| 11. |
- Blomfors, Martin, et al.
(författare)
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Reliability analysis of corroded reinforced concrete beam with regards to anchorage failure
- 2019
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Ingår i: Life-Cycle Analysis and Assessment in Civil Engineering. - : CRC Press/Balkema. - 9781138626331 - 9781351857574 ; , s. 337-344, s. 337-344
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Konferensbidrag (refereegranskat)abstract
- Reinforcement corrosion is a common problem in reinforced concrete infrastructure today, and it is expected to increase in the future. To simply replace the corroded structures with new ones requires large resources, both in financial and environmental terms. Therefore it is important that existing structures are used to their full potential, also after the onset of corrosion. This paper presents a reliability study of the anchorage capacity of a reinforced concrete beam including reinforcement corrosion. The sensitivity of the different input parameters is also studied. As expected, the results show that the reliability is reduced with corrosion; the magnitude depends to a large extent on the modelling uncertainty used for the bond model for corroded reinforcement. The sensitivity analysis shows an influence of corrosion also on the sensitivities of the input parameters, which is expected based on the properties of the underlying bond model. This paper demonstrates that probabilistic evaluations give valuable insight of the reliability, which can be used to prolong the service-life of existing infrastructure and save both money and the environment.
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| 12. |
- Blomfors, Mattias, 1990, et al.
(författare)
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Reliable engineering assessments of corroded concrete structures
- 2017
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Ingår i: Nordic Concrete Research : Proceedings of the XXIII Nordic Concrete Research Symposium, Aalborg, Denmark, 21-23 August, 2017 - Proceedings of the XXIII Nordic Concrete Research Symposium, Aalborg, Denmark, 21-23 August, 2017. ; , s. 245-248
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Konferensbidrag (refereegranskat)abstract
- Corrosion of steel reinforcement is a large and increasing problem for reinforced concrete structures. Simple and reliable assessment methods are required to use the full capacity of existing infrastructure. In this paper, a reliable engineering assessment method is outlined. A model for anchorage has been developed and verified against a large database of bond tests. Also the influence of corrosion on the bending and shear capacity is to be included, and a probabilistic model will be established. The outcome of this work will enable practising engineers to perform reliable assessments of concrete structures with corroded reinforcement.
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| 13. |
- Coronelli, Dario, et al.
(författare)
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Bond Strength of Highly Corroded Reinforcement and Cover Delamination
- 2012
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Ingår i: Proceeding of the Fourth International Conference on Bond in Concrete. ; 1, s. 469-474
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Konferensbidrag (refereegranskat)abstract
- A recent experimental and analytical research program (Zandi et al., 2011-a, b) provided bond strength values for highly corroded bars. The test program included both main reinforcement and stirrup corrosion. These results must be compared to the rather wide but scattered database of test results in this field. Two relevant sources for comparison are the indications of FIB MC2010, based on the existing literature, and some recently published test results (Regan and Kennedy Reid, 2009). The latter simulated the delamination of the concrete cover by casting the concrete either flush to the bar surface or at mid-barrel i.e. the bars had either no cover or even were partly external to the concrete; the reinforcement was not corroded. The paper summarizes the tests by the authors and develops the comparison with the other studies. The conclusions discuss the choice of bond strength values for the assessment of existing structures and future research outlooks.
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| 14. |
- Coronelli, Dario, et al.
(författare)
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FIB model code 2020 - Structural models for existing concrete structures
- 2018
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Ingår i: FIB 2018 - Proceedings for the 2018 fib Congress: Better, Smarter, Stronger. - 2617-4820. ; , s. 3019-3040
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Konferensbidrag (refereegranskat)abstract
- The paper gives an overview of this ambitious project, which builds upon the achievements of fib MC2010, the previous edition of the fib Model Code. MC2020 will deal with both the design of new structures and all the activities associated with the through-life management and care of existing concrete structures, including matters such as inservice assessment and interventions to extend the life / improve the performance of these structures. Particular attention will be paid to issues specific to existing structures. Relevant structural models are planned for the determination of their load capacity / structural reliability, serviceability, remaining service life etc taking account of: • Load-carrying behaviour not considered in design, such as compressive membrane action and the increase in concrete compressive strength with time due to ongoing hydration effects. • Load-carrying behaviour in deteriorated members and structures, which is different to those members which have not experienced deterioration. The paper gives consideration to corrosion of reinforced concrete members and prestressed concrete members, as well as to the effects of other forms of deterioration such as alkali-aggregate reactions and frost damage. The paper also notes some of the differences between the approaches employed for Life Cycle Assessment and Design (LCA / LCD) based on deterioration models, and the assessment of the present condition of the structure (i.e. at a given moment in time) which utilise mechanical models to represent the influences of the deterioration processes which are active.
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| 15. |
- Coronelli, Dario, et al.
(författare)
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Severely Corroded RC with Cover Cracking
- 2013
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Ingår i: Journal of Structural Engineering. - 0733-9445 .- 1943-541X. ; 139:2, s. 221-232
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Tidskriftsartikel (refereegranskat)abstract
- It is not uncommon that cover cracking, spalling, and delamination occur in many corroding RC structures. Previous research has mainly been concerned with corrosion levels leading to cover cracking along the main reinforcement, whereas corrosion of stirrups is often overlooked. Corrosion phenomena, including stirrup corrosion, were studied in an experimental investigation presented in this paper. High levels of corrosion were reached, up to 20% of the main bars and 34% of the stirrups legs. The occurrence of crack initiation, propagation, and cover delamination were examined. The specimens had the shape of a beam end and were corroded with an accelerated method; an imposed current was used, taking care to keep the current density as low as practically possible for the duration of the laboratory testing. The effects of this process were compared with those of natural corrosion using models from the literature. The location of the bar, middle and corner placement, the amount of transverse reinforcement, and the corrosion level of longitudinal reinforcement and of transverse reinforcement were studied. The results concerning the concrete cracking in the experimental campaign are presented. The crack patterns and widths were analyzed, showing differences between specimens with or without stirrups and whether stirrups were corroding. Finally, the effect of corrosion was simulated as the expansion of corrosion products in a finite-element (FE) model, and the results, mainly the crack pattern and width, were compared with the test results. The conclusions addressed the importance of taking into consideration both high corrosion levels and corrosion of stirrups for the assessment of deteriorated structures.
