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Previous studies have demonstrated that the behavior of fiber reinforced polymers (FRPs) bonded to metallic utility poles are governed by the following failure modes; yielding of the metallic substrate, FRP tensile rupture, FRP compressive buckling, and debonding of FRP from the substrate. Therefore, an in situ method can be devised for the repair of utility poles, light poles, and mast arms that returns the poles to their original service strength. This thesis investigates the effect of damage due to vehicular impact on metallic poles, and the effectiveness of externally-bonded FRP repair systems in restoring their capacity. Damage is simulated experimentally by rapid, localized load application to pole sections, creating dents ranging in depth from 5 to 45% of the outer diameter. Four FRP composite repair systems were selected for characterization and investigation due to their mechanical properties, ability to balance the system failure modes, and installation effectiveness. Bending tests are conducted on dented utility poles, both unrepaired and repaired. Nonlinear finite element models of dented and repaired pole bending behavior are developed in MSC.Marc. These models show good agreement with experimental results, and can be used to predict behavior of full-scale repair system. A relationship between dent depth and reduced pole capacity is developed, and FRP repair system recommendations are presented

Yes / A numerical method for estimating the curvature, deflection and moment capacity of reinforced concrete beams strengthened with prestressed near-surface-mounted (NSM) FRP bars/strips is presented. A sectional analysis is carried out to predict the moment–curvature relationship from which beam deflections and moment capacity are then calculated. Based on the amount of FRP bars, different failure modes were identified, namely tensile rupture of prestressed FRP bars and concrete crushing before or after yielding of steel reinforcement. Comparisons between experimental results available in the literature and predicted curvature, moment capacity and deflection of reinforced concrete beams with prestressed NSM FRP reinforcements show good agreement. A parametric study concluded that higher prestressing levels improved the cracking and yielding loads, but decreased the beam ductility compared with beams strengthened with nonprestressed NSM FRP bars/strips.

Yes / Flexural performance of concrete beams reinforced with steel–FRP composite bar (SFCB) was investigated in this paper. Eight concrete beams reinforced with different bar types, namely one specimen reinforced with steel bars, one with fiber-reinforced polymer (FRP) bars and four with SFCBs, while the last two with hybrid FRP/steel bars, were tested to failure. Test results showed that SFCB/hybrid reinforced specimens exhibited improved stiffness, reduced crack width and larger bending capacity compared with FRP-reinforced specimen. According to compatibility of strains, materials’ constitutive relationships and equilibrium of forces, two balanced situations, three different failure modes and balanced reinforcement ratios as well as analytical technique for predicting the whole loading process are developed. Simplified formulas for effective moment of inertia and crack width are also proposed. The predicted results are closely correlated with the test results, confirming the validity of the proposed formulas for practical use. / National Natural Science Foundation of China (51678514), China Postdoctoral Science Foundation (2018M642335), the Science and Technology Project of Jiangsu Construction System (2018ZD047), the Cooperative Education Project of Ministry of Education, China (201901273053), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province (2020), the Six Talent Peaks Project of Jiangsu Province (JZ038, 2016) and the Yangzhou University Top Talents Support Project

Yes / Eccentric compression behaviour of reinforced concrete (RC) columns reinforced by steel-FRP composite bars (SFCBs) was investigated through experimental work and theoretical analyses. The tension and compression test results show that SFCBs demonstrate a stable post-yield stiffness. The mechanical properties of the composite reinforcement have a significant influence on eccentric compression behaviour of the reinforced concrete columns, in terms of failure mode, crack width, deformation and bearing capacity. Formulae were also developed to discriminate failure mode and to determine moment magnification factor, bearing capacity and crack width of the columns studied, with the theoretical predictions being in a good agreement with the experimental results. In addition, parametric studies were conducted to evaluate the effects of mechanical properties of reinforcement, reinforcement ratio, eccentricity, slenderness ratio, types of reinforcement and concrete on the eccentric compression behaviour of RC columns. The results show that the compressive performance is significantly improved by using the high performance concrete, i.e. reactive powder concrete (RPC) and engineered cementious composites (ECC). / financial supports of the work by the National Natural Science Foundation of China (51678514), the Natural Science Foundation of Jiangsu Province, China (BK20201436), the China Postdoctoral Science Foundation (2018M642335), the Science and Technology Project of Jiangsu Construction System (2018ZD047), the Deputy General Manager Science and Technology Project of Jiangsu Province (FZ20200869), the Cooperative Education Project of Ministry of Education, China (201901273053), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province (2020), the Six Talent Peaks Project of Jiangsu Province (JZ-038, 2016), the Yangzhou University Top Talents Support Project and the Jiangsu Government Scholarship for Overseas Studies.

