essential importance of construction industry there are many activities aiming on reduction of construction costs and improvement of durability and sustainability. Recent tendencies in precast concrete industry include application of innovative materials like self-compacting concrete, fiber reinforced concrete, textile reinforced concrete, carbon concrete composite and strain hardening cementitious materials. The report describes the material developments and first applications for precast concrete members. By the application of non-metallic reinforcement, such as carbon meshes and carbon bars, there is no corrosion risk for the reinforcement resulting in an essentially lower concrete cover and depth of structural members. However, the use of carbon reinforcement requires new design concepts and new construction methods. By solving these problems there is a big chance for precast concrete industry to enhance their market share.

scholarly journals Diagnostics of Concrete and Steel in Elements of an Historic Reinforced Concrete Structure

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 306
Author(s):  
Paweł Tworzewski ◽  
Wioletta Raczkiewicz ◽  
Przemysław Czapik ◽  
Justyna Tworzewska
Keyword(s):  
Reinforced Concrete ◽  
Detection System ◽  
Thickness Distribution ◽  
Pulse Method ◽  
Test Methods ◽  
Concrete Cover ◽  
Reinforced Concrete Structure ◽  
Corrosion Risk ◽  
Cover Thickness ◽  
Non Destructive

Existing buildings, especially historical buildings, require periodic or situational diagnostic tests. If a building is in use, advanced non-destructive or semi-destructive methods should be used. In the diagnosis of reinforced concrete structures, tests allowing to assess the condition of the reinforcement and concrete cover are particularly important. The article presents non-destructive and semi-destructive research methods that are used for such tests, as well as the results of tests performed for selected elements of a historic water tower structure. The assessment of the corrosion risk of the reinforcement was carried out with the use of a semi-destructive galvanostatic pulse method. The protective properties of the concrete cover were checked by the carbonation test and the phase analysis of the concrete. X-ray diffractometry and thermal analysis methods were used for this. In order to determine the position of the reinforcement and to estimate the concrete cover thickness distribution, a ferromagnetic detection system was used. The comprehensive application of several test methods allowed mutual verification of the results and the drawing of reliable conclusions. The results indicated a very poor state of the reinforcement, loss in the depth of cover and sulphate corrosion.

Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton

2020 ◽  
Vol 24 (1) ◽  
pp. 11-16
Author(s):  
Saddam - Husein ◽  
Rudy Djamaluddin ◽  
Rita Irmawaty ◽  
Kusnadi Kusnadi
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Steel Reinforcement ◽  
Fiber Reinforced Polymer ◽  
Mode Analysis ◽  
Flexural Capacity ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Gfrp Bar

