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Article
Publication date: 24 May 2013

Ch. Alk. Apostolopoulos and Vassilios Kappatos

The corrosion of reinforcing steel bars reduces significantly the life and durability of concrete structures. This critical concern causes great losses to the economy and…

Abstract

Purpose

The corrosion of reinforcing steel bars reduces significantly the life and durability of concrete structures. This critical concern causes great losses to the economy and industry. The purpose of this paper is to estimate the effects of corrosion on the tensile mechanical properties of embedded steel bars B500c in concrete.

Design/methodology/approach

The concept is based on the curve fitting modelling, as well the mathematical correlation of the tensile mechanical properties between corroded bare and corroded embedded steel bars. In order to achieve this, extensive experiments were carried out on both bare (Ø8, 10, 12, 16 and 18 mm) and embedded (Ø8 mm) steel bars B500c, which were subjected to artificially accelerated corrosive conditions in a chloride‐rich atmosphere for several exposure times.

Findings

The research results show that the estimation method is available and effective in simulating the tensile mechanical behaviour of corroded reinforcing steel bars B500c.

Originality/value

As far as is known, this is the first time that an advanced data processing technique has been employed to try to find the mathematical correlation of the existing corrosion damage on the residual tensile properties between bare and embedded steel bars. It is argued that these models can be developed in order to reduce the need for expensive experimental investigation in materials.

Details

International Journal of Structural Integrity, vol. 4 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 5 March 2010

Ch. Alk. Apostolopoulos and C.A. Rodopoulos

Seismic loading can induce significant deformations to steel reinforcement. The recent approach suggested by Eurocode 8 indicates that steel reinforcement shall sustain…

Abstract

Purpose

Seismic loading can induce significant deformations to steel reinforcement. The recent approach suggested by Eurocode 8 indicates that steel reinforcement shall sustain repeated loading well within its elastic region, excluding by definition seismic loading. This paper aims to examine the behaviour of S500s steel reinforcement at strain ranges representing strains corresponding to small/medium earthquakes while significant attention has been paid to cases where the reinforcement has been corroded as this is most representative to aged buildings. The work concludes that the complex behaviour of steel reinforcement under low cycle fatigue conditions can be successfully treated via the use of the viscous stress. The latter is found to be independent to corrosion exposure while it holds the merits of ductility exhaustion on which most degradation models are based.

Design/methodology/approach

This paper establishes a relationship between the cumulative effect of low cycle fatigue and that of the viscous stress.

Findings

The work identifies that the viscous stress follows an exponential growth behaviour which terminates at a plateau. The plateau value is found to be independent to corrosion exposure and strain rate and hence providing a strong potential for being a characteristic indicator of the behaviour of steel reinforcement under realistic inelastic loading.

Research limitations/implications

The study is limited to S500s grade steel. Further study on different steel grades is necessary to increase the potential of viscous stress.

Originality/value

The significance of this paper is the introduction of viscous stress in an area where traditional approaches of cumulative damage are based on a large number of empirical parameters and assumptions.

Details

International Journal of Structural Integrity, vol. 1 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 28 May 2010

Ch. Alk. Apostolopoulos

The purpose of this paper is to shed light on the uncertainties related to durability prediction of coastal bridges.

Abstract

Purpose

The purpose of this paper is to shed light on the uncertainties related to durability prediction of coastal bridges.

Design/methodology/approach

The paper describes the problems encountered with the Rio‐Antric bridge in Greece.

Findings

Even the most accurate models, especially those traditionally employed, fail to provide secure estimates, cases which create serious questions about suggested life spans. Local conditions, large‐scale effects, construction practise, dynamic phenomena, etc. create such a complex web of parameters able to negate even the most conservative estimates. As such, cathodic protection systems should be employed in every coastal structure as a defence measure.

Originality/value

The paper offers a typical example of how far engineering, material science and construction practise has to go to guarantee that any designed life is accurately met.

Details

International Journal of Structural Integrity, vol. 1 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 2 March 2015

Giacomo Frulla, Gianni Avalle and Vito Sapienza

The purpose of this paper is to investigate the effect of fatigue life reduction of 2024 Al alloy for aerospace components due to the corrosive (exfoliation) environment…

Abstract

Purpose

The purpose of this paper is to investigate the effect of fatigue life reduction of 2024 Al alloy for aerospace components due to the corrosive (exfoliation) environment. Both standard fatigue tests on prior corroded samples and fatigue tests conducted with the samples in corrosive solution are developed to define some guidelines for the inclusion of such effect in design and to improve aircraft life management.

Design/methodology/approach

The effect of corrosion is taken into consideration, introducing specific concentration factors into the life estimation relationship. Differences between fatigue in corroded specimens and fatigue in presence of corrosive environment are emphasized. No crack propagation is considered. Two alternative procedures are considered in the analysis: “a-procedure” based on maximum stress calculated on un-corroded sample section; “b-procedure” based on stress calculated on final residual section, including corrosion.

Findings

Related concentration factors are derived and compared by the experimental results with the aid of an original proposed a “power law”. Typical power law (square kt) has been derived to cope with the coupling effect of fatigue and corrosive environment.

Research limitations/implications

The original approach developed in the paper is based on few samples. For this reason, the conclusions are addressed as tendency behaviour.

Practical implications

The combined effect of fatigue load acting in presence of corrosive environment reveals an important reduction in fatigue life that cannot be determined by means of classical fatigue tests performed on prior corroded samples.

Social implications

Specific design updating procedure can be determined to cope with ageing of structures during service improving structural integrity.

Originality/value

The derivation indicates a substantial equivalence of the considered two procedures both in the case of prior corroded samples and in combined situation. This tendency is consistent with the available data results. Original analytical relations are introduced to manage such kind of combined effect revealing consistency of data also if few samples were tested.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 2
Type: Research Article
ISSN: 0002-2667

Keywords

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