Experimental investigation of the relationships between residual cross-section shapes and the ductility of corroded bars

Zhu, Wenjun; François, Raoul

doi:10.1016/j.conbuildmat.2014.07.059

Cited by 59 publications

(24 citation statements)

References 18 publications

(19 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This means that for losses of transversal section over 20% there is a trend of a progressive decrease of strengths (yield and ultimate) of the corroded reinforcement. In this sense, the damage made by pits to the transversal section of the corroded reinforcement promotes variations in the position of the axis of the bars along their length, generating eccentricities between the axis position of successive sections of the bars, producing gradients of efforts between those sections when submitted to tension, as also found in Zhu and François [19]. Thus, the effects of corrosion by pits may manifest not only by the loss of the transversal section of protruding reinforcing steel, but also in the geometric change of the axis of their transversal sections, contributing for an irregular behavior and making difficult the framing of a decreasing trend of those mechanical properties for values of section loss under 20%.…”

Section: Figure 13mentioning

confidence: 80%

“…Generally, independently if the corrosion method of bars is accelerated in laboratory or under natural conditions, the mentioned studies point for a decrease in values regarding yield strength, ultimate strength, final stretching and ductility, as the loss of mass of the corroded rebar increases. The influence of the transversal section over the mechanical properties of the reinforcing steel is presented in studies from Apostolopoulos [18] and Zhu and François [19]. In the first study, bars were corroded in a salt fog chamber until 120 days.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of corrosion degree on mechanical properties of reinforcements buried for 60 years

Balestra

Lima

Mendes

et al. 2018

Rev. IBRACON Estrut. Mater.

View full text Add to dashboard Cite

ResumoThis paper studies the influence of the corrosion degree calculated by the mass loss and by the smaller diameters on the yield strength, ultimate strength and final elongation. Reinforcements buried and naturally corroded for 60 years were studied. The mechanical properties of the protruding reinforcing steel were compared to reference bars, which also remained buried for 60 years, but without going through the corrosion process. Micrographs, besides the chemical composition and the characterization of the aggressiveness of the soil were realized. The micrographs and the chemical composition show the presence of pits in the reinforcements and sulfur contents for steel above the prescriptions of the time when the foundations were initially implement, respectively. The results also show that the effects of pitting corrosion on the mechanical properties of the naturally corroded bars may not be adequately expressed by the mass loss. This type of corrosion (pits) produces geometric variations in the cross sections along the length of the test specimens, generating stress gradients between successive sections. This has a noticeable impact on the mechanical properties of the reinforcements. In general, the effects of corrosion are more pronounced on the ductility of the reinforcement. Regarding the aggressiveness of the soil, high corrosion rates were identified in the reinforcement, even with the soil being classified as essentially non-corrosive.Keywords: reinforcement corrosion, durability, mass loss, smallest diameter, corrosion degree, mechanical properties.Este artigo estuda a influência do grau de corrosão, calculado pela perda de massa e pelos menores diâmetros, sobre a resistência ao escoamento, limite de resistência e alongamento final em armaduras corroídas naturalmente. Essas armaduras permaneceram enterradas por 60 anos. As propriedades mecânicas das armaduras de espera foram comparadas às de barras de referência, que também permaneceram enterradas por 60 anos, mas sem sofrer o processo de corrosão. Foram realizadas micrografias, além da determinação da composição química e da caracterização da agressividade do solo onde as armaduras estavam enterradas. As micrografias e a composição química mostram a presença de pites nas armaduras e teores de enxofre acima das prescrições recomendadas para o aço na época de execução das fundações, respectivamente. Os resultados também mostram que os efeitos da corrosão por pites sobre as propriedades mecânicas das barras corroídas naturalmente podem não ser adequadamente expressos pela perda de massa. Esse tipo de corrosão (pites) produz variações geométricas nas seções transversais ao longo do comprimento dos corpos de prova, gerando gradientes de esforços entre seções sucessivas, que impactam de forma notória sobre suas propriedades mecânicas. De uma maneira geral, os efeitos da corrosão são mais pronunciáveis sobre a ductilidade das barras. Com relação à agressividade do solo, altas velocidades de corrosão foram identificadas nas armaduras, mesmo com o...

show abstract

Section: Figure 13mentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Effect of corrosion degree on mechanical properties of reinforcements buried for 60 years

Balestra

Lima

Mendes

et al. 2018

Rev. IBRACON Estrut. Mater.

View full text Add to dashboard Cite

show abstract

“…However, the experimental results were limited to only several beams in the investigation of this programme. In order to make clear the corrosion influence on the load-carrying capacity of the corroded beam and the relationships with the variability of the predicted values, the experimental results of B2Cl3 were compared with the results from the previous relevant studies, including the corroded beams B1Cl1 (Castel et al, 2000a(Castel et al, , 2000b, B2Cl1 (Zhang et al, 2009) and B2Cl2 (Zhu & Franc ois, 2014a, 2014b, 2014c in the same programme and some other programmes corroded by impressed current (El Maaddawy, Soudki, & Topper, 2005;Malumbela et al, 2010;Torres-Acosta et al, 2007).…”

Section: Comparison With Results Of the Other Programmesmentioning

confidence: 99%

Prediction of the residual load-bearing capacity of naturally corroded beams using the variability of tension behaviour of corroded steel bars

