scholarly journals How Reliable is the Durability of RC Structures?

10.14311/634 ◽  
2004 ◽  
Vol 44 (5-6) ◽  
Author(s):  
B. Teplý ◽  
P. Rovnaník ◽  
Z. Keršner ◽  
P. Rovnaníková
Keyword(s):  
Service Life ◽  
Reliability Index ◽  
Statistical Evaluation ◽  
Limit State ◽  
Latin Hypercube Sampling ◽  
Simulation Method ◽  
Concrete Cover ◽  
Life Assessment ◽  
Rc Structures ◽  
Limiting Condition

The goal of this paper is to show some trends and time profiles of the reliability index relevant to the Serviceability Limit State considering the design service life of RC structures. The interactive web page “RC_LifeTime” – originated by the authors – is used (see http://www.stm.fce.vutbr.cz/). The depassivation of reinforcing steel due to carbonation is considered conservatively as a limiting condition. It is based on model concrete carbonation with 12 random input variables; the Latin Hypercube Sampling simulation method is used. RC_LifeTime offers the following options: Service Life Assessment – a statistical evaluation of service life, where optionally the target value of reliability index ß may be an additional input value and then the corresponding service life is the output value; Concrete Cover Assessment – a statistical evaluation of concrete cover value for the target service life, where optionally the required concrete cover value may be input in this case and the relevant reliability index ß describes the reliability of reinforcement depassivation. 

scholarly journals Modelling of Corrosion-Induced Concrete Cover Cracking Due to Chloride Attacking

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1440
Author(s):  
Pei-Yuan Lun ◽  
Xiao-Gang Zhang ◽  
Ce Jiang ◽  
Yi-Fei Ma ◽  
Lei Fu
Keyword(s):  
Service Life ◽  
Corrosion Current ◽  
Practical Experience ◽  
Concrete Cover ◽  
Premature Failure ◽  
Rc Structures ◽  
Structural Capacity ◽  
Cover Cracking ◽  
Deterioration Process ◽  
Cracking Process

The premature failure of reinforced concrete (RC) structures is significantly affected by chloride-induced corrosion of reinforcing steel. Although researchers have achieved many outstanding results in the structural capacity of RC structures in the past few decades, the topic of service life has gradually attracted researchers’ attention. In this work, based on the stress intensity, two models are developed to predict the threshold expansive pressure, corrosion rate and cover cracking time of the corrosion-induced cracking process for RC structures. Specifically, in the proposed models, both the influence of initial defects and modified corrosion current density are taken into account. The results given by these models are in a good agreement with practical experience and laboratory studies, and the influence of each parameter on cover cracking is analyzed. In addition, considering the uncertainty existing in the deterioration process of RC structures, a methodology based on the third-moment method in regard to the stochastic process is proposed, which is able to evaluate the cracking risk of RC structures quantitatively and predict their service life. This method provides a good means to solve relevant problems and can prolong the service life of concrete infrastructures subjected to corrosion by applying timely inspection and repairs.

Corrosion effects on seismic capacity of reinforced concrete structures

2019 ◽  
Vol 37 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Antonio Bossio ◽  
Francesco Fabbrocino ◽  
Tullio Monetta ◽  
Gian Piero Lignola ◽  
Andrea Prota ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Seismic Behavior ◽  
Concrete Cover ◽  
Residual Service Life ◽  
Seismic Capacity ◽  
Rc Structures ◽  
Behavior Simulation ◽  
Cover Cracking ◽  
Rc Structure

AbstractRecently, corrosion prevention and monitoring of reinforced concrete (RC) structures became an important issue for seismic assessment of such kind of structures. Therefore, it is important to develop adequate models to represent material degradation into seismic behavior simulation of RC structures. Because of its effects, corrosion represents the most important form of degradation for materials and structures, both for wide diffusion and the amount of danger it presents. To understand the corrosion process is critical in order to design RC structures that are able to guarantee the required service life and in order to understand the residual service life and strength of an existing structure. The seismic behavior of a corroded framed RC structure is analyzed by means of push-over analyses, which allow understanding the development of the global behavior of the structure. Three different degrees of corrosion penetration were simulated, by means of the reduction of bars and stirrups’ diameters and concrete cover cracking and spalling, and three different configurations of corrosion, depending on the number of corroded frames and sides of the structural elements.

