scholarly journals Probabilistic corrosion time initiation modelling in reinforced concrete structures using the BEM

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Giovanni Pais Pellizzer ◽  
Edson Denner Leonel
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Analytical Models ◽  
Mechanical Degradation ◽  
Reinforced Concrete Structures ◽  
Structural Durability ◽  
Probabilistic Values ◽  
Propagation Period ◽  
Corrosion Time

Abstract The reinforcement’s depassivation in reinforced concrete structures occurs when the chloride concentration at the reinforcement’s interface reaches the threshold content. The depassivation phenomenon starts the propagation period, in which huge mechanical degradation processes are triggered. Moreover, it is well established that the propagation period is considerably shorter than the initiation period. Therefore, the accurate prediction of the corrosion time initiation is a major issue in structural durability domain. This study presents a transient formulation based on the Boundary Element Method (BEM) for the corrosion time initiation assessment. The diffusion fields evaluated by the BEM are utilized into a probabilistic framework, which enables the assessment of probabilistic values for corrosion time initiation. Therefore, the formulation handles properly the uncertainties in this problem, which is largely subjected to randomness. Three applications are presented. The robustness and accuracy of the proposed approach over classical analytical models are highlighted.

scholarly journals COMBINED EFFECT OF CARBONATION AND CHLORIDE AGGRESSION: DEG-RADATION OF REINFORCED CONCRETE STRUCTURES

2018 ◽  
Author(s):  
L.V. KIM ◽  
E.E. SHALYI ◽  
S.N. LEONOVICH ◽  
N.A. BUDREVICH
Keyword(s):  
Reinforced Concrete ◽  
Ph Value ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Protective Layer ◽  
Sharp Decrease ◽  
Threshold Concentration ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structures ◽  
Cross Sectional

Corrosion reinforcement marine hydraulic structures due to chloride aggression and carbonization of concrete leads to a sharp decrease in the safety of the structure. The steel reinforcement will be subjected to a so-called depassivation process, once the chloride concentration on surface exceeds a certain threshold concentration, or the pH value in the protective layer of concrete decreases to a threshold value due to carbonation. Electrochemical reactions begin to occur with the formation of corrosion products with the penetration of oxygen on the steel reinforcement surface. This leads to cracking of the protective layer of concrete. It should also be taken into account that, due to corrosion mechanisms, the cross-sectional area of the reinforcement also decreases. The article suggests a method for predicting the complex degradation of reinforced concrete structures, taking into account various mechanisms of corrosion wear, which will allow developing effective ways to improve the durability and maintainability of structures operated in the marine environment.

Nonliear Analysis of Reinforced Concrete Structures Considering Plastic Deformation

2015 ◽  
Vol 802 ◽  
pp. 231-236
Author(s):  
Mirzakhid Khamitovich Miralimov
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Computational Method ◽  
Analytical Models ◽  
Reinforced Concrete Structures ◽  
Strain Diagram ◽  
Stress Strain ◽  
Plastic Properties ◽  
Nonlinear Properties ◽  
Limiting Condition

Analytical models and the basic preconditions for analysis of concrete and reinforced concrete structures should be established based on actual plastic properties of concrete and reinforcement, as well as consideration of presence of cracks in the concrete. It is known that the relationship between stress and strain in reinforced concrete is significantly different in the stage of work with cracks and without them. Development of computational method opens wide prospects in this direction. In this work the calculation of strength and definition of forces in constructive elements of structure from operational loadings are made on the basis of the finite element method. Analysis is carried out with the use of quadrangular isoparametric and beam elements by the method of level-by-level plasticization. Analytical model contains the nonlinear properties of concrete and reinforcement. Method and algorithm of calculation have been developed taking into account of real stress-strain diagrams from experiment. Method and algorithm of calculation of reinforced concrete designs include the limiting condition of deformation on the basis of known stress-strain diagram both for reinforcement and concrete. An example of analysis involving a tunnel structure for an underground station to determine internal forces using the proposed method was shown.