Zhu

François

2015

Structure and Infrastructure Engineering

Self Cite

View full text Add to dashboard Cite

This paper shows the residual behaviour of a highly corroded beam stored under sustained load in a chloride environment for 28 years. A non-corroded beam of the same age was also kept under sustained loading but in a non-aggressive environment as a control beam. Both beams were subjected to a three-point bending experiment until failure. The lower tensile reinforcement was extracted so that the tension properties of the corroded bars could be investigated. The yield strength, ultimate strength and ultimate strain of the corroded bars followed a normal distribution. Both the average value and the characteristic value of the yield strength, ultimate strength and ultimate strain were used to predict the residual mechanical performance of the beams. The changes in yield capacity and ultimate capacity of the corroded beam in comparison with the non-corroded beam are discussed in relation to the damage to the steel reinforcing bars. According to the variability of the residual behaviour of steel bars in tension experiment, it is possible to predict the variability in the load-bearing capacity of the corroded beams which fail due to the rupture of the tension bars.

show abstract

“…So stellen Ou et al unter Verwendung des Nennquerschnittszur Festigkeitsberechnung verständlicherweise fest, dass mit zunehmendem Korrosionsgrad eine abnehmende Zugfestigkeit einhergeht. Betrachtet man aber die Ergebnisse von Almusallam oder Zhu et al , zeigt sich, dass der Korrosionsgrad bei Berücksichtigung des kleinsten Restquerschnittseiner Probe im Allgemeinen nur einen relativ geringen Einfluss auf die effektive Zugfestigkeit hat. Eine tendenzielle Abnahme der Zugfestigkeit besteht hierbei nicht, da grundsätzlich sinkende Maximalzugkräfte mit abnehmenden Restquerschnitten und nicht mit den unveränderten Nennquerschnitten in Verbindung gebracht werden.…”

Section: Bisheriger Forschungsstandunclassified

“…Eine tendenzielle Abnahme der Zugfestigkeit besteht hierbei nicht, da grundsätzlich sinkende Maximalzugkräfte mit abnehmenden Restquerschnitten und nicht mit den unveränderten Nennquerschnitten in Verbindung gebracht werden. Zhu et al stellen dabei sogar eine leichte Zunahme der Zugfestigkeiten bei natürlich korrodierten Betonstahlproben fest. Doch ist auch erkennbar, dass die aus den Restquerschnitten ermittelten Zugfestigkeiten mit zunehmender Korrosion stärkeren Streuungen unterliegen.…”

Section: Bisheriger Forschungsstandunclassified

Veränderung der mechanischen Kenngrößen von Betonstabstählen durch chloridinduzierte Korrosion

Baumgärtner

Fraundorfer

Dauberschmidt

et al. 2019

Beton und Stahlbetonbau

View full text Add to dashboard Cite

Die Dauerhaftigkeit chloridexponierter Stahlbetonbauteile wird maßgeblich durch das Korrosionsverhalten des Bewehrungsstahls bestimmt. Hat ein Eintrag von Chloriden in kritischer Konzentration in das Bauteil stattgefunden, kann eine Lochfraßkorrosion initiiert werden. Die durch die Korrosion auftretenden, sehr lokalen Materialabträge können in kurzer Zeit zu hohen Querschnittsverlusten der Bewehrung führen. Für die Instandsetzungsplanung steht der/die Sachkundige PlanerIn vor der Aufgabe, Art und Umfang der Instandsetzungsmaßnahme festzulegen. Dabei stellt sich auch die Herausforderung, vorhandene Querschnittsverluste zielsicher beurteilen zu können. Eine exakte Bestimmung des Querschnittsverlusts auf der Baustelle ist jedoch aufgrund der Narbengeometrie nur schwer möglich, weshalb Querschnittsverluste häufig visuell abgeschätzt werden. Auch stellt sich die Frage, ob durch Lochfraßnarben Kerbspannungen verursacht werden, die einen Einfluss auf die Zugtragfähigkeit haben und zu abweichenden Festigkeitswerten im Vergleich zur reinen Querschnittsbetrachtung führen. Weiterhin zu hinterfragen ist der Einfluss der lokalen Schädigung auf das Dehnungsverhalten des Bewehrungsstahls und damit auf eine duktile Versagensankündigung des Bauteils. Zur besseren Beurteilbarkeit lochfraßgeschädigter Bewehrung wurden an der Hochschule München Versuche an Betonstählen mit einem weiten Schädigungsspektrum infolge chloridinduzierter Korrosion durchgeführt. Hierzu wurden natürlich geschädigte Betonstabstähle verschiedenen Durchmessers aus einer Tiefgarage der 1960er Jahre entnommen und im Labor künstlich geschädigte Proben hergestellt. Die Stahlproben wurden auf ihr optisches Erscheinungsbild, den Restquerschnitt sowie das Dehnungsverhalten und die statische Restzugtragfähigkeit hin untersucht.

show abstract

Experimental investigation of the relationships between residual cross-section shapes and the ductility of corroded bars

Cited by 59 publications

References 18 publications

Effect of corrosion degree on mechanical properties of reinforcements buried for 60 years

Effect of corrosion degree on mechanical properties of reinforcements buried for 60 years

Prediction of the residual load-bearing capacity of naturally corroded beams using the variability of tension behaviour of corroded steel bars

Veränderung der mechanischen Kenngrößen von Betonstabstählen durch chloridinduzierte Korrosion

Contact Info

Product

Resources

About