Numerical Simulation Method for Predicting Chloride Concentration Distributing around Reinforcement in Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 3138-3142
Author(s):  
Xian Li Wang ◽  
Guang Shu Ma ◽  
Chun Ling Qi
Keyword(s):  
Numerical Simulation ◽  
Service Life ◽  
Chloride Concentration ◽  
Mass Conservation ◽  
Simulation Method ◽  
Second Law ◽  
Exposed Surface ◽  
Rc Structures ◽  
Numerical Simulation Method ◽  
Section Shape

The reinforcement in concrete alters the pathway for chloride transporting and in turn causes the chloride concentration to accumulate faster near the reinforcement closest to the exposed surface. A mass conservation matrix equation under the non-stable diffusion based on the Fick’s second law was derived. Hereby, a numerical simulation method for predicting chloride concentration in concrete was established utilizing the compiled module based on FEA. The validity of the method was verified by the comparison with the analytical results. The proposed method has a wider applicability for predicting the service life of RC structures. And it can be applied flexibly to any complicated section shape of RC members with multi-boundary attacked by chloride and the reinforcement considered simultaneously.

Evaluation of Additional Protection Methods to Control Reinforcement Corrosion

2016 ◽  
Vol 711 ◽  
pp. 37-44 ◽  
Author(s):  
Fabio Bolzoni ◽  
Silvia Beretta ◽  
Andrea Brenna ◽  
Maria Vittoria Diamanti ◽  
Luciano Lazzari ◽  
...  
Keyword(s):  
Service Life ◽  
Limit State ◽  
Chloride Concentration ◽  
Concrete Cover ◽  
Reinforcement Corrosion ◽  
Simplified Approach ◽  
Model Code ◽  
Open Questions ◽  
Additional Protection ◽  
Prevention Methods

The prevention of reinforcement corrosion is primarily achieved by using high quality concrete, adequate concrete cover and suitable casting and curing. Additional prevention methods are adopted when severe environmental conditions occur on structures requiring very long service life. While existing standards, EN 206 or Eurocode 2, adopt prescriptive approach, performance based methods can improve the evaluation of the service life and enable the comparison of available design options. The reliability of the prediction is very important and even widely used models (e.g. fib Model Code) still have open questions. In this paper different additional protection are evaluated: corrosion inhibitors, stainless steel rebars, concrete coatings. A simplified approach is used, considering that the serviceability limit state, i.e. initiation of corrosion in chloride containing environments, can be modeled through the analytical solution of the 2nd Fick’s law of diffusion. The main factors influencing corrosion initiation (critical chlorides concentration, chlorides diffusion coefficient, surface chloride concentration, concrete cover) are represented by distribution of values and the probability distribution of service life is evaluated by Monte Carlo simulation.

scholarly journals Assessment of Durability of Concrete Structure Subject to Carbonation with Application of Safety Factor

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Seung-Woo Pack ◽  
Min Sun Jung ◽  
Jun Won Kang ◽  
Ki Yong Ann ◽  
Janghwan Kim
Keyword(s):  
Service Life ◽  
Safety Factor ◽  
Goodness Of Fit ◽  
Probability Distributions ◽  
Concrete Cover ◽  
Urban Environments ◽  
Safety Factors ◽  
Rc Structures ◽  
Goodness Of Fit Tests ◽  
Optimal Probability

A reliability-based method for identifying appropriate safety factors for use in predicting the service life (i.e., corrosion-free life) of concrete structures subject to carbonation is described in this paper. Reinforced concrete (RC) columns located in CO2-rich urban environments were investigated to estimate their service life. Carbonation depths and cover depths were measured for sound, cracked, and jointed concrete cover conditions. The measurements were used to calculate safety factors for columns subject to carbonation. Goodness-of-fit tests were used to obtain optimal probability distributions for carbonation depths and cover depths. A reliability index of 1.28, corresponding to a 10% probability of corrosion initiation, was taken as a threshold for determining the safety factor. The safety factor proposed in this paper can be used to estimate the service life of RC structures subject to carbonation. The sensitivity of the safety factor to the casting method and coefficient of variation of the cover depth were also evaluated.

scholarly journals Heuristic Operator for Reliability Assessment of Frame Structures

2021 ◽  
Author(s):  
Ali Kaveh ◽  
Seyed Rohollah Hoseini Vaez ◽  
Pedram Hosseini ◽  
Mohammad Ali Fathali
Keyword(s):  
Reliability Index ◽  
Limit State ◽  
Simulation Method ◽  
Frame Structures ◽  
State Function ◽  
Limit State Function ◽  
Cross Sectional ◽  
Story Drift ◽  
Steel Frame Structures ◽  
External Loads

In structural design of steel frames, in order to achieve proper safety, the effect of uncertainties in the design and loading parameters of the structure must be considered. This approach is obtained by defining a reliability index. In this study, the Modified Dolphin Monitoring (MDM) operator was used to evaluate the reliability index of three well-known steel frame structures based on the Hasofer-Lind method. The reliability index was evaluated using the EVPS and VPS algorithms and with considering the MDM operator on them. The constraint of the last story drift is considered as limit state function. The random variables consist of external loads, modulus of elasticity, moment of inertia and cross-sectional areas. According to the number of evaluations of the limit state function, the results show the efficiency of this method in comparison to the Monte Carlo simulation method. Also, the values of the most probable point (MPP) are examined.