SADDAM HUSEIN. Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton (dibimbing oleh Rudi Djamaluddin dan Rita Irmawaty) Struktur beton bertulang yang menggunakan tulangan baja pada daerah korosif, menjadi rawan terhadap kerusakan atau penurunan kekuatannya akibat korosi.Korosi pada tulangan baja merupakan salah satu faktor penyebab menurunnya kekuatan struktur beton bertulang. Salah satu material yang dikembangkan mengatasi korosi adalah penggunaan material tulangan GFRP (Glass Fiber Reinforced Polymer). Penelitian ini bertujuan untuk menganalisa kapasitas lentur dan pola kegagalan balok beton tanpa selimut dengan menggunakan material tulangan GFRP bar.   Desain penelitian merupakan eksperimental laboratorium dengan rekapitulasi sebanyak 6 sampel yang terdiri dari 2 Balok beton menggunakan tulangan baja dengan selimut beton, 2 balok beton menggunakan tulangan GFRP bar dengan selimut beton, 2 balok beton menggunakan GFRP bar tanpa selimut beton. Metode pengujian dilakukan dengan dengan pengujian lentur statik monotonik dan Analisis data menggunakan uji kondisi retak awal dan kondisi ultimit.   Hasil penelitian ini menunjukkan bahwa kapasitas lentur pada balok dengan tulangan GFRP bar lebih besar dibandingkan dengan balok tulangan baja dan mampu meningkatkan kapasitas lentur balok dalam menahan beban sebesar 39.76 %, pola kegagalan beton yang terjadi pada balok tulangan baja mengalami kegagalan lentur tekan ditandai dengan retakan yang terjadi pada sisi tertekan dan membentuk retakan tegak dengan sumbu netral beton yang tertekan, sedangkan pada balok beton tulangan GFRP tanpa selimut mengalami kegagalan keruntuhan tekan geser dengan kondisi tulangan berdeformasi (bi-linear) dengan retak miring dan secara tiba-tiba menjalar menuju sumbu netral beton yang tertekan sehingga terjadilah keruntuhan secara tiba-tiba.     SADDAM HUSEIN.Failure mode analysis of concrete Beams Using GFRP rebar Without concrete cover (supervised by Rudi Djamaluddin and Rita Irmawaty)   Reinforced concrete that uses rebar steel in corrosive areas, are prone to damage or decreased strength due to corrosion. Corrosion in the steel reinforcement is one of the factors that decreasing strength of reinforced concrete. One of the materials developed to overcome corrosion is the use of GFRP (Glass Fiber Reinforced Polymer) reinforcement material. This study aims to analyze the flexural capacity and failure mode of concrete beams without concrete cover using material GFRP bar as reinforcement.   The research design was an experimental laboratory with a recapitulation of 6 samples consisting of 2 beams using steel reinforcement with concrete cover.2 concrete beams using reinforcement GFRP bar with concrete cover, 2 beams using GFRP bars without concrete cover. The  research method uses the monotonic static flexure and analyzing the data using the initial crack condition and ultimate conditions test.   The results of the research indicate the flexural capacity of the beams with GFRP bar reinforcement is higher than steel reinforcement beams and can increase 39.76% of the flexural capacity of the beams in holding loads , the failure mode analysis occurs in steel reinforcing beam experiences compressive failure. Failure was characterized  by cracks that occur on the depressing side and form an upright crack with the neutral axis of the compressed concrete, whereas in GFRP reinforced concrete beams without concrete cover, failure of shear compression with conditions of deformed reinforcement (bi-linear) with sloping cracks and suddenly spread towards the neutral axis of the compressed concrete so that there was a sudden collapse.

scholarly journals Time-Dependent Reliability Analysis of Reinforced Concrete Beams Subjected to Uniform and Pitting Corrosion and Brittle Fracture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1820
Author(s):  
Mohamed El Amine Ben Seghier ◽  
Behrooz Keshtegar ◽  
Hussam Mahmoud
Keyword(s):  
Reinforced Concrete ◽  
Brittle Fracture ◽  
Reliability Analysis ◽  
Pitting Corrosion ◽  
Structural Reliability ◽  
Time Dependent ◽  
State Function ◽  
Rc Beams ◽  
Highly Nonlinear ◽  
Reliability Method

Reinforced concrete (RC) beams are basic elements used in the construction of various structures and infrastructural systems. When exposed to harsh environmental conditions, the integrity of RC beams could be compromised as a result of various deterioration mechanisms. One of the most common deterioration mechanisms is the formation of different types of corrosion in the steel reinforcements of the beams, which could impact the overall reliability of the beam. Existing classical reliability analysis methods have shown unstable results when used for the assessment of highly nonlinear problems, such as corroded RC beams. To that end, the main purpose of this paper is to explore the use of a structural reliability method for the multi-state assessment of corroded RC beams. To do so, an improved reliability method, namely the three-term conjugate map (TCM) based on the first order reliability method (FORM), is used. The application of the TCM method to identify the multi-state failure of RC beams is validated against various well-known structural reliability-based FORM formulations. The limit state function (LSF) for corroded RC beams is formulated in accordance with two corrosion types, namely uniform and pitting corrosion, and with consideration of brittle fracture due to the pit-to-crack transition probability. The time-dependent reliability analyses conducted in this study are also used to assess the influence of various parameters on the resulting failure probability of the corroded beams. The results show that the nominal bar diameter, corrosion initiation rate, and the external loads have an important influence on the safety of these structures. In addition, the proposed method is shown to outperform other reliability-based FORM formulations in predicting the level of reliability in RC beams.

scholarly journals Influence of Patching on the Shear Failure of Reinforced Concrete Beam without Stirrup

2021 ◽  
Vol 6 (7) ◽  
pp. 97
Author(s):  
Stefanus Adi Kristiawan ◽  
Halwan Alfisa Saifullah ◽  
Agus Supriyadi
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Numerical Study ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Shear Capacity ◽  
Rc Beam ◽  
Shear Span ◽  
Shear Cracking

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

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