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

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Local reinforcement corrosion damage reduces the load-bearing capacity of reinforced concrete structures and, even more severely, their deformation capacity. This problem is of particular concern for cantilever retaining walls, whose loading is dominated by earth pressure and hence, depends on the wall deformations. With a limited deformation capacity at the ultimate limit state due to the locally corroded reinforcement, the earth pressure may not drop to its reduced value typically assumed in design, and simultaneously, the structural resistance may be severely impaired by the cross-section loss. Load redistributions are impeded since retaining walls are statically determined vertically and typically segmented longitudinally. This increases the risk that affected structures collapse, exhibiting a brittle failure. The situation is aggravated by the fact that the wall deformations prior to failure are too small to be detected by conventional monitoring, as indicated by a previous study. To improve the basis for quantifying the related risks and the magnitude of prefailure deflections, this study investigates the load-deformation behavior of cantilever retaining walls affected by local pitting corrosion, focusing on (i) the influence of the corrosion pit distribution among different reinforcing bars on the load-bearing and deformation capacity and (ii) the interdependence of corrosion, reduced deformation capacity and deformation-dependent loading. To this end, eight large-scale experiments on retaining wall segments were conducted in the Large Universal Shell Element Tester (LUSET), simulating the lower part of a 4.65-m-tall cantilever retaining wall. Five specimens contained initial damage (pitting corrosion simulated by a spherical mill). In the remaining three specimens, artificial corrosion damage was induced during the experiments. For two of the latter specimens, the loading was adapted in real-time control depending on their deformation to simulate the decreasing earth pressure. These are the first large-scale hybrid tests in the field of corrosion research to our knowledge.Discussion on this paper must be submitted within two months of the print publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.

{normalζ}_{i} = 0.45

or 10% of bars at

{normalζ}_{i} = 0.9

).…”

Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 81%

Section: Experimental Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Load‐deformation behavior of locally corroded reinforced concrete retaining wall segments: Experimental results

Haefliger

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2022

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

Haefliger

Kaufmann

2021

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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.

Prediction of the monotonic load–displacement curve of slender RC beams with corroded transverse and longitudinal reinforcements

Rossi

Spinella

2023

The present paper proposes a mechanical model for the prediction of the response of slender reinforced concrete beams with corroded transverse and longitudinal reinforcements. The proposed model is based on the Modified Compression Field Theory and is able to predict the load–displacement curve of members subjected to monotonic displacement‐controlled tests up to their peak load. The corrosion‐damage effects are considered by means of an effective width of the beam and by means of reduced values of both cross‐sectional area and strain capacity of steel bars. The accuracy of the model is evaluated by comparison with results of tests reported in the literature. Moreover, a simple relation is suggested for the estimate of the shear strength of reinforced concrete beams with low values of the effective geometric percentage of (corroded) stirrups.