Determining Criteria for Assessment of RC Structures Affected by Carbonation-Induced Corrosion

2020 ◽  
Vol 868 ◽  
pp. 3-9
Author(s):  
Jan Mlčoch ◽  
Miroslav Sýkora
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Sustainable Construction ◽  
Major Influence ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Design Service Life ◽  
Structural Surface

The construction industry is now facing expanding and extensive activities in the area of assessing and retrofitting buildings and bridges that aligns with the sustainable construction strategy. These activities recognise the importance of extending the life of existing construction works thereby delivering environmental, economic and socio-political benefits. Reinforced concrete structures and their reliability are currently receiving considerable attention as a significant part of these structures reaches the design service life. Degradation processes such as carbonation- and chloride-induced corrosion have a major influence on the reliability and serviceability of concrete structures. The submitted study is primarily focused on reinforced concrete structures whose main degradation factor is carbonation of the concrete cover. Examples of such structures are cooling towers or industrial chimneys. Structures in the power industry are usually designed for service life of 40 years. Carbonation-induced corrosion results in visible cracks and unacceptable spalling of concrete cover. The aim of the study is to improve predictions of carbonation-induced corrosion propagation and to critically compare the criteria for degradation level assessment used in practice. The probabilistic analysis is based on measurements of concrete cover and carbonation depths and continuous observations of signs of corrosion on structural surfaces. The example of an industrial chimney shows that the limit of a severe failure, which requires (possibly repeated) minor repairs, is exceeded after about 17 years. The critical failure limit (30% of structural surface with visible signs of corrosion) is reached after 50 years, which seems to be sufficient as it is after 10 years than the usual design service life.

An Indicator Response Surface Method for Simulation-Based Reliability Analysis

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
Tong Zou ◽  
Zissimos P. Mourelatos ◽  
Sankaran Mahadevan ◽  
Jian Tu
Keyword(s):  
Reliability Analysis ◽  
Response Surface ◽  
Structural Reliability ◽  
Least Squares Method ◽  
Limit State ◽  
Sampling Technique ◽  
Latin Hypercube Sampling ◽  
Simulation Method ◽  
Indicator Function ◽  
Highly Nonlinear

An accurate and efficient Monte Carlo simulation method is presented for limit-state-based reliability analysis at both component and system levels, using a response surface approximation of the failure indicator function. The cross-validated moving least squares method is used to construct the response surface of the indicator function, based on an optimum symmetric Latin hypercube sampling technique. The proposed method can handle problems with complicated limit state(s). Also, it can easily handle implicit, highly nonlinear limit-state functions, with variables of any statistical distributions and correlations. The method appears to be particularly efficient for multiple limit state and multiple design point problems. Three structural reliability examples are used to highlight its superior accuracy and efficiency over traditional reliability methods.

scholarly journals Probabilistic service life of RC structures under carbonation

2017 ◽  
Vol 69 (6) ◽  
pp. 280-291 ◽  
Author(s):  
Pedro Faustino ◽  
Ana Brás ◽  
Fábio Gonçalves ◽  
Ângela Nunes
Keyword(s):  
Service Life ◽  
Rc Structures

scholarly journals The thermal history and stress state of a fresh steam-pipeline influencing its remaining service life

2011 ◽  
Vol 15 (3) ◽  
pp. 691-704 ◽  
Author(s):  
Gordana Bakic ◽  
Vera Sijacki-Zeravcic ◽  
Milos Djukic ◽  
Stevan Maksimovic ◽  
Dusan Plesinac ◽  
...  
Keyword(s):  
Service Life ◽  
Elevated Temperatures ◽  
Operating Temperature ◽  
Life Assessment ◽  
Temperature History ◽  
Significant Variable ◽  
Remaining Life ◽  
Pipe Bend ◽  
Steam Pipeline ◽  
Remaining Life Assessment

The service life of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh- and re-heated steam, depend on the exhaustion rate of the material. Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service- and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a ?324?36 pipe bend element of a fresh steam-pipeline, made of steel class 1Cr0.3Mo0.25V, after 160 000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.

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