Parametric investigation of continuous beams strengthened with near surface mounted FRP bars
•NSM FRP-strengthened RC continuous members are rarely studied.•A comprehensive nonlinear finite element analysis is conducted in ABAQUS.•Variables studied: hogging/sagging FRP reinforcement ratio (ρh/ρs), FRP bar length, span ratio, among others.•Recommended ρh/ρs is found to be 1.5.•An FRP bar len...
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| Published in: | Engineering structures Vol. 293; p. 116619 |
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| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier Ltd
15-10-2023
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | •NSM FRP-strengthened RC continuous members are rarely studied.•A comprehensive nonlinear finite element analysis is conducted in ABAQUS.•Variables studied: hogging/sagging FRP reinforcement ratio (ρh/ρs), FRP bar length, span ratio, among others.•Recommended ρh/ρs is found to be 1.5.•An FRP bar length in the hogging and sagging zones of 80% of span is recommended.
This study evaluates the near surface mounted fiber-reinforced polymer (FRP) reinforcement technique for strengthening continuous reinforced concrete beams. A three-dimensional finite element model was developed and validated with a recent experimental study. The model incorporates robust features, including concrete nonlinear behavior, debonding and slipping of FRP bars, and various failures. It was able to capture the ultimate load (Pu) with maximum deviation of 7%, beam’s load–deflection curves, load–strain responses in rebar and concrete, and various failure modes. A parametric study was conducted and showed that failure mode changes from concrete shear to FRP bar debonding at concrete compressive strength fc’of 20–30 MPa, with a 26–52% increase in Pu relative to the un-strengthened beam. Varying the hogging/sagging FRP reinforcement ratio (ρh/ρs) from zero to 2.0 results in a 39% increase in Pu and a change of failure mode. A value of 1.5 is recommended for ρh/ρs. Also, the synergistic effects of NSM FRP and internal steel reinforcements were studied. An FRP bar length in the hogging and sagging zones of 80% the beam span was found to be sufficient to mitigate debonding and thus is recommended. Pu did not vary significantly with the span ratio for two-span continuous beams. A design expression for the debonding strain in FRP bars based on the American Concrete Institute design guide was assessed and a further refined model is developed. |
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| ISSN: | 0141-0296 1873-7323 |
| DOI: | 10.1016/j.engstruct.2023.116619 |