Yes / This paper presents test results of eccentrically loaded concrete columns reinforced with steel-fibre-reinforced polymer (FRP) composite bars (SFCBs) subjected to chloride corrosion. The first stage of the experimental work explored the tensile and compressive tests of various reinforcements (SFCBs with different cross section, steel and FRP bars) used in the large reinforced concrete (RC) columns after chloride corrosion with or without sustained stresses. The results showed that the tensile and compressive stress-strain relationships of SFCBs are characterised by stable secondary (post-yield) stiffness. The second stage of the testing investigated the structural performance of RC columns with various amounts and types of reinforcements, slenderness ratio, applied load eccentricity and chloride corrosion rate. The results showed that the effect of reinforcements on eccentric compression behaviour is significant. The deformation and crack width of SFCB RC columns, respectively, decreased by 12.2%~52.6% and 8.5%~71.0%, while the load capacity improved by 0.9%~18.8%, when compared with the corresponding FRP RC columns having the same eccentricity and reinforcement ratio. The use of SFCBs as the reinforcement of RC columns, especially with high reinforcement ratio or SFCBs having high area ratio of inner steel to SFCB, is beneficial to reduce the deflection and crack width as well as improve the bearing capacity utilization coefficients under serviceability limit state.

Yes / This paper numerically investigates flexural performance of Ultra-High Performance Concrete (UHPC) beam reinforced with Steel-Fibre-Reinforced Polymer (FRP) Composite Bars (SFCBs) in terms of flexural stiffness, moment capacity, deflection, ductility and energy dissipation. The effect of various parameters, include the inner steel core area ratio of SFCB, yield strength of inner steel core, elastic modulus and ultimate strength of outer-wrapped FRP, reinforcement ratio, type and strength of concrete were studied. The results demonstrate that the inner steel core area ratio of SFCB, reinforcement ratio and the elastic modulus of SFCB's outer FRP have significant effect on the overall flexural performance of SFCB reinforced UHPC beam. The overall flexural performance of SFCB reinforced UHPC beam is slightly improved by increasing the yield strength of inner steel core of SFCB, but not affected by the ultimate strength of SFCB's outer FRP when specimen occurred compression failure. The results also exhibit that the flexural performance of UHPC beam reinforced with SFCBs is significantly improved when compared to those of reinforced high strength concrete (HSC) beam and normal strength concrete (NSC) beam. The flexural stiffness and the moment capacity of SFCB reinforced UHPC beam at the ultimate point were 2.0 and 2.4 times, respectively, of those of reinforced NSC counterpart. / Natural Science Foundation of Jiangsu Province, China (BK20201436), the China Postdoctoral Science Foundation (2018M642335), the Science and Technology Project of Jiangsu Construction System, China (2018ZD047, 2021ZD06), the Science and Technology Project of Gansu Construction System, China (JK2021-19), the National Natural Science Foundation of China (51678514), the Science and Technology Innovation Fund of Yangzhou University, China (2020-65), the Open Foundation of Jiangsu Province Engineering Research Center of Prefabricated Building and Intelligent Construction, China (2021), the Science and Technology Cooperation Fund Project of Yangzhou City and Yangzhou University, China (YZU212105), the Practice and Innovation Plan for Postgraduates in Jiangsu Province, China (SJCX21_1589), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province, China (2020) and the Deputy General Manager Science and Technology Project of Jiangsu Province, China (FZ20200869). References

Yes / The current paper aimed at investigating the flexural performance of five large-scale continuous concrete beams reinforced by both steel bars and glass fibre reinforced polymer (GFRP). All the studied specimens had the same geometrical dimensions, with 200mm width, 300mm depth, and two identical spans of 2600mm. The quantity of longitudinal steel reinforcement, GFRP reinforcement, and hybrid reinforcement ratio at the top and bottom layers of beams were the key parameters explored in this study. The experimental findings indicated that using the hybrid reinforcement of steel and GFRP in multi-span continuous concrete beams exhibited a ductile behaviour. However, the hybrid ratio of steel bars/GFRP is critical for restricting the extent of moment redistribution ratios. Moreover, using the same hybrid reinforcement ratios at sagging and hogging regions led to a limited moment redistribution. On the other hand, the hybrid beams strengthened by various hybrid ratios in the critical sections of the tested beams demonstrated a remarkable moment redistribution up to 43%. The test results were compared with the available theoretical model and equations for predicting the beams’ moment capacity. It was found that the ACI.440.2R-08 reasonably predicted the flexural capacity of tested beams whereas the Yinghao and Yong equation underestimated the flexural capacity in the hogging sections. It was also shown that using the collapse mechanism with plastic hinges at sagging and hogging sections yielded good predictions for the loading capacity of hybrid reinforced concrete continuous beams.

