Influence of cross section loss on the stress-strain characteristics of corroded quenched and self-tempered reinforcing bars

Haefliger, Severin; Kaufmann, Walter

doi:10.1016/j.conbuildmat.2021.122598

Cited by 13 publications

(10 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This deviation can be explained by the interaction of distinct material layers with different microstructures present in QST reinforcing bars: when the perlitic/ferritic core, which has a pronounced yield plateau, reaches its yield limit, the outer martensitic layer, without yield plateau but having a higher yield limit, is still elastic. This causes the slope of the stress-strain curve to decrease before a clear yield plateau is reached [47].…”

Section: Normal Stresses Of Reinforcing Steelmentioning

confidence: 99%

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Lemcherreq

Galkovski

Mata‐Falcón

et al. 2022

Sensors

Self Cite

View full text Add to dashboard Cite

Distributed fibre optical sensing (DFOS) is increasingly used in civil engineering research. For reinforced concrete structures, almost continuous information concerning the deformations of embedded reinforcing bars can be obtained. This information enables the validation of basic and conventional assumptions in the design and modelling of reinforced concrete, particularly regarding the interaction of concrete and reinforcing bars. However, this relatively new technology conceals some difficulties, which may lead to erroneous interpretations. This paper (i) discusses the selection of sensing fibres for reinforced concrete instrumentation, accounting for strain gradients and local anomalies caused by stress concentrations due to the reinforcing bar ribs; (ii) describes suitable methods for sensor installation, strain acquisition and post-processing of the data, as well as determining and validating structurally relevant entities; and (iii) presents the results obtained by applying DFOS with these methods in a variety of experiments. The analysed experiments comprise a reinforced concrete tie, a pull-out test under cyclic load, and a flexural member in which the following mechanical relevant quantities are assessed: the initial strain state in reinforcing bars, normal and bond shear stresses, deflections as well as forces. These applications confirm the benefit of DFOS to better understand the bond behaviour, but also demonstrate that its application is intricate and the results may lead to erroneous conclusions unless evaluated meticulously.

show abstract

Section: Normal Stresses Of Reinforcing Steelmentioning

confidence: 99%

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Lemcherreq

Galkovski

Mata‐Falcón

et al. 2022

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…While the small grooves have a negligible influence on the behaviour of the reinforcing bars in most cases, the cross-sectional loss might be significant for bars of small diameters. The material properties of reinforcing bars with distinct microstructure (e.g., quenched and self-tempered bars) might also be slightly modified, since the groove removes part of the outer (martensitic) layer of the bar [31]. Therefore, whenever stresses or forces are to be derived from the measured strains in bars of small diameters, it is good practice to determine the steel's constitutive law on grooved samples [17].…”

Section: Selection and Installation Of Sensing Fibres For Reinforcing Steel Instrumentationmentioning

confidence: 99%

“…In the second production process, steel is quenched, i.e., cooled down quickly with water (or air in some cases), after being hot-rolled, in such a way that the core remains hot enough to temper the outer layer after cooling. As a result, the core is a homogenous ferrite and perlite mixture with high ductility, while a martensitic external layer with higher strength and a bainite transition zone between the two [31] form. Unless coiled, quenched and self-tempered (QST) reinforcing steel exhibits a distinct yield plateau after the elastic phase, followed by hardening.…”

Section: Measurement Of Reinforcing Steel Strainsmentioning

confidence: 99%

Fundamental Studies on the Use of Distributed Fibre Optical Sensing on Concrete and Reinforcing Bars

Galkovski

Lemcherreq

Mata‐Falcón

et al. 2021

Sensors

Self Cite

View full text Add to dashboard Cite

Distributed fibre optical sensing (DFOS) allows for quasi-continuous strain measurement in a broad range of gauge lengths and measurement frequencies. In particular, Rayleigh backscatter-based coherent optical frequency domain reflectometry has recently registered a significant application increase in structural concrete research and monitoring thanks to its numerous merits, such as high resolution and low invasiveness. However, it is not a plug-and-play technique. The quality of the acquired data depends highly on the choice of the fibre optical sensor and the methods of instrumentation and post-processing. Furthermore, its unprecedented resolution and sensitivity allow capturing local effects not well documented so far. This paper analyses the suitability of DFOS based on Rayleigh backscatter for reliably measuring strains and discusses the origin and structural relevance of local variations in the results. A series of experimental investigations are presented, comprising tensile tests on bare reinforcing bars and concrete compression tests. A critical analysis of the results leads to a best practice for applying DFOS to reinforcing bars and concrete, which establishes a basis for reliable, accurate measurements in structural concrete applications with bonded reinforcement.

show abstract

“…This results in a reinforcing bar combining the favourable material characteristics but can lead to a considerable strength reduction in case of uniform corrosion, as was shown by various studies. 4,17,18 However, it was pointed out that the change in stressstrain characteristics is less pronounced for pitting corrosion compared with uniform corrosion. 18 The load-deformation behaviour of a reinforcing bar containing a corrosion pit is significantly influenced by the pit morphology.…”

Section: Single Reinforcing Bar (Microscopic Level)mentioning

confidence: 99%

“…4,17,18 However, it was pointed out that the change in stressstrain characteristics is less pronounced for pitting corrosion compared with uniform corrosion. 18 The load-deformation behaviour of a reinforcing bar containing a corrosion pit is significantly influenced by the pit morphology. 2,4,5,7 The stress trajectories are deviated due to the local cross-section reduction, leading to a three-dimensional stress state in the pit region (Figure 1a).…”

Section: Single Reinforcing Bar (Microscopic Level)mentioning

confidence: 99%

Corroded Tension Chord Model: Load‐deformation behavior of structures with locally corroded reinforcement

Haefliger

Kaufmann

2021

Structural Concrete

Self Cite

View full text Add to dashboard Cite

Localised corrosion may considerably impair the load‐bearing and deformation capacity of reinforced concrete structures. The Corroded Tension Chord Model allows investigating the related effects. The model combines the effects of tension stiffening and strain localisation due to a local cross‐section loss to calculate the load‐deformation behaviour of tension members and entire structural elements containing locally corroded reinforcing bars on a sound mechanical basis. Based on simple equilibrium considerations, the critical loss of cross‐sectional area is introduced, beyond which most of a reinforcing bar's ductility or a structure's deformation capacity, respectively, is lost. For conventional European reinforcing steel, even small cross‐section losses may be sufficient to impair ductility drastically. Illustrative calculations on structural elements with various spatial corrosion distributions but identical mean cross‐section loss reveal that the load‐deformation behaviour strongly depends on the specific corrosion parameters: Structures with few heavily corroded reinforcing bars seem to be less critical regarding strength and deformation capacity than structures with many slightly corroded reinforcing bars.

show abstract

Influence of cross section loss on the stress-strain characteristics of corroded quenched and self-tempered reinforcing bars

Cited by 13 publications

References 21 publications

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Application of Distributed Fibre Optical Sensing in Reinforced Concrete Elements Subjected to Monotonic and Cyclic Loading

Fundamental Studies on the Use of Distributed Fibre Optical Sensing on Concrete and Reinforcing Bars

Corroded Tension Chord Model: Load‐deformation behavior of structures with locally corroded reinforcement

Contact Info

Product

Resources

About