Nonlinear Vibration Characteristics of Fatigue Damaged Reinforced Concrete Structures

2005 ◽  
Vol 297-300 ◽  
pp. 2592-2597
Author(s):  
Jin Ho Kim
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Concrete Structures ◽  
Analytical Models ◽  
Fatigue Properties ◽  
Reinforced Concrete Structures ◽  
Isolation System ◽  
Discrete Crack ◽  
Isolation Systems

In this paper, nonlinear vibration techniques were applied to investigate stages of progressive damage in three vibration isolation systems induced by dynamic loadings. Analytical models for reinforced concrete structures of three isolation systems were developed based on FEM with discrete crack concept. Vibration response spectra and the spectra of forces transmitted through the isolators were computed with respect to stationary dynamic loads. In addition, fatigue properties of concrete structures were examined for given materials’ properties and given geometries. The results indicated that the proposed isolation system 3 can improve fatigue resistance by extending fatigue life and changing the failure mode from shear to flexure.

scholarly journals Temperature action in analysis of thermal stressed state of massive concrete and reinforced concrete structures

2018 ◽  
Vol 245 ◽  
pp. 03016 ◽  
Author(s):  
Aleksandra Makeeva ◽  
Aleksandra Amelina ◽  
Kirill Semenov ◽  
Yuriy Barabanshchikov
Keyword(s):  
Reinforced Concrete ◽  
Stressed State ◽  
Diurnal Temperature Range ◽  
Thermal Stresses ◽  
Concrete Structures ◽  
Analytical Models ◽  
Reinforced Concrete Structures ◽  
Construction Period ◽  
Massive Concrete ◽  
Temperature Action

The work is dedicated to research of the thermal stresses state of massive concrete and reinforced concrete structures in construction period. The article examines the results of the analysis of the thermal stress state, which occurs in massive concrete ground slab with thickness of 1 m. The study was conducted with using analytical models, which include the factor of diurnal temperature range in comparison with simplified methods. Authors established that solving the problem of thermal stressed state of the massive foundation slabs in the building period without taking into account the influence temperature changing during the month might not cause to significant deviation of the real diagram of the thermal stresses and elongation deformations in the structures body: error is less than 0.5%.

Effect of Cathodic Protection Systems with Zn-Mesh Sacrificial Anodes on Reinforced Concrete Structures in an Accelerated Marine Environment

2013 ◽  
Vol 800 ◽  
pp. 365-374 ◽  
Author(s):  
Jin A Jeong ◽  
Chung Kuk Jin
Keyword(s):  
Reinforced Concrete ◽  
Current Density ◽  
Cathodic Protection ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Reinforced Concrete Structures ◽  
Marine Environments ◽  
Concrete Piles ◽  
Sacrificial Anodes ◽  
Protection Potential

In the present study, corrosion and cathodic protection (CP) characteristics of concrete piles exposed to marine environments such as marine bridge columns or pier structures were evaluated under simulated conditions. The accelerated environmental tests were carried out at an elevated temperature (40°C) and a high chloride concentration (15%). The protection potential of CP systems with Zn-mesh sacrificial anodes applied to piles was inversely proportional to the water content in the concrete. When the CP system was applied after corrosion initiation and propagation (CProt), the protection current density was higher than when the CP system was applied at the beginning of structural construction (CPrev). However, the four-hour depolarization potential was higher in the latter case than in the former. In addition, it was found that even though the current density of the CPrev system was relatively lower than that of the CProt system, the CPrev system was also able to prevent corrosion. Consequently, both CProt and CPrev systems are very effective at preserving reinforced concrete structures, especially in marine environments.

scholarly journals Reliability algorithms applied to reinforced concrete structures durability assessment

2012 ◽  
Vol 5 (4) ◽  
pp. 440-450 ◽  
Author(s):  
C. G. Nogueira ◽  
E. D. Leonel ◽  
H. B. Coda
Keyword(s):  
Reinforced Concrete ◽  
Diffusion Process ◽  
Concrete Structures ◽  
Threshold Level ◽  
Concrete Cover ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Reinforced Concrete Structures ◽  
Reliability Method ◽  
Corrosion Time

This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to ions chloride penetration. Structural durability is an important criterion which must be evaluated in every type of structure, especially when these structures are constructed in aggressive atmospheres. Considering reinforced concrete members, chloride diffusion process is widely used to evaluate the durability. Therefore, at modelling this phenomenon, corrosion of reinforcements can be better estimated and prevented. These processes begin when a threshold level of chlorides concentration is reached at the steel bars of reinforcements. Despite the robustness of several models proposed in the literature, deterministic approaches fail to predict accurately the corrosion time initiation due to the inherently randomness observed in this process. In this regard, the durability can be more realistically represented using probabilistic approaches. A probabilistic analysis of ions chloride penetration is presented in this paper. The ions chloride penetration is simulated using the Fick's second law of diffusion. This law represents the chloride diffusion process, considering time dependent effects. The probability of failure is calculated using Monte Carlo simulation and the First Order Reliability Method (FORM) with a direct coupling approach. Some examples are considered in order to study these phenomena and a simplified method is proposed to determine optimal values for concrete cover.

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