Load‐deformation behavior of locally corroded reinforced concrete retaining wall segments: Experimental results
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Date
2023-02
Publication Type
Journal Article
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Abstract
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.
The experiments confirmed that the ultimate load and the corresponding
deformation strongly differ depending on the corrosion pit distribution, even
among specimens with equal mean cross-section loss. Furthermore, it was
found that the deformation increase due to corrosion damage depends on the
loading and, hence, on the compaction of the backfill. The observed deformation
increase ranged between 0.8 and 1.4 mm per meter height at 40% crosssection
loss, with loose soil causing a larger deformation increase. The load
transfer between the damaged and undamaged reinforcing bars was found to
take place in the first two crack elements above the construction joint. Local
bending moments occurred in the reinforcing bars in the vicinity of the corrosion
pits due to the shift of the center of gravity of the bar at the pit. Fiber optic
strain sensing allowed visualizing the bending moment decrease in the embedded
part of the damaged bars as a consequence of a lateral bearing pressure.
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published
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Journal / series
Volume
24 (1)
Pages / Article No.
288 - 317
Publisher
Wiley
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Date collected
Date created
Subject
Corrosion; Deformation capacity; Hybrid testing; Large-scale experiments; Load-deformation behaviour; Pit geometry; Pitting; Retaining walls
Organisational unit
09469 - Kaufmann, Walter / Kaufmann, Walter
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Is cited by: https://doi.org/10.3929/ethz-b-000602335