Corrosion of steel structures is unavoidable and the structural performance decreases dramatically due to the corrosion. As a repairing method for corroded steel members, bonding carbon fiber sheets with resin had bee...Corrosion of steel structures is unavoidable and the structural performance decreases dramatically due to the corrosion. As a repairing method for corroded steel members, bonding carbon fiber sheets with resin had been developed. The purpose of this study is to propose the flexural strengthening method for steel members by using CFRP （carbon fiber reinforced polymer） strand sheets. In order to clarify the stiffening effect and the debonding characteristics of CFRP strand sheets, and to optimize the strengthening design specifications, the flexural tests using high tension steel beams strengthened with CFRP strand sheets are performed. Two cases of experiments are carried out. In Experiment 1, the result from previous research is reflected in the strengthening design. Moreover in Experiment 2, the debonding characteristics obtained from Experiment 1 are reflected. As a result, it was clarified that CFRP strand sheets have stiffening effect equivalent to the theoretical value and its debonding property is practically high enough when FRP （fiber reinforcement polymer） sheets have an appropriate bonding length.展开更多
The potential of externally applied FRP （fiber-reinforced plastic） sheets, being employed in retrofitting schemes aimed to repair and strengthen RC （reinforced concrete） structural elements damaged by prototype st...The potential of externally applied FRP （fiber-reinforced plastic） sheets, being employed in retrofitting schemes aimed to repair and strengthen RC （reinforced concrete） structural elements damaged by prototype strong earthquakes, is presented and discussed in this study. The limitation of the debonding mode of failure of these FRP sheets is highlighted and the necessity to develop efficient anchoring devices for these FRP sheets is underlined. The behavior of such a novel HAD （hybrid anchoring device） capable of anchoring CFRP （carbon fiber reinforcing plastic） sheets to RC structural elements, is presented and discussed. The behavior of the device itself was studied through a 3D non-linear numerical simulation at the preliminary design stage in order to establish certain desired features such as the ductile behavior of the device itself as well as the satisfactory performance of the FRP sheets wrapped around this device. This HAD was next applied as part of a strengthening scheme aimed to upgrade the flexural capacity of an RC bridge-type pier specimen subjected to a cyclic seismic-type loading sequence. The obtained results demonstrated an increase in the specimen＇s flexural capacity by 100% as well as a similar increase in its capability of dissipating energy in a ductile manner during the cyclic load sequence. Moreover, the employed 3D non-linear numerical simulation yielded reasonably good agreement between the measured and the predicted cyclic response of this specimen strengthened by CFRP layers, which were anchored by the novel HAD. The successful behavior of this novel HAD, which has been patented with No. WO2011073696, is currently being tried with a number of other retrofitting schemes employing FRP sheets externally attached on RC structural elements.展开更多
The performance of a new fiber-reinforced cementitious matrix(FRCM)system developed using custom-designed mortar and fabrics is investigated in this study.The behavior of this system is evaluated in terms of both the ...The performance of a new fiber-reinforced cementitious matrix(FRCM)system developed using custom-designed mortar and fabrics is investigated in this study.The behavior of this system is evaluated in terms of both the flexural and shear strengthening of reinforced concrete beams.Eight beams are designed to assess the effectiveness of the FRCM system in terms of flexural strengthening,and four specimens are designed to investigate their shear behavior.The parameters investigated for flexural strengthening are the number of layers,span/depth ratio,and the strengthening method.Unlike previous studies,custom fabrics with similar axial stiffness are used in all strengthening methods in this study.In the shear-strengthened specimens,the effects of the span/depth ratio and strengthening system type(fiberreinforced polymer(FRP)or FRCM)are investigated.The proposed FRCM system exhibits desirable flexural and shear strengthening for enhancing the load capacity,provides sufficient bonding with the substrate,and prevents premature failure modes.Considering the similar axial stiffness of fabrics used in both FRCM and FRP systems and the higher load capacity of specimens strengthened by the former,cement-based mortar performs better than epoxy.展开更多
文摘Corrosion of steel structures is unavoidable and the structural performance decreases dramatically due to the corrosion. As a repairing method for corroded steel members, bonding carbon fiber sheets with resin had been developed. The purpose of this study is to propose the flexural strengthening method for steel members by using CFRP （carbon fiber reinforced polymer） strand sheets. In order to clarify the stiffening effect and the debonding characteristics of CFRP strand sheets, and to optimize the strengthening design specifications, the flexural tests using high tension steel beams strengthened with CFRP strand sheets are performed. Two cases of experiments are carried out. In Experiment 1, the result from previous research is reflected in the strengthening design. Moreover in Experiment 2, the debonding characteristics obtained from Experiment 1 are reflected. As a result, it was clarified that CFRP strand sheets have stiffening effect equivalent to the theoretical value and its debonding property is practically high enough when FRP （fiber reinforcement polymer） sheets have an appropriate bonding length.
文摘The potential of externally applied FRP （fiber-reinforced plastic） sheets, being employed in retrofitting schemes aimed to repair and strengthen RC （reinforced concrete） structural elements damaged by prototype strong earthquakes, is presented and discussed in this study. The limitation of the debonding mode of failure of these FRP sheets is highlighted and the necessity to develop efficient anchoring devices for these FRP sheets is underlined. The behavior of such a novel HAD （hybrid anchoring device） capable of anchoring CFRP （carbon fiber reinforcing plastic） sheets to RC structural elements, is presented and discussed. The behavior of the device itself was studied through a 3D non-linear numerical simulation at the preliminary design stage in order to establish certain desired features such as the ductile behavior of the device itself as well as the satisfactory performance of the FRP sheets wrapped around this device. This HAD was next applied as part of a strengthening scheme aimed to upgrade the flexural capacity of an RC bridge-type pier specimen subjected to a cyclic seismic-type loading sequence. The obtained results demonstrated an increase in the specimen＇s flexural capacity by 100% as well as a similar increase in its capability of dissipating energy in a ductile manner during the cyclic load sequence. Moreover, the employed 3D non-linear numerical simulation yielded reasonably good agreement between the measured and the predicted cyclic response of this specimen strengthened by CFRP layers, which were anchored by the novel HAD. The successful behavior of this novel HAD, which has been patented with No. WO2011073696, is currently being tried with a number of other retrofitting schemes employing FRP sheets externally attached on RC structural elements.
基金supported by the Ferdowsi University of Mashhad.
文摘The performance of a new fiber-reinforced cementitious matrix(FRCM)system developed using custom-designed mortar and fabrics is investigated in this study.The behavior of this system is evaluated in terms of both the flexural and shear strengthening of reinforced concrete beams.Eight beams are designed to assess the effectiveness of the FRCM system in terms of flexural strengthening,and four specimens are designed to investigate their shear behavior.The parameters investigated for flexural strengthening are the number of layers,span/depth ratio,and the strengthening method.Unlike previous studies,custom fabrics with similar axial stiffness are used in all strengthening methods in this study.In the shear-strengthened specimens,the effects of the span/depth ratio and strengthening system type(fiberreinforced polymer(FRP)or FRCM)are investigated.The proposed FRCM system exhibits desirable flexural and shear strengthening for enhancing the load capacity,provides sufficient bonding with the substrate,and prevents premature failure modes.Considering the similar axial stiffness of fabrics used in both FRCM and FRP systems and the higher load capacity of specimens strengthened by the former,cement-based mortar performs better than epoxy.