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| 16. |
- Coronelli, Dario, et al.
(författare)
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Severely Corroded Reinforced Concrete with Cover Spalling: Part 1. Crack Initiation, Crack Propagation and Cover Delamination
- 2010
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Ingår i: RILEM Bookseries. - 2211-0844 .- 2211-0852. ; 5, s. 195-205
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Konferensbidrag (refereegranskat)abstract
- In many corroding RC structures, it is not uncommon that cover spalling and delamination have occurred. Previous research has been mainly concerned with lower corrosion levels leading to cover cracking. Moreover, the main focus of the available knowledge concerns the corrosion of the main reinforcement; while the corrosion of the stirrups is often overlooked. In an experimental investigation, corrosion attack causing crack initiation, propagation and cover delamination are measured. The specimens have the shape of a beam-end and are corroded with an accelerated method. The location of the bar, middle and corner placement; the amount of transverse reinforcement; the corrosion level of longitudinal reinforcement and of transverse reinforcement are studied. The specimens after corrosion are also used in pull-out bond tests; the results are presented in a companion paper subtitled “Part 2. Anchorage Capacity”. The first test results of the ongoing experimental campaign are presented. The crack patterns are analysed, showing differences between specimens with or without stirrups and when stirrups are corroding or not. Finally, the effect of corrosion was simulated as the expansion of corrosion products in a finite element model and the results, mainly the crack pattern, were compared with the test results. The conclusions address the importance of taking into consideration both high corrosion levels and the corrosion of the stirrups for the assessment of deteriorated structures.
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| 17. |
- Coronelli, Dario, et al.
(författare)
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Structural modelling of the response of deteriorated rc and psc members: Levels of approximation for model code 2020
- 2021
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Ingår i: fib Symposium. - 2617-4820. ; , s. 283-292
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Konferensbidrag (refereegranskat)abstract
- The assessment of reinforced concrete structures affected by deterioration such as reinforcement corrosion involves the use of different models, according to different scientific and technical purposes. The paper presents a framework for structural modelling approaches previously developed by the authors to fit in the concept of Levels of Approximation for Model Code 2020. The concept is here extended to include different accuracy levels in deterioration modelling. The paper moves from simple strut and tie models to analytical models and finite element numerical studies. The possibility of an extension of the framework to modelling the freeze-thaw deterioration is highlighted. The conclusions highlight the available techniques and the needs for research developments.
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| 18. |
- E. Ransom, Elliot, et al.
(författare)
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A UAV-based platform for automated inspection of cracked concrete surfaces
- 2019
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Ingår i: Structural Health Monitoring 2019: Enabling Intelligent Life-Cycle Health Management for Industry Internet of Things (IIOT) - Proceedings of the 12th International Workshop on Structural Health Monitoring. - Lancaster, PA : DEStech Publications, Inc..
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Konferensbidrag (refereegranskat)
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| 19. |
- Fahimi, S., et al.
(författare)
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A novel method for implementation of corrosion-induced cracks in the finite element models of reinforced concrete structures
- 2021
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Ingår i: Scientia Iranica. - 1026-3098 .- 2345-3605. ; 28:3 A, s. 1079-1095
-
Tidskriftsartikel (refereegranskat)abstract
- Currently, there is a clear need for reliable procedures for condition assessment and service-life evaluation of existing infrastructures. Advanced 3D Nonlinear Finite Element (3D NLFE) analysis has proven to be capable of describing the behavior of reinforced concrete provided that detailed and appropriate condition assessment data are available. The present study aims to review and compare different procedures for coupling 3D NLFE analysis with condition assessment data to model corrosion induced cracking, and, consequently to find a method with better accuracy, less computational cost, and improved robustness. This paper introduces a new method for adding cracked elements directly to the finite element model, called Re-FEM. The force-displacement response, ultimate crack pattern, and failure mode from this model are compared with four other methods for a pull out test case on specimens under an accelerated corrosion process. Using this method, the force displacement response for the corroded specimens was overestimated by about 70%. However, the trend was promising and the failure mode and crack pattern were correct. Moreover, the analysis continued after the peak point in the force-displacement curve, which makes it possible to monitor the behavior of the specimen in the softening regime.
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| 20. |
- Fahimi, Shayan, et al.
(författare)
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Replication of Crack Pattern in FE Analysis Based on Discretization of Tension Softening Curves
- 2017
-
Ingår i: Nordic Concrete Research. - 0800-6377. ; 56:1, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Today, there is an increasing need for reliable methods for condition assessment and service-life evaluation of existing structures. Although advanced 3D Nonlinear Finite Element (3D NLFE) analysis has proven to be capable of describing the behavior of reinforced concrete in a comprehensive way, the analysis results are difficult to couple with visual inspection data such as cracking and spalling. Moreover, 3D NLFE programs are numerically expensive and incomprehensible for full-scale practical applications. Thus, the present study aims to couple 3D NLFE analysis with condition assessment data, and consequently to increase the accuracy, to optimize the computation time and to improve robustness of such analyses.
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