TY - JOUR
T1 - Experimental study on mixed mode-I & II bond behavior of CFRP-to-steel joints with a ductile adhesive
AU - Zhao, Jun
AU - Fang, Jian
AU - Yang, Yongming
AU - Zhang, Shishun
AU - Biscaia, Hugo
N1 - Funding Information:
The authors would like to thank the financial support provided by the National Natural Science Foundation of China (NSFC) with Grant No. 52008378 , the Program for Innovative Research Team of Education Ministry of China ( IRT_16R67 ) and Fundação para a Ciência e Tecnologia (FCT), Portugal for the partial funding of this work under the strategic project UIDB/ EMS/00667/2020.
Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/3
Y1 - 2023/3
N2 - Utilizing ductile adhesive on CFRP-reinforced steel structures makes the bonded interface with good resistance to dynamic and fatigue loading, which is suitable for the rehabilitation of steel bridges. Currently, considerable studies on the aspect of the CFRP–steel interface are focused only on mode-II loading, ignoring the effects of mode-I loading which could lead to a catastrophic collapse of the retrofitted structures. In the present paper, modified CFRP-to-steel bonded double overlapped joints with various initial peeling angles (θ) were manufactured in order to consider mode-I loading and study the bond behavior of CFRP-to-steel joints under mixed mode-I&II loading. The results showed that the bonded side with weaker adhesion between CFRP and adhesive debonded first and presented a CFRP-adhesive interfacial debonding mode, while the debonding of the other side was delayed and showed a cohesive failure mode in the adhesive. The bond shear stress vs. slip relationship of the debonded side showed to have a bi-linear trend in which the bond strength and interfacial fracture energy were low whilst the other side showed a trapezoidal relationship with a constant plastic plateau and with higher interfacial fracture energy. It was found that sudden debonding caused a quick propagation in the CFRP strain as well as on the global interfacial slip of the joints. It was also found that the peeling angle had significantly deteriorated the local bond response in mode-II, i.e. the trapezoidal bond shear stress vs. slip relationship in the joints with θ=0° shifted to a bi-linear relationship in the joints with θ=1°, θ=2° and with θ=3° in which the bond strength, slip and fracture energy, all decreased very much. Moreover, with θ=4° was experimentally determined as the threshold angle from which the associated mode-I loading can, per se, separate the CFRP from steel.
AB - Utilizing ductile adhesive on CFRP-reinforced steel structures makes the bonded interface with good resistance to dynamic and fatigue loading, which is suitable for the rehabilitation of steel bridges. Currently, considerable studies on the aspect of the CFRP–steel interface are focused only on mode-II loading, ignoring the effects of mode-I loading which could lead to a catastrophic collapse of the retrofitted structures. In the present paper, modified CFRP-to-steel bonded double overlapped joints with various initial peeling angles (θ) were manufactured in order to consider mode-I loading and study the bond behavior of CFRP-to-steel joints under mixed mode-I&II loading. The results showed that the bonded side with weaker adhesion between CFRP and adhesive debonded first and presented a CFRP-adhesive interfacial debonding mode, while the debonding of the other side was delayed and showed a cohesive failure mode in the adhesive. The bond shear stress vs. slip relationship of the debonded side showed to have a bi-linear trend in which the bond strength and interfacial fracture energy were low whilst the other side showed a trapezoidal relationship with a constant plastic plateau and with higher interfacial fracture energy. It was found that sudden debonding caused a quick propagation in the CFRP strain as well as on the global interfacial slip of the joints. It was also found that the peeling angle had significantly deteriorated the local bond response in mode-II, i.e. the trapezoidal bond shear stress vs. slip relationship in the joints with θ=0° shifted to a bi-linear relationship in the joints with θ=1°, θ=2° and with θ=3° in which the bond strength, slip and fracture energy, all decreased very much. Moreover, with θ=4° was experimentally determined as the threshold angle from which the associated mode-I loading can, per se, separate the CFRP from steel.
KW - Bonded joints
KW - CFRP
KW - Ductile adhesive
KW - Mixed mode-I&II loading
KW - Steel
UR - http://www.scopus.com/inward/record.url?scp=85146299179&partnerID=8YFLogxK
U2 - 10.1016/j.tws.2023.110532
DO - 10.1016/j.tws.2023.110532
M3 - Article
AN - SCOPUS:85146299179
SN - 0263-8231
VL - 184
JO - Thin-Walled Structures
JF - Thin-Walled Structures
M1 - 110532
ER -