The objective of this research was to explore and demonstrate the production andperformance of fiber-reinforced polymer (FRP) rebar manufactured on a continuous threedimensionalbraiding machine for use as reinforcement in concrete structures. Differentconfigurations of fiberglass/epoxy composite cylindrical rebar rods were manufactured,embedded in concrete, and tested in axial tension to identify the relationships betweenmanufacturing parameters and tensile pull-out strength of the rebar. The strength of the bondbetween concrete and FRP rebar was investigated using the pull-out test detailed by ACI 440.3R-12. The rebar was a No. 4 size and produced by combining multiple tows of fiberglass/epoxyprepreg to form the core of cylindrical rods which were consolidated using spirally-woundaramid consolidation fibers. The manufactured rebar was cured at 121°C (250°F) as specified bythe material manufacturer, TCR Composites. Preliminary research performed on carbon/epoxyrebar guided the process of developing a test matrix based on multiple variables. Primaryvariables investigated included the nature of the consolidation fiber material (dry vs prepreg),and the use of sand coating as a secondary process. The rebar samples were cast in 200 mm x200 mm x 200 mm (8.0 in x 8.0 in x 8.0 in) concrete cubes to investigate bond strength. A testfixture was designed and fabricated for use on a universal tensile testing machine. Standard 12.7mm (0.5 in) diameter steel rebar and a commercially comparable fiberglass rebar were alsotested to provide baseline values. Measurements were collected at both the free and loaded endsof the rebar with free-end results being a more accurate presentation of rebar bond stress.Results showed that the bond strength was 6-13% higher for the free-end for rebarconsolidated with a dry tow compared to prepreg tow consolidated rebar. When sand was added,dry tow consolidated sand-coated samples showed higher bond stress in the range of 15-26% forthe free-end than samples consolidated with a dry tow but excluded sand coating. Samplesconsolidated with prepreg tow and coated with sand showed higher bond stress in the range of43-58% for the free-end compared to prepreg tow no-sand coating samples. Overall, for therebar manufactured on the 3-D braiding machine, the prepreg tow consolidated rebar samplesrecorded the highest bond strength values with a maximum average bond stress value of 15.2MPa (2.26 ksi). The dry tow sand consolidated rebar recorded a maximum average bond stressvalue of 11.4 MPa (1.65 ksi). The rebar purchased from American Fiberglass Rebar recorded amaximum average bond stress of 12.0 MPa (1.74 ksi) while the maximum average bond stress ofsteel rebar was 13.1 MPa (1.90 ksi). Results demonstrated that quality composite rebar can bemanufactured using the 3-D braiding machine and that consolidating the rebar with a prepregtow and coating the surface with sand resulted in a rebar which bonded well with concretecompared to commercialized FRP and steel rebar.

The objective of this research was to explore and demonstrate the production andperformance of fiber-reinforced polymer (FRP) rebar manufactured on a continuous threedimensionalbraiding machine for use as reinforcement in concrete structures. Differentconfigurations of fiberglass/epoxy composite cylindrical rebar rods were manufactured,embedded in concrete, and tested in axial tension to identify the relationships betweenmanufacturing parameters and tensile pull-out strength of the rebar. The strength of the bondbetween concrete and FRP rebar was investigated using the pull-out test detailed by ACI 440.3R-12. The rebar was a No. 4 size and produced by combining multiple tows of fiberglass/epoxyprepreg to form the core of cylindrical rods which were consolidated using spirally-woundaramid consolidation fibers. The manufactured rebar was cured at 121C (250F) as specified bythe material manufacturer, TCR Composites. Preliminary research performed on carbon/epoxyrebar guided the process of developing a test matrix based on multiple variables. Primaryvariables investigated included the nature of the consolidation fiber material (dry vs prepreg),and the use of sand coating as a secondary process. The rebar samples were cast in 200 mm x200 mm x 200 mm (8.0 in x 8.0 in x 8.0 in) concrete cubes to investigate bond strength. A testfixture was designed and fabricated for use on a universal tensile testing machine. Standard 12.7mm (0.5 in) diameter steel rebar and a commercially comparable fiberglass rebar were alsotested to provide baseline values. Measurements were collected at both the free and loaded endsof the rebar with free-end results being a more accurate presentation of rebar bond stress.Results showed that the bond strength was 6-13% higher for the free-end for rebarconsolidated with a dry tow compared to prepreg tow consolidated rebar. When sand was added,dry tow consolidated sand-coated samples showed higher bond stress in the range of 15-26% forthe free-end than samples consolidated with a dry tow but excluded sand coating. Samplesconsolidated with prepreg tow and coated with sand showed higher bond stress in the range of43-58% for the free-end compared to prepreg tow no-sand coating samples. Overall, for therebar manufactured on the 3-D braiding machine, the prepreg tow consolidated rebar samplesrecorded the highest bond strength values with a maximum average bond stress value of 15.2MPa (2.26 ksi). The dry tow sand consolidated rebar recorded a maximum average bond stressvalue of 11.4 MPa (1.65 ksi). The rebar purchased from American Fiberglass Rebar recorded amaximum average bond stress of 12.0 MPa (1.74 ksi) while the maximum average bond stress ofsteel rebar was 13.1 MPa (1.90 ksi). Results demonstrated that quality composite rebar can bemanufactured using the 3-D braiding machine and that consolidating the rebar with a prepregtow and coating the surface with sand resulted in a rebar which bonded well with concretecompared to commercialized FRP and steel rebar.