The Effects of Bond–Slip Laws on the Debonding Failure and Behavior of Flexural Strengthened RC Slabs in Hybrid FRP Retrofit Systems

The hybrid retrofit system using FRP and concrete overlay applied on the top of slabs has proven effective in strengthening and overcoming logistical constraints, compared with conventional strengthening techniques using externally bonded composite materials to the underside of the slabs. Neverthele...

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Bibliographic Details
Published in:Materials 2022-10, Vol.15 (21), p.7453
Main Authors: Nguyen, Huy Q., Nguyen, Tri N. M., Lee, Do Hyung, Kim, Jung J.
Format: Article
Language:English
Subjects:
Bearing strength
Bonding strength
Composite materials
Concrete
Cost control
Debonding
Ductility
Failure
Failure mechanisms
Finite element method
Hybrid systems
Load
Load carrying capacity
Mechanical properties
Reinforced concrete
Retrofitting
Sensitivity analysis
Shear stress
Slabs
Slip
Stiffness
Strengthening
Stress concentration
Tensile strength
Yield stress
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Summary:The hybrid retrofit system using FRP and concrete overlay applied on the top of slabs has proven effective in strengthening and overcoming logistical constraints, compared with conventional strengthening techniques using externally bonded composite materials to the underside of the slabs. Nevertheless, the performance of retrofitted slabs is governed by debonding failure due to the low bond strength between CFRP and concrete overlay. Thus, this study investigates the behavior of flexural strengthened slabs with FRP retrofit systems and the effect of bond–slip laws on debonding failure. Firstly, two full-scale RC slabs with and without a retrofit system were tested in a four-point bending setup as the control specimens. Then, the same retrofitted slab was simulated by utilizing the commercial program ABAQUS. A sensitivity analysis was conducted to consider the influence of bond–slip laws to predict the failure mechanism of the retrofitted slabs based on load–deflection relationships. The results showed that the strengthened slab enhanced the load-carrying capacity by 59%, stiffness by 111%, and toughness by 29%. The initial stiffness of 0.1K0 and maximum shear stress of 0.13τmax, compared with the corresponding values of Neubauer’s and Rostasy’s bond–slip law, can be used to simulate the global response of the retrofitted slab validated by experiment results.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15217453