Anchorage of plain, naturally corroded reinforcement bars with end-hooks
Typ
Examensarbete för masterexamen
Program
Publicerad
2021
Författare
Zheng, Litong
Liu, Sining
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Following the developments since 1960, plain reinforcement bars have been replaced
by ribbed reinforcement bars in the design of concrete structures. However, some
of the existing old structures with plain reinforcement bars are still in use and
there is insufficient knowledge available for the assessment of structures with plain
reinforcement bars.
The aim of this thesis was to evaluate the anchorage capacity of naturally corroded
plain reinforcement bars with end-hooks. The studied specimens were earlier cut
from edge beams of a decommissioned bridge. There were two types of beams:
with one or two pairs of hooks. Three-point bending tests of the beams had been
carried out before this thesis project. Digital Image Correlation was used to monitor
deflections and crack developments. In this thesis, the structural behavior of both
types of beams was evaluated. The yield penetration and corrosion level of plain
reinforcement bars with end-hooks were evaluated from 3D scanned data. Further,
the bond stress in the yielded zone and the force anchored by the hooks were assessed.
Finally, the experimental results were compared to the design capacity in accordance
with two different available codes, BBK 04[3] and ACI[1].
In comparison, the beams with two pairs of hooks showed a larger load-carrying
capacity. The end-hook of beams with one pair of hooks managed to carry the
yield force in some cases, while for the beams with two pairs of hooks, shear failure
limited the deformation capacity of the beams. The results showed that the average
corrosion level varied from 0% to 2%. The bond stress in the yielded zone was
found to vary between 0 MPa and 4.5 MPa. The force anchored by the hooks varied
depending on the assumed value of the bond stress in the unyielded zone. For an
assumed bond stress ranging from 1 MPa to 12 MPa, the evaluated force anchored
by the hooks was similar in both types of beams and varied between 32 kN and 53
kN. The calculated force anchored by the hooks in the experiments was on average
84% and 64% of the code results according to BBK 04[3] and ACI[1], respectively.
Beskrivning
Ämne/nyckelord
Natural corrosion, plain reinforcement bars, reinforced concrete, anchorage, bond stress, DIC, 3D scanning