Title:
Flexural Behavior of Carbon Fiber-Reinforced Polymer Partially Bonded Reinforced Concrete Beams with Different Anchorage Methods
Author(s):
Qi Cao, Xingchao Wang, Zhimin Wu, Rongxiong Gao, and Xin Jiang
Publication:
Structural Journal
Volume:
121
Issue:
1
Appears on pages(s):
61-74
Keywords:
anchorage; concrete beam; flexural performance; partially bonded carbon fiber-reinforced polymer (CFRP); unbonded ratio
DOI:
10.14359/51739185
Date:
1/1/2024
Abstract:
Carbon fiber-reinforced polymer (CFRP) is a widely used material
for reinforced concrete (RC) beam strengthening. Because of
exposure to severe environments and improper construction, CFRP
sheets may separate from the bottom of RC beams. To analyze
the influence of this type of interfacial defect on the mechanical
properties of RC beams quantitatively and provide a reference for
the rehabilitation of structures, this paper investigates the flexural
properties of RC beams strengthened with partially bonded CFRP
by experiments and analytical studies. To measure the degree of
unbonded CFRP, a new parameter called the unbonded ratio was
established, which is defined as the ratio of unbonded length to the
total length of strengthening CFRP in the tension zone. Twenty-six
RC beams were fabricated and tested in the present study, and the
experimental variables were the unbonded ratio, thickness of the
CFRP sheet, and anchorage method (vertical U-jacket, inclined
U-jacket, and mechanical plate). The cracking load, ultimate load,
load-midspan deflection curve, ductility, crack pattern, and failure
modes of these specimens are discussed. Also, the coupling effect
of the unbonded CFRP and anchorage method on the flexural
performance of strengthened beams was investigated. Test results
indicated that the ultimate load decreased with the increase of
the unbonded ratio before the unbonded ratio reached its critical
value. It was also found that the mechanical-plate anchorage and
inclined U-jackets were superior to traditional vertical U-jackets
in terms of load-carrying capacity and flexural stiffness and postponed the debonding of CFRP. Finally, a theoretical model for the ultimate load of RC beams strengthened with inclined U-jackets
was proposed, which showed a good agreement with the test results.